1.2 A, Ultralow Noise, High PSRR, RF Linear Regulator ADP7157 FEATURES APPLICATIONS Regulation to noise sensitive applications: phase-locked loops (PLLs), voltage controlled oscillators (VCOs), and PLLs with integrated VCOs Communications and infrastructure Backhaul and microwave links GENERAL DESCRIPTION The ADP7157 is an adjustable linear regulator that operates from 2.3 V to 5.5 V and provides up to 1.2 A of output current. Output voltages from 1.2 V to 3.3 V are possible depending on the model. Using an advanced proprietary architecture, the device provides high power supply rejection and ultralow noise, achieving excellent line and load transient response with only a 10 F ceramic output capacitor. The ADP7157 is available in four models that optimize power dissipation and PSRR performance as a function of the input and output voltage. See Table 9 and Table 10 for selection guides. The typical output noise the ADP7157 regulator is 0.9 V rms from 100 Hz to 100 kHz and 1.7 nV/Hz for noise spectral density from 10 kHz to 1 MHz. The ADP7157 is available in 10-lead, 3 mm x 3 mm LFCSP and 8-lead SOIC packages, making it not only a very compact solution, but also providing excellent thermal performance for applications requiring up to 1.2 A of output current in a small, low profile footprint. Rev. B TYPICAL APPLICATION CIRCUIT ADP7157 VIN = 3.8V VIN CIN 10F VOUT = 3.3V VOUT COUT 10F VOUT_SENSE ON EN REF CREF 1F OFF CBYP 1F BYP CREG 1F VREG R1 REF_SENSE VOUT = 1.2V x (R1 + R2)/R2 R2 1k < R2 < 200k 12938-001 GND Figure 1. Regulated 3.3 V Output from a 3.8 V Input Table 1. Related Devices Model ADP7159, ADP7158 ADP7156 ADM7150, ADM7151 ADM7154, ADM7155 ADM7160 Input Voltage 2.3 V to 5.5 V 2.3 V to 5.5 V 4.5 V to 16 V 2.3 V to 5.5 V 2.2 V to 5.5 V Output Current 2A Fixed/ Adjustable Fixed 1.2 A Fixed/ Adjustable Fixed/ Adjustable Fixed/ Adjustable Fixed 800 mA 600 mA 200 mA 1k NOISE SPECTRAL DENSITY (nV/Hz) Input voltage range: 2.3 V to 5.5 V Adjustable output voltage range (VOUT): 1.2 V to 3.3 V Maximum load current: 1.2 A Low noise 0.9 V rms typical output noise from 100 Hz to 100 kHz 1.6 V rms typical output noise from 10 Hz to 100 kHz Noise spectral density: 1.7 nV/Hz from 10 kHz to 1 MHz Power supply rejection ratio (PSRR) 82 dB from 1 kHz to 100 kHz 55 dB at 1 MHz Dropout voltage: 120 mV typical at IOUT = 1.2 A, VOUT = 3.3 V Initial accuracy: 0.6% at ILOAD = 10 mA Accuracy over line, load, and temperature: 1.5% Operating supply current (IGND) 4.0 mA typical at 0 A 7.0 mA typical at 1.2 A Low shutdown current: 0.2 A typical Stable with a 10 F ceramic output capacitor 10-lead, 3 mm x 3 mm LFCSP and 8-lead SOIC packages Precision enable Supported by ADIsimPower tool Package 10-lead LFCSP/ 8-lead SOIC 10-lead LFCSP/ 8-lead SOIC 8-lead LFCSP/ 8-lead SOIC 8-lead LFCSP/ 8-lead SOIC 6-lead LFCSP/ 5-lead TSOT CBYP CBYP CBYP CBYP = 1F = 10F = 100F = 1000F 100 10 1 0.1 10 100 1k 10k 100k FREQUENCY (Hz) 1M 10M 12939-002 Data Sheet Figure 2. Noise Spectral Density at Different Values of CBYP, VOUT = 3.3 V Document Feedback Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 (c)2016 Analog Devices, Inc. All rights reserved. Technical Support www.analog.com ADP7157 Data Sheet TABLE OF CONTENTS Features .............................................................................................. 1 ADIsimPower Design Tool ....................................................... 14 Applications ....................................................................................... 1 Capacitor Selection .................................................................... 14 General Description ......................................................................... 1 Undervoltage Lockout (UVLO) ............................................... 15 Typical Application Circuit ............................................................. 1 Programmable Precision Enable .............................................. 16 Revision History ............................................................................... 2 Start-Up Time ............................................................................. 17 Specifications..................................................................................... 3 REF, BYP, and VREG Pins......................................................... 17 Absolute Maximum Ratings ............................................................ 5 Current-Limit and Thermal Shutdown ................................... 17 Thermal Data ................................................................................ 5 Thermal Considerations............................................................ 17 Thermal Resistance ...................................................................... 5 PSRR Performance ..................................................................... 20 ESD Caution .................................................................................. 5 PCB Layout Considerations .......................................................... 21 Pin Configurations and Function Descriptions ........................... 6 Outline Dimensions ....................................................................... 22 Typical Performance Characteristics ............................................. 7 Ordering Guide .......................................................................... 23 Theory of Operation ...................................................................... 13 Applications Information .............................................................. 14 REVISION HISTORY 11/2016--Rev. A to Rev. B Changes to Table 3 ............................................................................ 4 5/2016--Rev. 0 to Rev. A Added Note 2 to Table 2; Renumbered Sequentially ................... 4 Change to Figure 4 ........................................................................... 6 Change to Programmable Precision Enable Section ................. 16 3/2016--Revision 0: Initial Version Rev. B | Page 2 of 23 Data Sheet ADP7157 SPECIFICATIONS VIN = VOUT_MAX 1 + 0.5 V; VEN = VIN; ILOAD = 10 mA; CIN = COUT = 10 F; CREG = CREF = CBYP = 1 F; TA = 25C for typical specifications; TA = -40C to +125C for minimum/maximum specifications, unless otherwise noted. Table 2. Parameter INPUT VOLTAGE RANGE LOAD CURRENT OPERATING SUPPLY CURRENT Symbol VIN ILOAD IGND SHUTDOWN CURRENT NOISE 2 Output Noise IIN-SD Noise Spectral Density POWER SUPPLY REJECTION RATIO2 ADP7157-01 OUTNSD PSRR OUTNOISE ADP7157-02 ADP7157-03 ADP7157-04 OUTPUT VOLTAGE ACCURACY Output Voltage 3 Initial Accuracy REGULATION Line Load 4 CURRENT-LIMIT THRESHOLD 5 REF VOUT DROPOUT VOLTAGE 6 PULL-DOWN RESISTANCE VOUT VREG REF BYP START-UP TIME2, 7 VOUT VREG REF THERMAL SHUTDOWN2 Threshold Hysteresis VOUT VOUT VOUT/VIN VOUT/IOUT ILIMIT Test Conditions/Comments Min 2.3 ILOAD = 0 A ILOAD = 1.2 A EN = ground VOUT = 1.2 V to 3.3 V 10 Hz to 100 kHz 100 Hz to 100 kHz 10 kHz to 1 MHz ILOAD = 1.2 A 1 kHz to 100 kHz, VIN = 2.3 V, VOUT = 1.8 V 1 MHz, VIN = 2.3 V, VOUT = 1.8 V 1 kHz to 100 kHz, VIN = 2.8 V, VOUT = 2.3 V 1 MHz, VIN = 2.8 V, VOUT = 2.3 V 1 kHz to 100 kHz, VIN = 3.4 V, VOUT = 2.9 V 1 MHz, VIN = 3.4 V, VOUT = 2.9 V 1 kHz to 100 kHz, VIN = 3.8 V, VOUT = 3.3 V 1 MHz, VIN = 3.8 V, VOUT = 3.3 V ILOAD = 10 mA, TA = 25C 10 mA < ILOAD < 1.2 A, TA = 25C 10 mA < ILOAD < 1.2 A, TA = -40C to +125C VIN = VOUT_MAX + 0.5 V to 5.5 V IOUT = 10 mA to 1.2 A 4.0 7.0 0.2 VOUT-PULL VREG-PULL VREF-PULL VBYP-PULL IOUT = 600 mA, VOUT = 3.3 V IOUT = 1.2 A, VOUT = 3.3 V EN = 0 V, VIN = 5.5 V VOUT = 1 V VREG = 1 V VREF = 1 V VBYP = 1 V VOUT = 3.3 V tSTART-UP tREG-START-UP tREF-START-UP TSSD TSSD-HYS TJ rising Rev. B | Page 3 of 23 Max 5.5 1.2 8.0 12.0 4 Unit V A mA mA A 1.6 0.9 1.7 V rms V rms nV/Hz 70 52 72 53 75 55 82 55 dB dB dB dB dB dB dB dB 1.2 -0.6 -1.0 -1.5 3.3 +0.6 +1.0 +1.5 V % % % -0.1 +0.1 0.3 %/V %/A 2.4 80 170 mA A mV mV 1.4 VDROPOUT Typ 22 1.8 60 120 650 31 850 650 k 1.2 0.6 0.5 ms ms ms 150 15 C C ADP7157 Parameter UNDERVOLTAGE THRESHOLDS Input Voltage Rising Falling Hysteresis VREG THRESHOLDS 8 Rising Falling Hysteresis EN INPUT PRECISION EN Input Logic High Logic Low Logic Hysteresis LEAKAGE CURRENT REF_SENSE EN Data Sheet Symbol Test Conditions/Comments Min Typ Max Unit UVLORISE UVLOFALL UVLOHYS 2.22 2.02 200 2.29 1.95 V V mV VREGUVLORISE VREGUVLOFALL VREGUVLOHYS 1.94 1.60 V V mV 1.31 1.22 V V mV 185 2.3 V VIN 5.5 V ENHIGH ENLOW ENHYS IREF_SENSE_LKG IEN_LKG 1.13 1.05 1.22 1.13 90 10 0.01 EN = VIN or ground 1 nA A VOUT_MAX is the maximum output voltage of each version of the ADP7157. Guaranteed by characterization, but not production tested. This output voltage specification is for ADP7157-04 version. Table 10 provides a guide for selecting one of the four versions of the ADP7157 based on voltage range. 4 This specification is based on an endpoint calculation using 10 mA and 1.2 A loads. 5 Current-limit threshold is the current at which the output voltage drops to 90% of the specified typical value. For example, the current limit for a 3.0 V output voltage is the current that causes the output voltage to drop to 90% of 3.0 V or 2.7 V. 6 Dropout voltage is the input to output voltage differential when the input voltage is set to the nominal output voltage. Dropout applies only for output voltages above 2.3 V. 7 Start-up time is the time from the rising edge of VEN to VOUT, VREG, or VREF being at 90% of its nominal value. 8 The output voltage is disabled until the VREG UVLO rise threshold is crossed. The VREG output is disabled until the input voltage UVLO rising threshold is crossed. 1 2 3 Table 3. Input and Output Capacitors, Recommended Specifications Parameter MINIMUM CAPACITANCE Input 1 Regulator1 Output1 Bypass Reference CAPACITOR EFFECTIVE SERIES RESISTANCE (ESR) COUT, CIN CREG, CREF CBYP 1 Symbol CIN CREG COUT CBYP CREF RESR Test Conditions/Comments TA = -40C to +125C Min Typ 7.0 0.7 7.0 0.1 0.7 10.0 1.0 10.0 1.0 1.0 Max Unit F F F F F TA = -40C to +125C 0.1 0.2 2.0 The minimum input, regulator, and output capacitances must be greater than 7.0 F over the full range of operating conditions. The full range of operating conditions in the application must be considered during device selection to ensure that the minimum capacitance specification is met. X7R and X5R type capacitors are recommended, and Y5V and Z5U capacitors are not recommended for use with any LDO. Rev. B | Page 4 of 23 Data Sheet ADP7157 ABSOLUTE MAXIMUM RATINGS Table 4. Parameter VIN to Ground VREG to Ground VOUT to Ground VOUT_SENSE to Ground VOUT to VOUT_SENSE BYP to VOUT EN to Ground BYP to Ground REF to Ground REF_SENSE to Ground Storage Temperature Range Operational Junction Temperature Range Soldering Conditions Rating -0.3 V to +7 V -0.3 V to VIN or +4 V (whichever is less) -0.3 V to VREG or +4 V (whichever is less) -0.3 V to VREG or +4 V (whichever is less) 0.3 V 0.3 V -0.3 V to +7 V -0.3 V to VREG or +4 V (whichever is less) -0.3 V to VREG or +4 V (whichever is less) -0.3 V to +4 V -65C to +150C -40C to +125C JEDEC J-STD-020 Stresses at or above those listed under Absolute Maximum Ratings may cause permanent damage to the product. This is a stress rating only; functional operation of the product at these or any other conditions above those indicated in the operational section of this specification is not implied. Operation beyond the maximum operating conditions for extended periods may affect product reliability. THERMAL DATA Absolute maximum ratings apply individually only, not in combination. The ADP7157 can be damaged when the junction temperature limits are exceeded. Monitoring ambient temperature does not guarantee that TJ is within the specified temperature limits. In applications with high power dissipation and poor thermal resistance, the maximum ambient temperature may need to be derated. In applications with moderate power dissipation and low printed circuit board (PCB) thermal resistance, the maximum ambient temperature can exceed the maximum limit as long as the junction temperature is within specification limits. The junction temperature (TJ) of the device is dependent on the ambient temperature (TA), the power dissipation of the device (PD), and the junction to ambient thermal resistance of the package (JA). The maximum TJ is calculated from the TA and the PD using the following formula: TJ = TA + (PD x JA) The junction to ambient thermal resistance (JA) of the package is based on modeling and calculation using a 4-layer board. The junction to ambient thermal resistance is highly dependent on the application and board layout. In applications where high maximum power dissipation exists, close attention to thermal board design is required. The JA value may vary, depending on PCB material, layout, and environmental conditions. The specified JA values are based on a 4-layer, 4 in. x 3 in. circuit board. See the JESD51-7 standard and the JESD51-9 standard for detailed information on the board construction. JB is the junction to board thermal characterization parameter with units of C/W. JB of the package is based on modeling and calculation using a 4-layer board. JESD51-12, Guidelines for Reporting and Using Electronic Package Thermal Information, states that thermal characterization parameters are not the same as thermal resistances. JB measures the component power flowing through multiple thermal paths rather than a single path as in thermal resistance, JB. Therefore, JB thermal paths include convection from the top of the package as well as radiation from the package, factors that make JB more useful in real-world applications. Use the board temperature (TB) and power dissipation (PD) to calculate the maximum junction temperature (TJ) by TJ = TB + (PD x JB) See the JESD51-8 standard and the JESD51-12 standard for more detailed information about JB. THERMAL RESISTANCE JA, JC, and JB are specified for the worst case conditions, that is, a device soldered in a circuit board for surface-mount packages. Table 5. Thermal Resistance Package Type 10-Lead LFCSP 8-Lead SOIC ESD CAUTION Rev. B | Page 5 of 23 JA 53.8 50.4 JC 15.6 42.3 JB 29.1 30.1 Unit C/W C/W ADP7157 Data Sheet PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS VOUT 1 10 VIN VOUT 1 VOUT 2 9 VIN VOUT_SENSE 2 TOP VIEW (Not to Scale) BYP 4 EN 5 BYP 3 8 VREG EN 4 VIN VREG TOP VIEW 6 REF (Not to Scale) 5 REF_SENSE 7 7 REF NOTES 1. THE EXPOSED PAD IS LOCATED ON THE BOTTOM OF THE PACKAGE. THE EXPOSED PAD ENHANCES THERMAL PERFORMANCE, AND IT IS ELECTRICALLY CONNECTED TO GROUND INSIDE THE PACKAGE. CONNECT THE EP TO THE GROUND PLANE ON THE BOARD TO ENSURE PROPER OPERATION. NOTES 1. THE EXPOSED PAD IS LOCATED ON THE BOTTOM OF THE PACKAGE. THE EXPOSED PAD ENHANCES THERMAL PERFORMANCE, AND IT IS ELECTRICALLY CONNECTED TO GROUND INSIDE THE PACKAGE. CONNECT THE EP TO THE GROUND PLANE ON THE BOARD TO ENSURE PROPER OPERATION. 12938-003 6 REF_SENSE Figure 3. 10-Lead LFCSP Pin Configuration 12938-004 ADP7157 VOUT_SENSE 3 8 ADP7157 Figure 4. 8-Lead SOIC Pin Configuration Table 6. Pin Function Descriptions LFCSP 1, 2 3 Pin No. SOIC 1 2 Mnemonic VOUT VOUT_SENSE 4 3 BYP 5 4 EN 6 5 REF_SENSE 7 6 REF 8 7 VREG 9, 10 8 VIN EP Description Regulated Output Voltage. Bypass VOUT to ground with a 10 F or greater capacitor. Output Sense. VOUT_SENSE is internally connected to VOUT with a 10 resistor. Connect VOUT_SENSE as close to the load as possible. Low Noise Bypass Capacitor. Connect a 1 F or greater capacitor from the BYP pin to ground to reduce noise. Do not connect a load to this pin. Enable. Drive EN high to turn on the regulator, and drive EN low to turn off the regulator. For automatic startup, connect EN to VIN. Reference Sense. This pin sets the output voltage with an external resistor divider. VOUT = VREF x (R1 + R2)/R2, where VREF = 1.2 V. Connect REF_SENSE to the REF pin. Do not connect REF_SENSE to VOUT or ground. Low Noise Reference Voltage Output. Bypass REF to ground with a 1 F or greater capacitor. Short REF_SENSE to REF for fixed output voltages. Do not connect a load to this pin. Regulated Input Supply Voltage to the LDO Amplifier. Bypass VREG to ground with a 1 F or greater capacitor. Regulator Input Supply Voltage. Bypass VIN to ground with a 10 F or greater capacitor. Exposed Pad. The exposed pad is located on the bottom of the package. The exposed pad enhances thermal performance, and it is electrically connected to ground inside the package. Connect the exposed pad to the ground plane on the board to ensure proper operation. Rev. B | Page 6 of 23 Data Sheet ADP7157 TYPICAL PERFORMANCE CHARACTERISTICS 1.0 3.35 0.9 3.34 0.8 3.33 0.7 3.32 0.6 VOUT (V) 5.5V 5.0V 4.0V 3.0V 0.5 0.4 = 0mA = 10mA = 100mA = 600mA = 1200mA 3.31 3.30 3.29 0.3 3.28 0.2 3.27 0.1 3.26 2.5V -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) 3.25 3.8 12938-005 2.3V 0 -40 3.35 3.34 3.33 ILOAD ILOAD ILOAD ILOAD ILOAD 4.0 4.2 4.4 4.6 4.8 5.0 5.2 5.4 5.6 VIN (V) Figure 5. Shutdown Current (IIN-SD) vs. Temperature at Various Input Voltages (VIN), VOUT =1.8 V Figure 8. Output Voltage (VOUT) vs. Input Voltage (VIN) at Various Loads, VOUT = 3.3 V 14 = 0mA = 10mA = 100mA = 600mA = 1200mA 13 12 11 ILOAD ILOAD ILOAD ILOAD ILOAD = 0mA = 10mA = 100mA = 600mA = 1200mA 10 3.32 9 3.31 IGND (mA) VOUT (V) ILOAD ILOAD ILOAD ILOAD ILOAD 12938-008 IIN-SD (A) VIN = VOUT + 0.5 V or 2.3 V, whichever is greater; VEN = VIN; VOUT = 3.3 V; ILOAD = 10 mA; CIN = COUT = 10 F; CREG = CREF = CBYP = 1 F; TA = 25C, unless otherwise noted. 3.30 3.29 8 7 6 5 3.28 4 3 3.27 2 3.26 0 20 40 60 80 100 120 140 TEMPERATURE (C) 0 -40 12938-006 -20 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 6. Output Voltage (VOUT) vs. Temperature at Various Loads, VOUT = 3.3 V 12938-009 1 3.25 -40 Figure 9. Ground Current (IGND) vs. Temperature at Various Loads, VOUT = 3.3 V 3.35 14 3.34 13 12 3.33 11 10 9 3.31 IGND (mA) VOUT (V) 3.32 3.30 3.29 8 7 6 5 3.28 4 3 3.27 2 3.26 10m 100m 1 10 ILOAD (A) 0 0.1m 12938-007 1m 1m 10m 100m ILOAD (A) Figure 7. Output Voltage (VOUT) vs. Load Current (ILOAD), VOUT = 3.3 V 1 10 12938-010 1 3.25 0.1m Figure 10. Ground Current (IGND) vs. Load Current (ILOAD), VOUT = 3.3 V Rev. B | Page 7 of 23 ADP7157 Data Sheet 14 14 ILOAD = 0mA ILOAD = 10mA ILOAD = 100mA ILOAD = 600mA ILOAD = 1200mA 12 12 11 10 9 9 IGND (mA) 10 8 7 6 8 7 6 5 5 4 4 3 3 2 2 1 1 0 3.8 4.0 4.2 4.6 4.4 4.8 5.0 5.2 5.4 5.6 VIN (V) 0 3.1 12938-011 IGND (mA) 11 13 ILOAD = 0mA ILOAD = 10mA ILOAD = 100mA ILOAD = 600mA ILOAD = 1200mA 3.2 3.3 3.4 3.5 3.6 3.7 3.8 VIN (V) Figure 11. Ground Current (IGND) vs. Input Voltage (VIN) at Various Loads, VOUT = 3.3 V 12938-014 13 Figure 14. Ground Current (IGND) vs. Input Voltage (VIN) in Dropout, VOUT = 3.3 V 1.25 0.16 1.24 0.14 1.23 0.12 ILOAD ILOAD ILOAD ILOAD ILOAD = 0mA = 10mA = 100mA = 600mA = 1200mA VOUT (V) VDROPOUT (V) 1.22 0.10 0.08 1.21 1.20 1.19 0.06 1.18 0.04 1.17 0.02 100m 1 10 ILOAD (A) 1.15 -40 12938-012 0 10m 20 40 60 80 100 120 140 Figure 15. Output Voltage (VOUT) vs. Temperature at Various Loads, VOUT = 1.2 V 3.40 3.30 0 TEMPERATURE (C) Figure 12. Dropout Voltage (VDROPOUT) vs. Load Current (ILOAD), VOUT = 3.3 V 3.35 -20 12938-015 1.16 1.25 ILOAD ILOAD ILOAD ILOAD ILOAD = 0mA = 10mA = 100mA = 600mA = 1200mA 1.24 1.23 1.22 VOUT (V) VOUT (V) 3.25 3.20 1.21 1.20 1.19 3.15 1.18 3.10 1.17 3.05 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 VIN (V) Figure 13. Output Voltage (VOUT) vs. Input Voltage (VIN) in Dropout, VOUT = 3.3 V 1.15 0.1m 1m 10m 100m ILOAD (A) 1 10 12938-016 1.16 12938-013 3.00 3.0 Figure 16. Output Voltage (VOUT) vs. Load Current (ILOAD), VOUT = 1.2 V Rev. B | Page 8 of 23 Data Sheet ADP7157 1.25 14 ILOAD = 0mA ILOAD = 10mA ILOAD = 100mA ILOAD = 600mA ILOAD = 1200mA 1.24 1.23 13 12 11 10 1.22 ILOAD = 1200mA IGND (mA) 1.20 1.19 8 ILOAD = 600mA 7 6 ILOAD = 100mA 5 1.18 4 1.17 3 ILOAD = 10mA ILOAD = 0mA 2 1.16 1 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 VIN (V) 0 2.3 12938-017 1.15 2.3 2.6 2.9 3.2 3.5 3.8 4.1 4.4 4.7 5 5.3 5.6 VIN (V) Figure 17. Output Voltage (VOUT) vs. Input Voltage (VIN) at Various Loads, VOUT = 1.2 V 12938-020 VOUT (V) 9 1.21 Figure 20. Ground Current (IGND) vs. Input Voltage (VIN) at Various Loads, VOUT = 1.2 V 0 14 13 ILOAD ILOAD ILOAD ILOAD -10 12 11 -20 10 -30 = 10mA = 100mA = 600mA = 1200mA 7 6 5 ILOAD = 1200mA ILOAD = 600mA -40 -50 -60 ILOAD = 100mA -70 4 3 2 ILOAD = 10mA ILOAD = 0mA -80 -90 1 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) -100 12938-018 0 -40 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) Figure 18. Ground Current (IGND) vs. Temperature at Various Loads, VOUT = 1.2 V 12938-021 8 PSRR (dB) IGND (mA) 9 Figure 21. Power Supply Rejection Ratio (PSRR) vs. Frequency at Various Loads, VOUT = 3.3 V 14 0 13 900mV 800mV 700mV 600mV 500mV -10 12 11 -20 10 -30 PSRR (dB) IGND (mA) 9 8 7 6 -40 -50 -60 5 4 -70 3 -80 2 1m 10m 100m ILOAD (A) 1 10 12938-019 0 0.1m -100 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) Figure 22. Power Supply Rejection Ratio (PSRR) vs. Frequency at Various Headroom Voltages, VOUT = 3.3 V, 1.2 A Load Figure 19. Ground Current (IGND) vs. Load Current (ILOAD), VOUT = 1.2 V Rev. B | Page 9 of 23 12938-022 -90 1 ADP7157 0 0 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz 10MHz -10 -20 -30 -20 -30 -40 -50 -60 -70 -50 -60 -80 -90 -90 0.7 0.9 0.8 Figure 23. Power Supply Rejection Ratio (PSRR) vs. Headroom Voltage at Various Frequencies, VOUT = 3.3 V, 1.2 A Load 0 ILOAD ILOAD ILOAD ILOAD -10 -20 -100 1.0 12938-023 0.6 1.3 1.2 1.1 1.4 HEADROOM (V) 12938-026 -80 HEADROOM (V) Figure 26. Power Supply Rejection Ratio (PSRR) vs. Headroom Voltage at Various Frequencies, VOUT = 1.2 V, 1.2 A Load 0 = 10mA = 100mA = 600mA = 1200mA 1F 10F 100F 1000F -10 -20 -30 -30 -50 -60 -40 -50 -60 -70 -70 -80 -80 -90 -100 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) 12938-024 -90 -100 1k 100k 10k 1M 10M 2.5 2.0 OUTPUT NOISE (V rms) -20 100 Figure 27. Power Supply Rejection Ratio (PSRR) vs. Frequency at Different CBYP Values, VOUT = 3.3 V, VIN = 4.0 V, 1.2 A Load 1.4V 1.3V 1.2V 1.1V 1.0V -10 10 FREQUENCY (Hz) Figure 24. Power Supply Rejection Ratio (PSRR) vs. Frequency at Various Loads, VOUT = 1.2 V 0 1 12938-027 -40 PSRR (dB) PSRR (dB) -40 -70 -100 0.5 -30 PSRR (dB) 10Hz 100Hz 1kHz 10kHz 100kHz 1MHz 10MHz -10 PSRR (dB) PSRR (dB) Data Sheet -40 -50 -60 -70 -80 10Hz TO 100kHz 1.5 1.0 100Hz TO 100kHz 0.5 1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) Figure 25. Power Supply Rejection Ratio (PSRR) vs. Frequency at Various Headroom Voltages, VOUT = 1.2 V, 1.2 A Load 0 10m 100m 1 LOAD CURRENT (A) Figure 28. RMS Output Noise vs. Load Current (ILOAD) Rev. B | Page 10 of 23 10 12938-028 -100 12938-025 -90 Data Sheet ADP7157 2.5 10Hz TO 100kHz 1.5 1.0 100Hz TO 100kHz 0.5 3.0 2.5 2.0 1.5 3.5 OUTPUT VOLTAGE (V) 100 10 1 0.1 10 12938-029 0 1.0 10k 100k 1M 10M = 1F = 10F = 100F = 1000F SLEW RATE = 2.5A/s 100 1 IOUT 10 2 VOUT 100 1k 100k 10k 10M 1M FREQUENCY (Hz) CH1 500mA BW CH2 5.00mV Figure 30. Noise Spectral Density vs. Frequency at Various Values of CBYP 100k ILOAD ILOAD ILOAD ILOAD 10k B W M4.00s A CH1 T 21.10% 700mA 12938-035 1 0.1 10 Figure 33. Load Transient Response, ILOAD = 100 mA to 1.2 A, VOUT = 3.3 V, VIN = 4.0 V, Channel 1 = IOUT, Channel 2 = VOUT = 10mA = 100mA = 600mA = 1200mA SLEW RATE = 1.5A/s IOUT 1k 1 100 VOUT 10 2 1 0.1 0.1 1 10 100 1k 10k 100k FREQUENCY (Hz) Figure 31. Output Noise Spectral Density vs. Frequency at Various Loads, 0.1 Hz to 1 MHz 1M 12938-033 NOISE SPECTRAL DENSITY (nV/Hz) 1k Figure 32. Output Noise Spectral Density vs. Frequency at Various Loads, 10 Hz to 10 MHz 12938-032 NOISE SPECTRAL DENSITY (nV/Hz) CBYP CBYP CBYP CBYP 100 FREQUENCY (Hz) Figure 29. RMS Output Noise vs. Output Voltage 1k = 10mA = 100mA = 600mA = 1200mA CH1 500mA B W CH2 5.00mV B W M4.00s A CH1 T 22.60% 690mA 12938-036 OUTPUT NOISE (V rms) 2.0 ILOAD ILOAD ILOAD ILOAD 12938-034 NOISE SPECTRAL DENSITY (nV/Hz) 1k Figure 34. Load Transient Response, ILOAD = 100 mA to 1.2 A, VOUT = 3.3 V, VIN = 4.0 V, COUT = 22 F, Channel 1 = IOUT, Channel 2 = VOUT Rev. B | Page 11 of 23 ADP7157 Data Sheet SLEW RATE = 2.5A/s SLEW RATE = 1V/s VIN 1 1 VOUT 2 B W CH2 5.00mV B W M4.00s A CH1 T 21.30% 740mA CH1 1.00V B W B W CH2 2.00mV M10.0s A CH1 T 21.80% 12938-040 CH1 500mA 12938-037 2 3.00V Figure 38. Line Transient Response, 1 V Input Step, ILOAD = 1.2 A, VOUT = 1.8 V, VIN = 2.5 V, Channel 1 = VIN, Channel 2 = VOUT Figure 35. Load Transient Response, ILOAD = 100 mA to 1.2 A, VOUT = 1.8 V, VIN = 2.5 V, Channel 1 = IOUT, Channel 2 = VOUT 3.5 SLEW RATE = 2.4A/s 3.0 EN 3.3V 2.5V 1.8V 2.5 IOUT VOUT (V) 1 2 2.0 1.5 VOUT 1.0 B W CH2 5.00mV B W M4.00s A CH1 T 20.70% 740mA 0 -2 -1 0 1 2 3 4 5 6 7 8 TIME (ms) Figure 36. Load Transient Response, ILOAD = 100 mA to 1.2 A, VOUT = 1.8 V, VIN = 2.5 V, COUT = 22 F, Channel 1 = IOUT, Channel 2 = VOUT 12938-041 CH1 500mA 12938-038 0.5 Figure 39. VOUT Start-Up Time After VEN Rising at Various Output Voltages, VIN = 5.0 V, CBYP = 1 F 3.5 SLEW RATE = 1V/s 3.0 VIN VOUT (V) 2.5 VOUT 2 2.0 1.5 1.0 EN 1F 4.7F 10F CH1 1.00V B W CH2 5.00mV B W M10.0s A CH1 T 21.10% 4.34V 12938-039 0.5 0 -2 0 2 4 6 8 10 12 14 16 18 20 TIME (ms) Figure 37. Line Transient Response, 1 V Input Step, ILOAD = 1.2 A, VOUT = 3.3 V, VIN = 3.8 V, Channel 1 = VIN, Channel 2 = VOUT Figure 40. VOUT Start-Up Time Behavior at Various Values of CBYP, VOUT = 3.3 V Rev. B | Page 12 of 23 12938-042 1 Data Sheet ADP7157 THEORY OF OPERATION VIN = 3.8V CIN 10F INTERNAL REGULATOR CURRENT-LIMIT, THERMAL PROTECT COUT 10F VOUT_SENSE REF EN CREF 1F OFF VOUT VOUT_SENSE CBYP 1F BYP CREG 1F VREG REF_SENSE R1 VOUT = 1.2V x (R1 + R2)/R2 R2 1k < R2 < 200k GND GND Figure 42. Typical Adjustable Output Voltage Application Schematic REFERENCE OTA REF_SENSE SHUTDOWN REF EN Figure 41. Simplified Internal Block Diagram Internally, the ADP7157 consists of a reference, an error amplifier, and a P-channel MOSFET pass transistor. The output current is delivered via the PMOS pass device, which is controlled by the error amplifier. The error amplifier compares the reference voltage with the feedback voltage from the output and amplifies the difference. If the feedback voltage is lower than the reference voltage, the gate of the PMOS device pulls lower, allowing more current to pass and increasing the output voltage. If the feedback voltage is higher than the reference voltage, the gate of the PMOS device pulls higher, allowing less current to pass and decreasing the output voltage. By heavily filtering the reference voltage, the ADP7157 achieves 1.7 nV/Hz output typical from 10 kHz to 1 MHz. Because the error amplifier is always in unity gain, the output noise is independent of the output voltage. The ADP7157 output voltage can be adjusted between 1.2 V and 3.3 V and is available in four models that optimize the input voltage and output voltage ranges to keep power dissipation as low as possible without compromising PSRR performance. The output voltage is determined by an external voltage divider according to the following equation: VOUT = 1.2 V x (1 + R1/R2) The R2 value must be greater than 1 k to prevent excessive loading of the reference voltage appearing on the REF pin. To minimize errors in the output voltage caused by the REF_ SENSE pin input current, the R2 value must be less than 200 k. For example, when R1 and R2 each equal 100 k, the output voltage is 2.4 V. The output voltage error introduced by the REF_SENSE pin input current is 10 mV or 0.33%, assuming a maximum REF_SENSE pin input current of 100 nA at TA = 125C. The ADP7157 uses the EN pin to enable and disable the VOUT pin under normal operating conditions. When EN is high, VOUT turns on, and when EN is low, VOUT turns off. For automatic startup, tie EN to VIN. VIN 7V VREG 4V REF REF_SENSE 4V BYP 4V VOUT 4V VOUT_SENSE EN GND 7V 4V 4V 4V 4V 4V 4V 7V 12938-045 BYP 12938-043 VREG VOUT = 3.3V VOUT ON Optimized for use with 10 F ceramic capacitors, the ADP7157 provides excellent transient performance. VIN ADP7157 VIN 12938-044 The ADP7157 is an ultralow noise, high PSRR linear regulator targeting radio frequency (RF) applications. The input voltage range is 2.3 V to 5.5 V, and the device delivers up to a 1.2 A load current. The typical shut-down current consumption is 0.2 A at room temperature. Figure 43. Simplified ESD Protection Block Diagram The ESD protection devices are shown in the block diagram as Zener diodes (see Figure 43). Rev. B | Page 13 of 23 ADP7157 Data Sheet APPLICATIONS INFORMATION ADIsimPOWER DESIGN TOOL Input and VREG Capacitor The ADP7157 is supported by the ADIsimPowerTM design tool set. ADIsimPower is a collection of tools that produces complete power designs optimized for a specific design goal. The tools enable the user to generate a full schematic, bill of materials, and calculate performance within minutes. ADIsimPower can optimize designs for cost, area, efficiency, and device count, taking into consideration the operating conditions and limitations of the IC and all real external components. For more information about, and to obtain ADIsimPower design tools, visit www.analog.com/ADIsimPower. Connecting a 10 F or greater capacitor from VIN to ground reduces the circuit sensitivity to PCB layout, especially when long input traces or high source impedance are encountered. CAPACITOR SELECTION BYP Capacitor Multilayer ceramic capacitors (MLCCs) combine small size, low ESR, low effective series inductance (ESL), and wide operating temperature range, making them an ideal choice for bypass capacitors. They are not without faults, however. Depending on the dielectric material, the capacit-ance can vary dramatically with temperature, dc bias, and ac signal level. Therefore, selecting the proper capacitor results in the best circuit performance. The BYP capacitor, CBYP, is necessary to filter the reference buffer. A 1 F capacitor is typically connected between BYP and ground. Capacitors as small as 0.1 F can be used; however, the output noise voltage of the LDO increases as a result. The ADP7157 is designed for operation with ceramic capacitors but functions with most commonly used capacitors when care is taken with regard to the ESR value. The ESR of the output capacitor affects the stability of the LDO control loop. A minimum of 10 F capacitance with an ESR of 0.2 or less is recommended to ensure the stability of the ADP7157. Output capacitance also affects transient response to changes in load current. Using a larger value of output capacitance improves the transient response of the ADP7157 to large changes in load current. Figure 44 shows the transient responses for an output capacitance value of 10 F. SLEW RATE = 2.5A/s REF Capacitor The REF capacitor, CREF, is necessary to stabilize the reference amplifier. Connect a 1 F or greater capacitor between REF and ground In addition, the BYP capacitor value can be increased to reduce the noise below 1 kHz at the expense of increasing the start-up time of the LDO. Very large values of CBYP significantly reduce the noise below 10 Hz. Tantalum capacitors are recommended for capacitors larger than approximately 33 F because solid tantalum capacitors are less prone to microphonic noise issues. A 1 F ceramic capacitor in parallel with the larger tantalum capacitor is recommended to ensure good noise performance at higher frequencies. 2.0 1.8 1.6 OUTPUT NOISE (V rms) Output Capacitor To maintain the best possible stability and PSRR performance, connect a 1 F or greater capacitor from VREG to ground. 10Hz TO 100kHz 1.4 1.2 1.0 100Hz TO 100kHz 0.8 0.6 0.4 IOUT 0 1 100 10 1000 CBYP (F) VOUT B W CH2 5.00mV B W M4.00s A CH1 T 21.10% 700mA 12938-046 CH1 500mA Figure 45. RMS Output Noise vs. Bypass Capacitance (CBYP) Figure 44. Output Transient Response, VOUT = 3.3 V, COUT = 10 F, Channel 1 = Load Current, Channel 2 = VOUT Rev. B | Page 14 of 23 12938-047 0.2 Data Sheet ADP7157 CBYP CBYP CBYP CBYP Use Equation 1 to determine the worst case capacitance accounting for capacitor variation over temperature, component tolerance, and voltage. = 1F = 10F = 100F = 1000F 100 CEFF = CBIAS x (1 - Tempco x (1 - TOL) 1 0.1 10 100 1k 10k 100k 1M 10M FREQUENCY (Hz) Figure 46. Noise Spectral Density vs. Frequency at Various CBYP Values Capacitor Properties Any good quality ceramic capacitors can be used with the ADP7157 if they meet the minimum capacitance and maximum ESR requirements. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior over temperature and applied voltage. Capacitors must have a dielectric adequate to ensure the minimum capacitance over the necessary temperature range and dc bias conditions. X5R or X7R dielectrics with a voltage rating of 6.3 V to 50 V are recommended. However, Y5V and Z5U dielectrics are not recommended because of their poor temperature and dc bias characteristics. Figure 47 depicts the capacitance vs. dc bias voltage of a 1206, 10 F, 10 V, X5R capacitor. The voltage stability of a capacitor is strongly influenced by the capacitor size and voltage rating. In general, a capacitor in a larger package or higher voltage rating exhibits better stability. The temperature variation of the X5R dielectric is ~15% over the -40C to +85C temperature range and is not a function of package or voltage rating. In this example, the worst case temperature coefficient (TEMPCO) over -40C to +85C is assumed to be 15% for an X5R dielectric. The tolerance of the capacitor (TOL) is assumed to be 10%, and CBIAS is 9.72 F at 5 V, as shown in Figure 47. Substituting these values in Equation 1 yields CEFF = 9.72 F x (1 - 0.15) x (1 - 0.1) = 7.44 F Therefore, the capacitor chosen in this example meets the minimum capacitance requirement of the LDO over temperature and tolerance at the chosen output voltage. To guarantee the performance of the ADP7157, it is imperative that the effects of dc bias, temperature, and tolerances on the behavior of the capacitors be evaluated for each application. UNDERVOLTAGE LOCKOUT (UVLO) The ADP7157 also incorporates an internal UVLO circuit to disable the output voltage when the input voltage is less than the minimum input voltage rating of the regulator. The upper and lower thresholds are internally fixed with about 200 mV of hysteresis. 2.5 10 +125C +25C -40C 2.0 VOUT (V) 12 1.5 1.0 8 0.5 0 1.9 4 2.0 2.1 VIN (V) 2.2 2.3 12938-050 6 Figure 48. Typical UVLO Behavior at Various Temperatures, VOUT = 3.3 V 2 0 0 2 4 6 8 DC BIAS VOLTAGE (V) Figure 47. Capacitance vs. DC Bias Voltage 10 12938-049 CAPACITANCE (F) (1) where: CBIAS is the effective capacitance at the operating voltage. Tempco is the worst case capacitor temperature coefficient. TOL is the worst case component tolerance. 10 12938-048 NOISE SPECTRAL DENSITY (nV/Hz) 1k Figure 48 shows the typical hysteresis of the UVLO function. This hysteresis prevents on/off oscillations that can occur when caused by noise on the input voltage as it passes through the threshold points. Rev. B | Page 15 of 23 ADP7157 Data Sheet 1.250 The ADP7157 includes the discharge resistor on each VOUT, VREG, VREF, and BYP pin. These resistors are turned on when the device is disabled, helping to quickly discharge the associated capacitor. 1.175 1.150 FALLING 1.100 2.5 -40C -5C +25C +85C +125C 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) Figure 51. Typical EN Threshold vs. Input Voltages (VIN) for Different Temperatures 2.5 VOUT (V) 1.200 1.125 3.5 3.0 RISING 1.225 12938-053 The ADP7157 uses the EN pin to enable and disable the VOUT pin under normal operating conditions. As shown in Figure 49, when a rising voltage on EN crosses the upper threshold, nominally 1.22 V, VOUT turns on. When a falling voltage on EN crosses the lower threshold, nominally 1.13 V, VOUT turns off. The hysteresis of the EN threshold is approximately 90 mV. EN PRECISION THRESHOLD (V) PROGRAMMABLE PRECISION ENABLE The upper and lower thresholds are user programmable and can be set higher than the nominal 1.22 V threshold by using two resistors. The resistance values, REN1 and REN2, can be determined from 2.0 1.5 REN1 = REN2 x (VEN - 1.22 V)/1.22 V 1.0 where: REN2 typically ranges from 10 k to 100 k. VEN is the desired turn-on voltage. 0 1.00 1.05 1.10 1.15 1.20 1.25 1.30 EN PIN VOLTAGE (V) 12938-051 0.5 Figure 49. Typical VOUT Response to EN Pin Operation The hysteresis voltage increases by the factor (REN1 + REN2)/REN2 For the example shown in Figure 52, the EN threshold is 2.44 V with a hysteresis of 200 mV. 3.5 EN VOUT 3.0 ADP7157 2.0 OFF 1.5 VOUT CREG 1F COUT 10F REF EN R1 BYP REF_SENSE 1.0 0.5 VOUT = 3.3V VOUT_SENSE REN2 100k CBYP 1F CREF 1F VOUT = 1.2V x (R1 + R2)/R2 R2 1k < R2 < 200k VREG GND 0 -2 -1 0 1 2 3 4 5 6 7 TIME (ms) Figure 50. Typical VOUT Response to EN Pin Operation (VEN), VOUT = 3.3 V, VIN = 5 V, CBYP = 1 F 8 12938-052 VOUT (V) ON REN1 100k CIN 10F VIN Figure 52. Typical EN Pin Voltage Divider Figure 52 shows the typical hysteresis of the EN pin. This hysteresis prevents on/off oscillations that can occur due to noise on the EN pin as it passes through the threshold points. Rev. B | Page 16 of 23 12938-054 VIN = 3.8V 2.5 Data Sheet ADP7157 START-UP TIME CURRENT-LIMIT AND THERMAL SHUTDOWN The ADP7157 uses an internal soft start to limit the inrush current when the output is enabled. The start-up time for a 3.3 V output is approximately 1.2 ms from the time the EN active threshold is crossed to when the output reaches 90% of its final value. The ADP7157 is protected against damage due to excessive power dissipation by current and thermal overload protection circuits. The ADP7157 is designed to current limit when the output load reaches 1.8 A (typical). When the output load exceeds 1.8 A, the output voltage is reduced to maintain a constant current limit. The rise time in seconds of the output voltage (10% to 90%) is approximately 0.0012 x CBYP, where CBYP is in microfarads. 3.5 3.0 VOUT (V) 2.5 2.0 1.5 1.0 0 -2 0 2 4 6 8 10 12 14 16 18 20 TIME (ms) 12938-055 EN 1F 4.7F 10F 0.5 Figure 53. Typical Start-Up Behavior with CBYP = 1 F 3.0 2.5 VOUT (V) Current limit and thermal shutdown protections are intended to protect the device against accidental overload conditions. Cases with a hard short from VOUT to ground or an extremely long soft-start timer typically cause the device to experience thermal oscillations between current limit and thermal shutdown. THERMAL CONSIDERATIONS In applications with a low input to output voltage differential, the ADP7157 does not dissipate much heat. However, in applications with high ambient temperature and/or high input voltage, the heat dissipated in the package may become large enough that it causes the junction temperature of the die to exceed the maximum junction temperature of 125C. 3.5 2.0 The junction temperature of the die is the sum of the ambient temperature of the environment and the temperature rise of the package due to the power dissipation, as shown in Equation 2. 1.5 1.0 0 20 40 60 80 100 120 140 160 TIME (ms) 12938-056 EN 10F 47F 100F 0.5 0 -20 When the ADP7157 junction temperature exceeds 150C, the thermal shutdown circuit turns off the output voltage, reducing the output current to zero. Extreme junction temperature can be the result of high current operation, poor circuit board design, or high ambient temperature. A 15C hysteresis is included so that the ADP7157 does not return to operation after thermal shutdown until the on-chip temperature falls below 135C. When the device exits thermal shutdown, a soft start is initiated to reduce the inrush current. Figure 54. Typical Start-Up Behavior with CBYP = 1 F to 100 F REF, BYP, AND VREG PINS REF, BYP, and VREG generate voltages internally (VREF, VBYP, and VREG) that require external bypass capacitors for proper operation. Do not, under any circumstances, connect any loads to these pins, because doing so compromises the noise and PSRR performance of the ADP7157. Using larger values of CBYP, CREF, and CREG is acceptable but can increase the start-up time, as described in the Start-Up Time section. To guarantee reliable operation, the junction temperature of the ADP7157 must not exceed 125C. To ensure that the junction temperature stays below this maximum value, the user must be aware of the parameters that contribute to junction temperature changes. These parameters include ambient temperature, power dissipation in the power device, and thermal resistances between the junction temperature and ambient air (JA). The JA number is dependent on the package assembly compounds used, as well as the amount of copper used to solder the package ground and the exposed pad to the PCB. Rev. B | Page 17 of 23 ADP7157 Data Sheet Table 7 shows typical JA values of the 8-lead SOIC and 10-lead LFCSP packages for various PCB copper sizes. Table 7. Typical JA Values 120 JA (C/W) 10-Lead LFCSP 8-Lead SOIC 130.2 123.8 93.0 90.4 65.8 66.0 55.6 56.6 44.1 45.5 25mm 2 500mm 2 6400mm 2 100 80 60 40 0 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 TOTAL POWER DISSIPATION (W) Device soldered to minimum size pin traces. Figure 55. Junction Temperature vs. Total Power Dissipation for the 10-Lead LFCSP, TA = 25C Table 8. Typical JB Values 140 JB (C/W) 29.1 30.1 TJ MAXIMUM The junction temperature of the ADP7157 is calculated from the following equation: TJ = TA + (PD x JA) (2) where: TA is the ambient temperature. PD is the power dissipation in the die, given by PD = ((VIN - VOUT) x ILOAD) + (VIN x IGND) JUNCTION TEMPERATURE (C) Package 10-Lead LFCSP 8-Lead SOIC 25mm 2 500mm 2 6400mm 2 100 80 60 40 (3) 20 where: VIN and VOUT are the input and output voltages, respectively. ILOAD is the load current. IGND is the ground current. 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 TOTAL POWER DISSIPATION (W) Figure 56. Junction Temperature vs. Total Power Dissipation for the 10-Lead LFCSP, TA = 50C 130 (4) As shown in Equation 4, for a given ambient temperature, input to output voltage differential, and continuous load current, a minimum copper size requirement exists for the PCB to ensure that the junction temperature does not rise above 150C. TJ MAXIMUM 125 JUNCTION TEMPERATURE (C) Power dissipation caused by ground current is quite small and can be ignored. Therefore, the junction temperature equation simplifies to the following equation: TJ = TA + (((VIN - VOUT) x ILOAD) x JA) 120 12938-058 1 12938-057 20 The heat dissipation from the package can be improved by increasing the amount of copper attached to the pins and exposed pad of the ADP7157. Adding thermal planes underneath the package also improves thermal performance. However, as shown in Table 7, a point of diminishing returns is eventually reached, beyond which an increase in the copper area does not yield significant reduction in the junction to ambient thermal resistance. Figure 55 to Figure 60 show junction temperature calculations for different ambient temperatures, power dissipation, and areas of PCB copper. Rev. B | Page 18 of 23 120 25mm 2 115 500mm 2 6400mm 2 110 105 100 95 90 85 80 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 TOTAL POWER DISSIPATION (W) Figure 57. Junction Temperature vs. Total Power Dissipation for the 10-Lead LFCSP, TA = 85C 12938-059 Copper Size (mm2) 251 100 500 1000 6400 TJ MAXIMUM JUNCTION TEMPERATURE (C) Table 8 shows the typical JB values of the 8-lead SOIC and 10-lead LFCSP. 140 Data Sheet ADP7157 Thermal Characterization Parameter (JB) 140 TJ MAXIMUM When board temperature is known, use the thermal characterization parameter, JB, to estimate the junction temperature rise (see Figure 61 and Figure 62). Use the board temperature (TB) and the power dissipation (PD) to calculate the maximum junction temperature (TJ) by JUNCTION TEMPERATURE (C) 120 25mm 2 500mm 2 6400mm 2 100 80 TJ = TB + (PD x JB) 60 (5) The typical JB value is 29.1C/W for the 10-lead LFCSP package and 30.1C/W for the 8-lead SOIC package. 40 20 140 0 120 0.2 0.6 0.4 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 TOTAL POWER DISSIPATION (W) Figure 58. Junction Temperature vs. Total Power Dissipation for the 8-Lead SOIC, TA = 25C 130 TJ MAXIMUM 500mm 2 25mm 2 6400mm 2 110 100 100 80 60 TB = 25C TB = 50C TB = 65C TB = 85C 40 20 90 0 0 80 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 6.0 TOTAL POWER DISSIPATION (W) 70 12938-063 JUNCTION TEMPERATURE (C) 120 JUNCTION TEMPERATURE (C) 0 12938-060 TJ MAXIMUM Figure 61. Junction Temperature vs. Total Power Dissipation for the 10-Lead LFCSP 60 140 50 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 TOTAL POWER DISSIPATION (W) Figure 59. Junction Temperature vs. Total Power Dissipation for the 8-Lead SOIC, TA = 50C 130 TJ MAXIMUM 125 500mm 2 120 6400mm 2 115 100 80 60 TB = 25C TB = 50C TB = 65C TB = 85C 40 105 0 0 100 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 TOTAL POWER DISSIPATION (W) 95 Figure 62. Junction Temperature vs. Total Power Dissipation for the 8-Lead SOIC 90 85 80 0.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 TOTAL POWER DISSIPATION (W) Figure 60. Junction Temperature vs. Total Power Dissipation for the 8-Lead SOIC, TA = 85C Rev. B | Page 19 of 23 12938-064 20 110 12938-062 JUNCTION TEMPERATURE (C) 25mm 2 120 JUNCTION TEMPERATURE (C) 0 12938-061 TJ MAXIMUM 40 ADP7157 Data Sheet PSRR PERFORMANCE The ADP7157 is available in four models that optimize power dissipation and PSRR performance as a function of input and output voltage. See Table 9 and Table 10 for selection guides. It is recommended to select the corresponding product model for a particular output voltage range to achieve optimized PSRR performance. For example, select the ADP7157-04 model for VOUT = 3.3V to achieve >80 dB PSRR (10 Hz to 100 kHz) with 500 mV headroom. When considering a VOUT = 1.8 V case, note that all four product models can generate a 1.8 V output, but the ADP7157-01 model provides the best PSRR performance, though other models, like the ADP7157-04, are still capable of generating 1.8 V output for PSRR relaxed applications. The ADP7157 supports a 2.3 V to 5.5 V input range. Typically, a minimum 500 mV headroom is required to achieve the best PSRR performance above the maximum output voltage (VOUT_MAX) at 1.2 A. For example, ADP7157-04 requires a minimum 3.8 V input voltage to achieve the best PSRR performance for a 3.3 V output at 1.2 A. Table 9. Model Selection Guide for PSRR Model ADP7157-01 ADP7157-02 ADP7157-03 ADP7157-04 VOUT_MAX (V) 1.8 2.3 2.9 3.3 PSRR (dB) at 1.2 A; VIN = VOUT_MAX + 0.5 V 10 kHz 100 kHz 1 MHz 70 78 52 72 70 53 75 78 55 82 72 55 PSRR (dB) at 1.2 A; VIN = VOUT_MAX + 0.6 V 10 kHz 100 kHz 1 MHz 75 85 55 75 83 57 79 94 60 84 86 60 Table 10. Model Selection Guide for Input Voltage Model ADP7157-01 ADP7157-02 ADP7157-03 ADP7157-04 Adjustable VOUT Range (V) 1.2 to 1.8 1.2 to 2.3 1.2 to 2.9 1.2 to 3.3 VOUT Range (V) for Optimized PSRR 1.2 to 1.8 1.8 to 2.3 2.3 to 2.9 2.9 to 3.3 Rev. B | Page 20 of 23 VREG (V) 2.1 2.6 3.2 3.6 VIN Range (V) 2.3 to 5.5 2.8 to 5.5 3.4 to 5.5 3.8 to 5.5 Data Sheet ADP7157 PCB LAYOUT CONSIDERATIONS 12938-066 Place the input capacitor as close as possible to the VIN pin and ground. Place the output capacitor as close as possible to the VOUT pin and ground. Place the bypass capacitors (CREG, CREF, and CBYP) for VREG, VREF, and VBYP close to the respective pins (VREG, REF, and BYP) and ground. The use of a 0805, a 0603, or a 0402 size capacitor achieves the smallest possible footprint solution on boards where area is limited. Maximize the amount of ground metal for the exposed pad, and use as many vias as possible on the component side to improve thermal dissipation. 12938-065 Figure 64. Sample 8-Lead SOIC PCB Layout Figure 63. Sample 10-Lead LFCSP PCB Layout Rev. B | Page 21 of 23 ADP7157 Data Sheet OUTLINE DIMENSIONS 2.48 2.38 2.23 3.10 3.00 SQ 2.90 0.50 BSC 10 6 PIN 1 INDEX AREA 1.74 1.64 1.49 EXPOSED PAD 0.50 0.40 0.30 1 5 SEATING PLANE 0.05 MAX 0.02 NOM COPLANARITY 0.08 0.30 0.25 0.20 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. 02-05-2013-C 0.80 0.75 0.70 0.20 MIN PIN 1 INDICATOR (R 0.15) BOTTOM VIEW TOP VIEW 0.20 REF Figure 65. 10-Lead Lead Frame Chip Scale Package [LFCSP] 3 mm x 3 mm Body and 0.75 mm Package Height (CP-10-9) Dimensions shown in millimeters 5.00 4.90 4.80 2.29 0.356 6.20 6.00 5.80 5 4.00 3.90 3.80 2.29 0.457 4 1 FOR PROPER CONNECTION OF THE EXPOSED PAD, REFER TO THE PIN CONFIGURATION AND FUNCTION DESCRIPTIONS SECTION OF THIS DATA SHEET. BOTTOM VIEW 1.27 BSC 3.81 REF TOP VIEW 1.65 1.25 1.75 1.35 SEATING PLANE 0.51 0.31 0.50 0.25 0.10 MAX 0.05 NOM COPLANARITY 0.10 8 0 45 0.25 0.17 1.04 REF 1.27 0.40 COMPLIANT TO JEDEC STANDARDS MS-012-A A Figure 66. 8-Lead Standard Small Outline Package, with Exposed Pad [SOIC_N_EP] Narrow Body (RD-8-1) Dimensions shown in millimeters Rev. B | Page 22 of 23 06-02-2011-B 8 Data Sheet ADP7157 ORDERING GUIDE Model 1, 2 ADP7157ACPZ-01-R7 ADP7157ACPZ-02-R7 ADP7157ACPZ-03-R7 ADP7157ACPZ-04-R7 ADP7157ARDZ-01-R7 ADP7157ARDZ-02-R7 ADP7157ARDZ-03-R7 ADP7157ARDZ-04-R7 ADP7157CP-04-EVALZ 1 2 Temperature Range -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C -40C to +125C Output Voltage Range (V) 1.2 to 1.8 1.2 to 2.3 1.2 to 2.9 1.2 to 3.3 1.2 to 1.8 1.2 to 2.3 1.2 to 2.9 1.2 to 3.3 Package Description 10-Lead LFCSP 10-Lead LFCSP 10-Lead LFCSP 10-Lead LFCSP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP 8-Lead SOIC_N_EP Evaluation Board Package Option CP-10-9 CP-10-9 CP-10-9 CP-10-9 RD-8-1 RD-8-1 RD-8-1 RD-8-1 Z = RoHS Compliant Part. To order a device with voltage options other than the listed options, contact your local Analog Devices sales or distribution representative. (c)2016 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. D12938-0-11/16(B) Rev. B | Page 23 of 23 Branding LSX LT0 LT1 LT2