NOT RECOMMENDED FOR NEW DESIGN CONTACT US PAM2320 3A LOW NOISE STEP-DOWN DC-DC CONVERTER Description Pin Assignments The PAM2320 is a 3A step-down DC-DC converter. At heavy load, the constant-frequency PWM control performs excellent stability and transient response. No external compensation components are required. The PAM2320 supports a range of input voltages from 2.7V to 5.5V, allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH cell, and other standard power sources. The output voltage is adjustable from 0.6V to the input voltage. The PAM2320 employs internal power switch and synchronous rectifier to minimize external part count and realize high efficiency. During shutdown, the input is disconnected from the output and the shutdown current is less than 1A. Other key features include over-temperature and short circuit protection, and under-voltage lockout to prevent deep battery discharge. The PAM2320 delivers 3A maximum output current while consuming only 42A of no-load quiescent current. Ultra-low RDS(ON) integrated MOSFETs and 100% duty cycle operation make the PAM2320 an ideal choice for high output voltage, high current applications which require a low dropout threshold. Applications The PAM2320 is available in PSOP-8 package. * 5V or 3.3V Point of Load Conversion * * * * * Telecom/Networking Equipment Set Top Boxes Storage Equipment Video Cards DDR Power Supply Features * * Output Current: Up to 3A Output Voltage: 0.6V to VIN * * * * * * * * * * * Input Voltage: 2.7 to 5.5V Efficiency up to 95% 42A (typ) No Load Quiescent Current Shutdown Current: <1A 100% Duty Cycle Operation 1.5MHz Switching Frequency Internal Soft Start No external Compensation Required Current Limit Protection Thermal Shutdown PSOP-8 Package PAM2320 Document number: DS36405 Rev. 3 - 3 1 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Typical Applications Circuit V O = 0.6 x 1 + R1 R 2 Pin Descriptions Pin Number PSOP-8 Pin Name 1 2 3 4 5 6 NC VIN SW GND FB NC 7 EN 8 NC Function Not Connected. Bias supply. Chip main power supply pin. The drains of the internal main and synchronous power MOSFET. Ground Feedback voltage to internal error amplifier, the threshold voltage is 0.6V. Not Connected. Enable control input. Force this pin voltage above 1.5V, enables the chip, and below 0.3V shuts down the device. Not Connected. Functional Block Diagram PAM2320 Document number: DS36405 Rev. 3 - 3 2 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Absolute Maximum Ratings (@TA = +25C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Rating Unit Input Voltage VIN Parameter 6 V SW Pin Voltage -0.3 to (VIN +0.3) V FB Pin Voltage -0.3 to (VIN +0.3) V -0.3 to +6.0 +150 -65 to +150 +300, 5sec V C C C EN Pin Voltage Maximum Junction Temperature Storage Temperature Range Soldering Temperature Recommended Operating Conditions (@TA = +25C, unless otherwise specified.) Parameter Supply Voltage Junction Temperature Range Ambient Temperature Range Rating Unit 2.7 to 5.5 -40 to +125 -40 to +85 V C Thermal Information Parameter Symbol Package Max Thermal Resistance (Junction to Ambient) JA PSOP-8 90 Thermal Resistance (Junction to Case) JC PSOP-8 14 Internal Power Dissipation (@TA= +25C) PD PSOP-8 1100 PAM2320 Document number: DS36405 Rev. 3 - 3 3 of 12 www.diodes.com Unit C/W mW February 2020 (c) Diodes Incorporated PAM2320 Electrical Characteristics (@TA = +25C, VIN = 3.6V, VO = 1.8V, CIN = 22F, CO = 22F, L = 2.2H, unless otherwise specified.) Parameter Input Voltage Range Output Voltage Range UVLO Threshold Symbol Min Typ Max Units VIN -- 2.7 -- 5.5 V VO -- 0.6 -- VIN V VIN Rising -- 2.4 2.5 V Hysteresis -- 240 -- mV VIN Falling 1.8 -- -- V % VUVLO Test Conditions Regulated Output Voltage Accuracy VO IO = 0 to 3A Regulated Feedback Voltage VFB -- -3 -- +2 0.591 0.600 0.609 FB Leakage Current IFB V VO =1V -- -- 0.2 A -- %/V %/A Output Voltage Line Regulation LNR VIN = 2.5V to 5V -- 0.2 Output Voltage Load Regulation LDR IO = 0A to 3A -- 0.5 -- Quiescent Current IQ No Load -- 42 90 A Shutdown Current ISD VEN = 0V -- -- 1 A Current Limit ILIM -- -- 4 -- A Oscillator Frequency fOSC -- 1.2 1.5 1.8 MHz -- -- -- 0.85 60 95 -- -- 95 m m % RDS(ON) -- High Efficiency -- Analog Soft-Start Time tS Drain-Source On-State Resistance High Side Low Side From enable to output regulation -- 0.5 3 ms EN Threshold High VEH -- 1.5 -- -- V EN Threshold Low VEL -- EN Leakage Current IEN VIN = VEN = 0V Over Temperature Protection OTP Hysteresis PAM2320 Document number: DS36405 Rev. 3 - 3 OTP OTH -- -- 4 of 12 www.diodes.com -- -- 0.3 V -1.0 -- +1.0 A -- -- +150 +30 -- -- C C February 2020 (c) Diodes Incorporated PAM2320 Typical Performance Characteristics (@TA = +25C, CIN = 33F, CO = 22F, unless otherwise specified.) Efficiency vs Input Voltage (VO=1.2V) Efficiency vs Input Voltage (VO=1.8V) Efficiency vs Input Voltage (VO=3.3V) PAM2320 Document number: DS36405 Rev. 3 - 3 5 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Typical Performance Characteristics (continued) (@TA = +25C, CIN = 33F, CO = 22F, unless otherwise specified.) PAM2320 Document number: DS36405 Rev. 3 - 3 6 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Typical Performance Characteristics (continued) (@TA = +25C, CIN = 33F, CO = 22F, unless otherwise specified.) PAM2320 Document number: DS36405 Rev. 3 - 3 7 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Application Information The basic PAM2320 application circuit is shown in Page 2. External component selection is determined by the load requirement, selecting L first and then CIN and COUT. Inductor Selection For most applications, the value of the inductor will fall in the range of 1H to 3.3H. Its value is chosen based on the desired ripple current and efficiency. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation 3A reasonable starting point for setting ripple current is IL = 1.2A (40% of 3A). IL = 1 - V OUT VIN 1 Equation (1) (f )(L ) VOUT The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation. Thus, a 4.2A rated inductor should be enough for most applications (3A + 1.2A). For better efficiency, choose a low DC-resistance inductor. VO 1.2V 1.5V 1.8V 2.5V 3.3V L 1H 1.5H 2.2H 2.2H 3.3H CIN and COUT Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: CIN required IRMS IOMAX [VOUT (VIN - VOUT )]1/ 2 VIN This formula has a maximum at VIN = 2VOUT, where IRMS =IOUT /2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR). Typically, once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE (P-P) requirement. The output ripple VOUT is determined by: V OUT IL (ESR + 1 / 8f COUT ) Where f = operating frequency, COUT = output capacitance and IL = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since IL increases with input voltage. Using Ceramic Input and Output Capacitors Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Using ceramic capacitors can achieve very low output ripple and small circuit size. When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size. Thermal Consideration Thermal protection limits power dissipation in the PAM2320. When the junction temperature exceeds +150C, the OTP (Over Temperature Protection) starts the thermal shutdown and turns the pass transistor off. The pass transistor resumes operation after the junction temperature drops below +120C. For continuous operation, the junction temperature should be maintained below +125C. The power dissipation is defined as: PD = IO 2 V O RDS(ON)H + (VIN - V O )RDS(ON)L VIN + (tSW FS IO + IQ ) VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. PAM2320 Document number: DS36405 Rev. 3 - 3 8 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Application Information (continued) For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PD = IO 2 RDS(ON)H + IQ VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surrounding airflow and temperature difference between junction and ambient. The maximum power dissipation can be calculated by the following formula: PD = T J(MAX ) - T A JA Where TJ(max) is the maximum allowable junction temperature +125C. TA is the ambient temperature and JA is the thermal resistance from the junction to the ambient. Based on the standard JEDEC for a two layers thermal test board, the thermal resistance JA of SOP-8(EP) 90C/W respectively. The maximum power dissipation at TA = +25C can be calculated by following formula: PD = (125C - 25C) /90C/W = 1.11W (SOP-8) Setting the Output Voltage The internal reference is 0.6V (Typical). The output voltage is calculated as below: The output voltage is given by Table 1. R1 V O = 0 .6 x 1 + R 2 Table 1: Resistor selection for output voltage setting. VO R1 R2 1.2V 1.5V 1.8V 2.5V 3.3V 150k 225k 300k 475k 680k 150k 150k 150k 150k 150k 100% Duty Cycle Operation As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage is equal to the input voltage minus the voltage drop across the P-Channel transistor: V OUT = VIN - ILOAD (RDSON + RL ) where RDS(ON) = P-Channel switch ON resistance, ILOAD = Output Current, RL = Inductor DC Resistance UVLO and Soft-Start The reference and the circuit remain reset until the VIN crosses its UVLO threshold. The PAM2320 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. The soft-start make the output voltage rise up smoothly. Short Circuit Protection The switch peak current is limited cycle-by-cycle to a typical value of 4A. In the event of an output voltage short circuit, the device operates with a frequency of 500kHz and minimum duty cycle, therefore the average input current is more smaller than current limit. Thermal Shutdown When the die temperature exceeds +150C, a reset occurs and the reset remains until the temperature decrease to +120C, at which time the circuit can be restarted. PAM2320 Document number: DS36405 Rev. 3 - 3 9 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Ordering Information PAM2320 X X X xxx X Pin Configuration B Type: 8 Pins Part Number PAM2320BECADJR Package Type E: PSOP-8 Number of Pins Output Voltage C: 8 ADJ: Adjustable R: Tape & Reel Output Voltage ADJ Package Type PSOP-8 Shipping Package Standard Package 25000 Units/Tape & Reel Marking Information PAM2320 Document number: DS36405 Rev. 3 - 3 10 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 Package Outline Dimensions (All dimensions in mm.) Please see http://www.diodes.com/package-outlines.html for the latest version. (1) Package Type: PSOP-8 PAM2320 Document number: DS36405 Rev. 3 - 3 11 of 12 www.diodes.com February 2020 (c) Diodes Incorporated PAM2320 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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Copyright (c) 2020, Diodes Incorporated www.diodes.com PAM2320 Document number: DS36405 Rev. 3 - 3 12 of 12 www.diodes.com February 2020 (c) Diodes Incorporated