GE
Data Sheet
January 20, 2016 ©2016 General Electric Company. All rights reserved.
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
Features
Compliant to RoHS EU Directive 2011/65/EU (-Z
versions)
Compliant to RoHS EU Directive 2011/65/EU under
exemption 7b (Lead solder exemption). Exemption 7b
will expire after June 1, 2016 at which time this product
will no longer be RoHS compliant (non-Z versions)
Delivers up to 25A output current
High efficiency – 93% at 3.3V full load
Small size and low profile:
47.2 mm x 29.4 mm x 8.50 mm
(1.86 in x 1.16 in x 0.335 in)
Low output ripple and noise
Constant switching frequency (500 kHz)
Surface mount or through hole
Output voltage programmable from 0.8 Vdc to 5.5Vdc
via external resistor
Remote On/Off
Remote Sense
Parallel operation with current sharing (-P option)
Output voltage sequencing (multiple modules)
Output overvoltage protection
Overtemperature protection
Output overcurrent protection (non-latching)
Wide operating temperature range (-40°C to 85°C)
UL* 60950-1Recognized, CSA† C22.2 No. 60950-1-03
Certified, and VDE‡ 0805:2001-12 (EN60950-1) Licensed
ISO** 9001 and ISO 14001 certified manufacturing
facilities
Applications
Distributed power architectures
Intermediate bus voltage applications
Telecommunications equipment
Servers and storage applications
Networking equipment
Enterprise Networks
Latest generation IC’s (DSP, FPGA, ASIC) and
Microprocessor powered applications
Options
Baseplate version for heatsink attachment
(-H suffix)
Through Hole version (-L)
Paralleling with current sharing (-P)
Description
The NXA025 series SMT (surface-mount technology) power modules are non-isolated dc-dc converters that can deliver up
to 25A of output current with full load efficiency of 93% at 3.3Vdc output voltage. These modules provide a precisely
regulated output voltage from 0.8Vdc to 5.5Vdc, programmable via an external resistor. Their open-frame construction
and small footprint enable designers to develop cost- and space-efficient solutions. Standard features include remote
On/Off, adjustable output voltage, remote sense, active current sharing between parallel modules, output voltage
sequencing of multiple modules, overcurrent, overvoltage, and overtemperature protection.
* UL is a registered trademark of Underwriters Laboratories, Inc.
† CSA is a registered trademark of Canadian Standards Association.
‡ VDE is a trademark of Verband Deutscher Elektrotechniker e.V.
** ISO is a registered trademark of the International Organization of Standards
RoHS Compliant
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 2
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are absolute stress ratings
only, functional operation of the device is not implied at these or any other conditions in excess of those given in the operations
sections of the data sheet. Exposure to absolute maximum ratings for extended periods can adversely affect the device reliability.
Parameter Device Symbol Min Max Unit
Input Voltage All VIN -0.3 14 Vdc
Continuous
Operating Ambient Temperature All TA -40 85 °C
(see Thermal Considerations section)
Storage Temperature All Tstg -55 125 °C
Electrical Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature conditions.
Parameter Device Symbol Min Typ Max Unit
Operating Input Voltage All VIN 10.0 12.0 14.0 Vdc
Maximum Input Current All IIN,max 14 Adc
(VIN=10.0V to 14.0V, IO=IO, max )
Inrush Transient All I2t 1 A2s
Input Reflected Ripple Current, peak-to-peak
(5Hz to 20MHz, 1μH source impedance; VIN, min to VIN, max, IO=
IOmax ; See Test configuration section)
All 60 mAp-p
Input Ripple Rejection (120Hz) All 50 dB
CAUTION: This power module is not internally fused. An input line fuse must always be used.
This power module can be used in a wide variety of applications, ranging from simple standalone operation to being part of a
complex power architecture. To preserve maximum flexibility, internal fusing is not included, however, to achieve maximum safety
and system protection, always use an input line fuse. The safety agencies require a fast-acting fuse with a maximum rating of 30A
(see Safety Considerations section). Based on the information provided in this data sheet on inrush energy and maximum dc input
current, the same type of fuse with a lower rating can be used. Refer to the fuse manufacturer’s data sheet for further information.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 3
Electrical Specifications (continued)
Parameter Device Symbol Min Typ Max Unit
Output Voltage Set-point All VO, set -1.2 +1.2 % VO, set
(VIN=VN, min, IO=IO, max, TA=25°C)
Output Voltage All VO, set -3.0 +3.0 % VO, set
(Over all operating input voltage, resistive load, and
temperature conditions until end of life)
Adjustment Range All VO 0.7887 5.5 Vdc
Selected by an external resistor
Output Regulation
Line (VIN=VIN, min to VIN, max) All 0.01 0.1 % VO, set
Load (IO=IO, min to IO, max) All 0.1 0.2 % VO, set
Temperature (Tref=TA, min to TA, max) All 0.5 1 % VO, set
Output Ripple and Noise on nominal output
(VIN=VIN, nom and IO=IO, min to IO, max
Cout = 2 * 0.47μF ceramic capacitors)
RMS (5Hz to 20MHz bandwidth) All 5 15 mVrms
Peak-to-Peak (5Hz to 20MHz bandwidth) All 15 50 mVpk-pk
External Capacitance
ESR ≥ 1 mΩ All CO, max 1000 μF
ESR ≥ 10 mΩ All CO, max 10,000 μF
Output Current All Io 0 25 Adc
Output Current Limit Inception (Hiccup Mode ) All IO, lim 125 150 % Io
Output Short-Circuit Current All IO, s/c 1 Adc
(VO≤250mV) ( Hiccup Mode )
Efficiency VO,set = 0.8Vdc η 79.0 %
VIN= VIN, nom, TA=25°C VO, set = 1.2Vdc η 84.7 %
IO=IO, max , VO= VO,set VO,set = 1.5Vdc η 87.3 %
VO,set = 1.8Vdc η 88.9 %
VO,set = 2.0Vdc η 89.7 %
VO,set = 2.5Vdc η 91.4 %
VO,set = 3.3Vdc η 93.1 %
VO,set = 5.5Vdc η 95.1 %
Switching Frequency All fsw 500 kHz
Dynamic Load Response
(dIo/dt=5A/µs; VIN = VIN, nom; TA=25°C) All Vpk 150 mV
Load Change from Io= 50% to 100% of Io,max; No
external output capacitors
Peak Deviation
Settling Time (Vo<10% peak deviation)
All ts 25 µs
(dIo/dt=5A/µs; VIN = VIN, nom; TA=25°C) All Vpk 150 mV
Load Change from Io= 100% to 50%of Io,max: No
external output capacitors
Peak Deviation
Settling Time (Vo<10% peak deviation)
All ts 25 µs
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 4
General Specifications
Parameter Min Typ Max Unit
Calculated MTBF (IO=80% of IO, max, TA=25°C) 2,150,000 Hours
Weight 15.5 (0.55) g (oz.)
Feature Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature conditions. See
Feature Descriptions for additional information.
Parameter Device Symbol Min Typ Max Unit
SEQ/ENA Signal Interface
(VIN=VIN, min to VIN, max ; open collector or equivalent,
Signal referenced to GND)
Logic High (SEQ/ENA pin open – Module Off)
SEQ/ENA Current All ISEQ/ENA 0.5 2.33 mA
SEQ/ENA Voltage: All VSEQ/ENA 3.5 14 V
Logic Low (Module ON)
SEQ/ENA Current: All ISEQ/ENA 200 μA
SEQ/ENA Voltage: All VSEQ/ENA 1.2 V
Turn-On Delay and Rise Times All Tdelay ― 1 ― msec
(IO=IO, max , Vo to within ±1% of steady state) All Trise ― 5 ― msec
Output voltage overshoot – Startup 0.1
0.5
% VO, set
IO=80% of IO, max; VIN = 12Vdc, TA = 25 oC
Ouptut Overvoltage Protection (Latching) All 5.62 5.8 6.0 V
Input Undervoltage Lockout
Turn-on Threshold All 9.9 V
Turn-off Threshold All 8.1 V
Remote Sense Range ― ― 0.5 V
Overtemperature Protection
All Tref 125 °C
(See Thermal Consideration section)
Forced Load Share Accuracy All 10 % Io
Number of units in Parallel 5
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 5
Characteristic Curves
The following figures provide typical characteristics for the NXA025A0X –S at 25ºC.
EFFICIENCY, η (%)
80%
81%
82%
83%
84%
85%
86%
87%
88%
0 5 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
EFFICIENCY, η (%)
88%
89%
90%
91%
92%
93%
94%
0 5 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
OUTPUT CURRENT, I
O
(A)
OUTPUT CURRENT, I
O
(A)
Figure 1. Converter Efficiency versus Output Current
(Vout = 1.2Vdc).
Figure 4. Converter Efficiency versus Output Current
(Vout = 2.5Vdc).
EFFICIENCY, η (%)
83%
84%
85%
86%
87%
88%
89%
90%
91%
05 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
EFFICIENCY, η (%)
88%
89%
90%
91%
92%
93%
94%
95%
0 5 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
OUTPUT CURRENT, I
O
(A)
OUTPUT CURRENT, I
O
(A)
Figure 2. Converter Efficiency versus Output Current
(Vout = 1.5Vdc).
Figure 5. Converter Efficiency versus Output Current
(Vout = 3.3Vdc).
EFFICIENCY, η (%)
85%
86%
87%
88%
89%
90%
91%
92%
0 5 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
EFFICIENCY, η (%)
89%
90%
91%
92%
93%
94%
95%
96%
97%
0 5 10 15 20 25
Vin=13.2V
Vin=10.8V
Vin=12.0V
OUTPUT CURRENT, I
O
(A)
OUTPUT CURRENT, I
O
(A)
Figure 3. Converter Efficiency versus Output Current
(Vout
= 1.8Vdc).
Figure 6. Converter Efficiency versus Output Current
(Vout = 5.0Vdc).
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 6
Characteristic Curves (continued)
The following figures provide typical characteristics for the NXA025A0X –S at 25ºC.
OUTPUT VOLTAGE
VO (V) (20mV/div)
OUTPUT CURRENT, OUTPUT VOLTAGE
IO (A) (5A/div) VO (V) (50mV/div)
TIME, t (1µs/div)
TIME, t (5 µs/div)
Figure 7. Typical Output Ripple and Noise (Vin = 12V dc, Vo
= 3.3 Vdc, Cout = 2x 0.47uF ceramic capacitor).
Figure 10. Transient Response to Dynamic Load Change
from 100% to 50% of full load (Vo = 3.3Vdc).
OUTPUT VOLTAGE
VO (V) (20mV/div)
OUTPUT VOLTAGE, INPUT VOLTAGE
Vo (V) (1V/div) VIN (V) (2V/div)
TIME, t (1µs/div)
TIME, t (0.5ms/div)
Figure 8. Typical Output Ripple and Noise (Vin = 12V dc, Vo
= 1.2Vdc, Cout = 2x 0.47uF ceramic capacitor).
Figure 11. Typical Start-Up with application of Vin (Vo =
3.3Vdc).
OUTPUT CURRENT OUTPUT VOLTAGE IO (A)
(5A/div) VO (V) (50mV/div)
OUTPUT VOLTAGE On/Off VOLTAGE
VOV) (1V/div) VOn/off (V) (2V/div)
TIME, t (5µs/div)
TIME, t (0.5ms/div)
Figure 9. Transient Response to Dynamic Load Change
from 50% to 100% of full load (Vo = 3.3Vdc).
Figure 12. Typical Start-Up Using Enable (Vo = 3.3Vdc).
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 7
Characteristic Curves (continued)
The following figures provide typical characteristics for the NXA025A0X –S at 25oC.
Module # 1 Module #2
VO(V) (1V/div) VO (V) (1V/div)
TIME, t (1ms/div)
Figure 13. Synchronized Start-up of Output Voltage when
SEQ/ENA pins are tied together (Module #1 = 1.5Vdc,
Module #2 = 3.3Vdc).
Module # 1 Module #2
VO(V) (1V/div) VO (V) (1V/div)
TIME, t (1ms/div)
Figure 14. Synchronized Shut-down of Output Voltage
when SEQ/ENA pins are tied together (Module #1 = 1.5Vdc,
Module #2 = 3.3Vdc).
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 8
Characteristic Curves (continued)
The following figures provide typical thermal derating curves for NXA025A0X –S (Figures 19 and 20 show derating curves with base
plate).
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
1
00LFM
200LFM
300LFM
400LFM
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
100LFM
200LFM
300LFM
400LFM
AMBIENT TEMPERATURE, T
A
OC
AMBIENT TEMPERATURE, T
A
OC
Figure 15. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=1.2Vdc).
Figure 18. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=5.0 Vdc).
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
1
00LFM
200LFM
300LFM
400LFM
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
200 LFM
100 LFM
AMBIENT TEMPERATURE, T
A
OC
AMBIENT TEMPERATURE, T
A
OC
Figure 16. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=1.8 Vdc).
Figure 19. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=3.3 Vdc) with
baseplate.
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
100LFM
200LFM
300LFM
400LFM
OUTPUT CURRENT, Io (A)
0
5
10
15
20
25
30
20 30 40 50 60 70 80
200 LFM
100 LFM
300 LFM
400 LFM
AMBIENT TEMPERATURE, TA OC
AMBIENT TEMPERATURE, TA OC
Figure 17. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=3.3 Vdc).
Figure 20. Derating Output Current versus Local Ambient
Temperature and Airflow (Vin = 12Vdc, Vo=5.0 Vdc) with
baseplate.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 9
Test Configurations
TO OSCILLOSCOPE
CURRENT PROBE
L
TEST
1μH
BATTERY
C
S
220μF
E.S.R.<0.1Ω
@ 20°C 100kHz
Min
150μF
V
IN
(+)
COM
NOTE: Measure input reflected ripple current with a simulated
source inductance (L
TEST
) of 1μH. Capacitor C
S
of fsets
possible battery impedance. Measure current as shown
above.
C
IN
Figure 21. Input Reflected Ripple Current Test Setup.
NOTE: All voltage measurem ents to be taken at the module
terminals, as shown above. If sockets are used then
Kelvin connections are required at the module terminals
to avoid measurement errors due to socket contact
resistance.
V
O
(+)
COM
1uF
.
RESISTIVE
LOAD
SCOPE
COPPER STRIP
GROUND PLANE
10uF
Figure 22. Output Ripple and Noise Test Setup.
V
O
COM
V
IN
(+)
COM
R
LOAD
R
contact
R
distribution
R
contact
R
distribution
R
contact
R
contact
R
distribution
R
distribution
V
IN
V
O
NOTE: All voltage measurements to be taken at the module
terminals, as shown above. If sockets are used then
Kelvi n c onnec ti ons are r equ ired at the m odu l e t ermi n als
to avoi d m eas urem en t errors du e t o s oc k et c ontact
resistance.
Figure 23. Output Voltage and Efficiency Test Setup.
η
=
V
O
.
I
O
V
IN
.
I
IN
x
100
%
Efficiency
Typical Application Circuit
Vout
Qx
Rx
4.99k
Dx
Share
SEN+
SEQ/ENA
SEN-
GND
GND
GND
Vin
Vin
Vout
Vout
V
IN
C
IN
Cout
Share
1uF
Rtrim
Figure 24. Application Schematic
Design Considerations
Input Source Impedance
The power module should be connected to a low-impedance
source. Highly inductive source impedance can affect the
stability of the power module. The input capacitor CIN should
be located equal distance from the two input pins of the
module. CIN is recommended to be 150μF minimum. The ripple
voltage is 50mV RMS at 1MHz and the capacitor should be
chosen with an ESR and an RMS Current Rating for this amount
of ripple voltage. When using multiple modules in parallel, a
small inductor (0.2 –0.5μH) is recommended at the input of
each module to prevent interaction between modules. Consult
the factory for further application guidelines.
Safety Considerations
For safety agency approval the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standards, i.e., UL
60950-1, CSA C22.2 No. 60950-1-03, and VDE 0850:2001-12
(EN60950-1) Licensed.
For the converter output to be considered meeting the
requirements of safety extra-low voltage (SELV), the input must
meet SELV requirements. The power module has extra-low
voltage (ELV) outputs when all inputs are ELV.
The input to these units is to be provided with a maximum of
30 A fast-acting fuse in the ungrounded lead.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 10
Feature Description
Remote On/Off using SEQ/ENA Pin
The NXA025A0X-S SMT power modules feature an SEQ/ENA pin
for remote On/Off operation. If not using the remote On/Off
pin, leave the pin open (module will be on). The SEQ/ENA signal
(VSEQ/ENA) is referenced to ground. Circuit configuration for
remote On/Off operation of the module using SEQ/ENA pin is
shown in Figure 25.
During Logic High on the SEQ/ENA pin (transistor Qx is OFF), the
module remains OFF. The external resistor Rx should be
chosen to maintain 3.5V minimum on the SEQ/ENA pin to
insure that the unit is OFF when transistor Qx is in the OFF
state. During Logic-Low when Qx is turned ON, the module is
turned ON. Note that the external diode is required to make
sure the internal thermal shutdown (THERMAl_SD) and
undervoltage (UVLO) circuits are not disabled when Qx is
turned ON
V
IN
R
2
R
1
Qx
1k
4.99k
Enable
UVLO
THERMAL_SD
SEQ/ENA
Pin
Rx
4.99k
Dx
Figure 25. Remote On/Off Implementation.
The SEQ/ENA pin can also be used to synchronize the output
voltage start-up and shutdown of multiple modules in parallel.
By connecting SEQ/ENA pins of multiple modules, the output
start-up can be synchronized (please refer to characterization
curves). When SEQ/ENA pins are connected together, all
modules will shutdown if any one of the modules gets disabled
due to undervoltage lockout or overtemperature protection.
Remote Sense
Remote sense feature minimizes the effects of distribution
losses by regulating the voltage at the remote sense pins. The
voltage between the remote sense pins and the output
terminals must not exceed the remote sense range given in the
Feature Specification table, i.e.:
[Vo(+) – Vo(GND)] –[SENSE(+) – SENSE(-)] < 0.5V
Remote sense configuration is shown in Figure 26. If not using
the remote sense feature to regulate the output voltage at the
point of load, connect SENSE (+) to Vo(+) and Sense (-) to
ground. The amount of power delivered by the module is
defined as the voltage at the output terminals multiplied by the
output current. When using the remote sense, the output
voltage of the module can be increased, which at the same
output current would increase the power output of the module.
Ensure that the maximum output power of the module remains
at or
below the maximum rated power (Po,max = Io,max x Vo,max).
Figure 26. Effective Circuit Configuration for Remote
sense operation
Overcurrent Protection
To provide protection in a fault (output overload) condition, the
unit is equipped with internal current-limiting circuitry and can
endure current limiting continuously. At the point of
current-limit inception, the unit enters hiccup mode. The unit
operates normally once the output current is brought back into
its specified range. The average output current during hiccup is
10% IO, max.
Input Undervoltage Lockout
At input voltages below the input undervoltage lockout limit,
module operation is disabled. The module will begin to operate
at an input voltage above the undervoltage lockout turn-on
threshold.
Overtemperature Protection
To provide protection in a fault condition, the unit is
equipped with a thermal shutdown circuit. The unit will
shutdown if the thermal reference point Tref, exceeds 125oC
(typical), but the thermal shutdown is not intended as a
guarantee that the unit will survive temperatures beyond its
rating. The module will automatically restarts after it cools
down.
Output Voltage Programming
The output voltage of the NXA025A0X-S can be programmed
to any voltage from 0.8Vdc to 5.5Vdc by inserting a series
resistor (shown as Rtrim in figure 27) in the Sense(+) pin of the
module. Without an external resistor in the Sense(+) pin (Sense
(+) pin is shorted to Vo(+)), the output voltage of the module will
be 0.7887V. With Sense(+) not connected to Vo(+), the output of
the module will reach overvoltage shutdown. A 1μF multi-layer
ceramic capacitor is required from Rtrim to Sense(-) pin to
minimize noise. To calculate the value of the
Feature Descriptions (continued)
Output Voltage Programming (continued)
resistor Rtrim for a particular desired voltage Vo, use the
following equation:
Ω
−= 1
7887.0
*775 Vo
Rtrim
Where Vo is the desired output voltage
and Rtrim is the external resistor in ohms
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 11
For example, to program the output voltage of the
NXA025A0X-S module to 2.5Vdc, Rtrim is calculated as follows:
−= 1
7887.0 5.2
*775Rtrim
Ω=1682Rtrim
V
O
COM
V
IN
(+)
COM
R
LOAD
R
trim
Sense+
Sense-
1µF
ENA
Share
Figure 27. Circuit Configuration for Programming
Output voltage
Table 1 provides Rtrim values required for most common
output voltages. To achieve the output voltage tolerance as
specified in the electrical specifications over all operating input
voltage, resistive load and temperature conditions, use 0.1%
thick metal film resistor.
Table 1
Vo,set
(V)
Rtrim
Ω
0.8
11
1.0
208
1.2
404
1.5
699
1.8
994
2.0
1190
2.5
1682
3.3
2468
5.0
4138
Overvoltage Shutdown
Open
Forced Load sharing (Parallel Operation)
For additional power requirements, the power module can be
configured for parallel operation with forced load sharing (See
Figure 28). Good layout techniques should be observed for
noise immunity when using multiple units in parallel. To
implement forced load sharing, the following connections
should be made:
• The share pins of all units in parallel must be connected
together. The path of these connections should be as
direct as possible.
• All remote-sense pins should be connected to the power
bus at the same point, i.e., connect all the SENSE(+) pins to
the (+) side of the bus and all the SENSE(-) pins to the
GROUND of the power bus at the same point. Close
proximity and directness are necessary for good noise
immunity
The share bus is not designed for redundant operation and the
system will be non-functional upon failure of one of the unit
when multiple units are in parallel. The maximum number of
modules tied to share bus is 5. When not using the parallel
feature, leave the share pin open.
Figure 28. Circuit Configuration for modules in parallel.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 12
Thermal Considerations
The power modules operate in a variety of thermal
environments; however, sufficient cooling should be provided
to help ensure reliable operation.
Considerations include ambient temperature, airflow, module
power dissipation, and the need for increased reliability. A
reduction in the operating temperature of the module will
result in an increase in reliability. The thermal data presented
here is based on physical measurements taken in a wind
tunnel.
The thermal reference point, Tref used in the specifications is
shown in Figure 29. For reliable operation this temperature
should not exceed 110oC.
Please refer to the Application Note “Thermal Characterization
Process For Open-Frame Board-Mounted Power Modules” for a
detailed discussion of thermal aspects including maximum
device temperatures.
Tref
Tref
Figure 29. Tref Temperature measurement location.
Heat Transfer via Convection
Increased airflow over the module enhances the heat transfer
via convection. Derating figures showing the maximum output
current that can be delivered by various module versus local
ambient temperature (TA) for natural convection and up to
2m/s (400 ft./min) are shown in the respective Characteristics
Curves section.
Base-Plate option (-H)
The baseplate option (-H) power modules are constructed with
baseplate on topside of the open frame power module. The
baseplate includes two through-threaded, M3 x 0.5 mounting
hole pattern, which enable heat sinks or cold plates to attach
to the module. The mounting torque must not exceed 0.56 N-
m (5 in.-lb.) during heat sink assembly. The baseplate option
allows customers to operate the module in an extreme thermal
environment with attachment of heatsink/cold-plate for proper
cooling of internal component to heighten reliable and
consistent operation. The thermal reference point for
baseplate option is center of the heat plate on the top-side.
For reliable operation this temperature should not exceed
105oC.
Layout Considerations
The input capacitors should be located equal distance from the
two input pins of the module. Recommended layout is shown
in the mechanical section. In addition to the input and output
planes, a ground plane beneath the module is recommended.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 13
Mechanical Outline for NXA025A0X-S
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
Top View
Side View
Bottom View
Pin #
Function
1
Ground
2
Vout
3
Ground
4
Vout
5
Ground
6
Vin
7
SHARE
8
Sen+
9
SEQ/ENA
10
Sen-
11
Vin
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 14
Mechanical Outline for NXA025A0X-HS
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
Top View
Side View
Bottom View
Pin #
Function
1
Ground
2
Vout
3
Ground
4
Vout
5
Ground
6
Vin
7
SHARE
8
Sen+
9
SEQ/ENA
10
Sen-
11
Vin
For additional heat sink Attachm ent:
Accepts M3x0.5 carbon steel screws
Insertion i n to ba seplate n o t to exceed
4.55 mm [0.175 in ] .
Max Torque = 5 IN-LBS
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 15
Recommended Pad Layout
Dimensions are in millimeters and inches.
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
Layout Guidelines
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 16
Mechanical Outline for NXA025A0X-L
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
Top View
Side View
Bottom View
Pin #
Function
1
Ground
2
Vout
3
Ground
4
Vout
5
Ground
6
Vin
7
SHARE
8
Sen+
9
SEQ/ENA
10
Sen-
11
Vin
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 17
Recommended Pad Layout for NXA025A0X-L (Through Hole Version)
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.) [unless otherwise indicated]
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
x.xx mm ± 0.25 mm (x.xxx in ± 0.010 in.)
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 18
Surface Mount Information
Packaging Details
The surface mount versions of the NXA025-S series modules
are supplied as standard in the plastic tray shown in Figure
30. The tray has external dimensions of 136mm (W) x
322.6mm (L) x 18.4mm (H) or 5.35in (W) x 12.7in (L) x 0.72in
(H).
Figure 30. Surface Mount Packaging Tray
Tray Specification
Material Antistatic coated PVC
Max temperature 65oC
Max surface resistivity 1012Ω/sq
Color Clear
Capacity 15 power modules
Min order quantity 45 pcs (1box of 3 full trays)
Each tray contains a total of 15 power modules. The trays
are self-stacking and each shipping box will contain 3 full
trays plus one empty hold down tray giving a total number
of 45 power modules.
Pick and Place
The NXA025-S series of DC-to-DC power modules use an
open-frame construction and are designed for surface
mount assembly within a fully automated manufacturing
process.
The NXA025-S series modules are fitted with two Kapton
labels designed to provide a large flat surface for pick and
placing. The labels are located covering the Center of
Gravity of the power module. The labels meets all the
requirements for surface-mount processing, as well as
meeting UL safety agency standards. The labels will
withstand reflow temperatures up to 300°C. The labels also
carry product information such as product code, date and
location of manufacture. One of the two labels may be used
as a pick-and-place location.
Figure 31. Pick and Place Location.
Nozzle Recommendations
The module weight has been kept to a minimum by using
open frame construction. Even so, they have a relatively
large mass when compared with conventional SMT
components. Variables such as nozzle size, tip style,
vacuum pressure and placement speed should be
considered to optimize this process. The minimum
recommended nozzle diameter for reliable operation is
6mm. The maximum nozzle outer diameter, which will safely
fit within the allowable component spacing, is 9 mm.
Oblong or oval nozzles up to 11 x 9 mm may also be used
within the space available.
For further information please contact your local GE
technical representative.
Surface Mount Information (continued)
Reflow Soldering Information
These NXA025series power modules are large mass, low
thermal resistance devices and typically heat up slower than
other SMT components. It is recommended that the
customer review data sheets in order to customize the
solder reflow profile for each application board assembly.
The following instructions must be observed when SMT
soldering these units. Failure to observe these instructions
may result in the failure of or cause damage to the modules,
and can adversely affect long-term reliability.
These surface mountable modules use our newest SMT
technology called “Column Pin” (CP) connectors. Fig 32
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 19
shows the new CP connector before and after reflow
soldering onto the end-board assembly.
Figure 32. Column Pin Connector Before and After Reflow
Soldering.
The CP is constructed from a solid copper pin with an
integral solder ball attached, which is composed of tin/lead
(Sn/Pb) solder. The CP connector design is able to
compensate for large amounts of co-planarity and still
ensure a reliable SMT solder joint.
Typically, the eutectic solder melts at 183oC, wets the land,
and subsequently wicks the device connection. Sufficient
time must be allowed to fuse the plating on the connection
to ensure a reliable solder joint. There are several types of
SMT reflow technologies currently used in the industry.
These surface mount power modules can be reliably
soldered using natural forced convection, IR (radiant
infrared), or a combination of convection/IR. For reliable
soldering the solder reflow profile should be established by
accurately measuring the modules CP connector
temperatures.
REFLOW TEMP (°C)
REFLOW TIME (S)
Figure 32. Recommended Reflow Profile.
MAX TEMP SOLDER (°C)
TIME LIMIT (S)
Figure 33. Time Limit Curve Above 205oC Reflow.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
January 20, 2016 ©2016 General Electric Company. All rights reserved. Page 20
Surface Mount Information (continued)
Lead Free Soldering
The –Z version Naos SMT modules are lead-free (Pb-free)
and RoHS compliant and are both forward and backward
compatible in a Pb-free and a SnPb soldering process.
Failure to observe the instructions below may result in the
failure of or cause damage to the modules and can
adversely affect long-term reliability.
Pb-free Reflow Profile
Power Systems will comply with J-STD-020 Rev. C
(Moisture/Reflow Sensitivity Classification for Nonhermetic
Solid State Surface Mount Devices) for both Pb-free solder
profiles and MSL classification procedures. This standard
provides a recommended forced-air-convection reflow
profile based on the volume and thickness of the package
(table 4-2). The suggested Pb-free solder paste is Sn/Ag/Cu
(SAC). The recommended linear reflow profile using
Sn/Ag/Cu solder is shown in Fig. 34.
MSL Rating
The Naos SMT modules have a MSL rating of 3.
Storage and Handling
The recommended storage environment and handling
procedures for moisture-sensitive surface mount packages
is detailed in J-STD-033 Rev. A (Handling, Packing, Shipping
and Use of Moisture/Reflow Sensitive Surface Mount
Devices). Moisture barrier bags (MBB) with desiccant are
required for MSL ratings of 2 or greater. These sealed
packages should not be broken until time of use. Once the
original package is broken, the floor life of the product at
conditions of ≤ 30°C and 60% relative humidity varies
according to the MSL rating (see J-STD-033A). The shelf life
for dry packed SMT packages will be a minimum of 12
months from the bag seal date, when stored at the following
conditions: < 40° C, < 90% relative humidity.
Post Solder Cleaning and Drying Considerations
Post solder cleaning is usually the final circuit-board
assembly process prior to electrical board testing. The result
of inadequate cleaning and drying can affect both the
reliability of a power module and the testability of the
finished circuit-board assembly. For guidance on
appropriate soldering, cleaning and drying procedures, refer
to Board Mounted Power Modules: Soldering and Cleaning
Application Note (AP01-056EPS).
Per J-STD-020 Rev. C
0
50
100
150
200
250
300
Reflow Time (Seconds)
Ref low Temp (°C )
Heating Zone
1°C/Second
Peak Temp 260°C
* Min. Time Above 235°C
15 Seconds
*Time Above 217°C
60 Seconds
Cooling
Zone
Figure 34. Recommended linear reflow profile using
Sn/Ag/Cu solder.
GE
Data Sheet
NaosTM NXA025: SMT Non-Isolated DC-DC Power Module
10Vdc – 14Vdc input; 0.8Vdc to 5.5Vdc output; 25A Output Current
Contact Us
For more information, call us at
USA/Canada:
+1 877 546 3243, or +1 972 244 9288
Asia-Pacific:
+86.021.54279977*808
Europe, Middle-East and Africa:
+49.89.878067-280
www.gecriticalpower.com
GE Critical Power reserves the right to make changes to the product(s) or information contained herein without notice, and no
liability is assumed as a result of their use or application. No rights under any patent accompany the sale of any such product(s)
or information.
January 20, 2016 ©2016 General Electric Company. All International rights reserved. Version 1.54
Ordering Information
Please contact your GE Sales Representative for pricing, availability and optional features.
Table 2. Device Codes
Product codes Input Voltage Output Voltage
Output
Current
Efficiency
3.3V @ 25A
Connector
Type
Comcodes
NXA025A0X-S 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT 108975053
NXA025A0X-HS 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT 108975061
NXA025A0X-L 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % TH 108988515
NXA025A0X-LP 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % TH CC109101350
NXA025A0X-SP 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT CC109101342
NXA025A0X-LPZ 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % TH CC109106746
NXA025A0X-SZ 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT 109100402
NXA025A0X-HSZ 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT 109100393
NXA025A0X-LZ 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % TH CC109107174
NXA025A0X-SPZ 10 – 14 Vdc 0.8Vdc – 5.5Vdc 25 A 93 % SMT CC109133682
-Z refers to RoHS-compliant versions.
