Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 1
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
Brick
40 Amp, No Heatsink, Isolated DC/DC Converter
The PQ60025QTA40 PowerQor™ Tera quarter-brick
converter is a next-generation, board-mountable,
isolated, fixed switching frequency DC/DC converter
that uses synchronous rectification to achieve extremely
high conversion efficiency. The power dissipated by the
converter is so low that a heatsink is not required,
which saves cost, weight, height, and application effort.
All of the power and control components are mounted
to the multi-layer PCB substrate with high-yield surface
mount technology. Since the PowerQor converter has
no explicit thermal connections, it is extremely reliable.
The Tera series offers the maximum useable output cur-
rent for any standard “quarter-brick” module.
PQ60025QTA40 Module
Mechanical Features
• Industry standard quarter-brick pin-out configuration
• Industry standard size: 1.45” x 2.3”
• Total height less than 0.43”, permits better airflow
and smaller card pitch
• Total weight: 42 grams (1.5 oz.), lower mass great-
ly reduces vibration and shock problems
Safety Features
• 2000V, 10 MΩinput-to-output isolation provides
input/output ground separation
• UL/cUL 60950 recognized (US & Canada), basic
insulation rating
• TUV certified to EN60950
• Meets 72/23/EEC and 93/68/EEC directives
which facilitates CE Marking in user’s end product
• Board and plastic components meet UL94V-0 flam-
mability requirements
Operational Features
• Ultra-high efficiency, 91% at 20 amp load, 88% at
40 amp load current
• Delivers up to 40 amps of output current with mini-
mal derating - no heatsink required
• Wide input voltage range: 35V – 75V, with 100V
100ms input voltage transient withstand
• Fixed frequency switching provides predictable EMI
performance
• No minimum load requirement means no preload
resistors required
Protection Features
• Input under-voltage lockout disables converter at
low input voltage conditions
• Output current limit and short circuit protection
protects converter from excessive load current or
short circuits
• Output over-voltage protection protects load from
damaging voltages
• Thermal shutdown protects converter from abnor-
mal environmental conditions
Control Features
• On/Off control referenced to input side (positive
and negative logic options are available)
• Remote sense for the output voltage compensates
for output distribution drops
• Output voltage trim permits custom voltages and
voltage margining
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 2
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
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Pin No. Name Function
1 Vin(+) Positive input voltage
2 ON/OFF TTL input to turn converter
on and off, referenced to
Vin(-), with internal pull up.
3 Vin(-) Negative input voltage
4 Vout(-) Negative output voltage
5 SENSE(-) Negative remote sense1
6 TRIM Output voltage trim2
7 SENSE(+) Positive remote sense3
8 Vout(+) Positive output voltage
Notes:
1. Pin 5 must be connected to Vout(-).
2. Leave Pin 6 open for nominal output voltage.
3. Pin 7 must be connected to Vout(+).
NOTES
1) Pins 1-3, 5-7 are 0.040” (1.02mm) diameter with
0.080” (2.03 mm) diameter standoff shoulders.
2) Pins 4 and 8 are 0.062” (1.57 mm) diameter with
0.100” (2.54 mm) diameter standoff shoulders.
3) Other pin extension lengths available. Recommended pin
length is 0.03” (0.76mm) greater than the PCB thickness.
4) All Pins: Material - Copper Alloy
Finish - Tin/Lead over Nickel plate
5) Undimensioned components are shown for visual
reference only.
6) All dimensions in inches (mm)
Tolerances: x.xx +/-0.02 in. (x.x +/-0.5mm)
x.xxx +/-0.010 in. (x.xx +/-0.25mm)
7) Weight: 1.5 oz. (42 g) typical
8) Workmanship: Meets or exceeds IPC-A-610C Class II
9)
UL/TUV standards require a clearance greater than 0.04”
(1.02mm) between input and output for Basic insulation. This
issue should be considered if any copper traces are on the top
side of the user’s board. Note that the ferrite cores are consid-
ered part of the input/primary circuit.
0.300
(7.62)
0.600
(15.24)
1.45
(36.8)
0.43
(10.9)
0.150
(3.81)
0.300
(7.62)
0.450
(11.43) 0.600
(15.24)
0.14
(3.6)
2.30
(58.4)
2.00
(50.8)
Top View
Side View
PIN CONNECTIONS
MECHANICAL
DIAGRAM
Load Board
Bottom side
Clearance
See Note 9
Lowest
Component
0.43
(10.9)
0.060+.022/-.032
(1.52+.55/-.81)
0.145
(3.68)
See Note 3
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 3
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
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Parameter
Min. Typ. Max. Units Notes & Conditions
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Non-Operating 100 V continuous
Operating 80 V continuous
Operating Transient Protection
100 V
100
ms transient; Figure 17
Isolation Voltage (input to output) 2000 V Basic level, Pollution Degree 2
Operating Temperature -40 100
°C
Storage Temperature -55 125
°C
Voltage at ON/OFF input pin -2 18 V
INPUT CHARACTERISTICS
Operating Input Voltage Range 35 48 75 V
Input Under-Voltage Lockout
Turn-On Voltage Threshold 32 33 34 V
Turn-Off Voltage Threshold 28.5 29.5 30.5 V
Lockout Hysteresis Voltage 2.5 3.5 4.5 V
Maximum Input Current 4.5 A 100% Load, 35 Vin
No-Load Input Current 55 75 mA
Disabled Input Current 1.6 3 mA
Inrush Current Transient Rating 0.01 A2s
Response to Input Transient 150 mV 1000V/ms input transient
; Figure 17
Input Reflected-Ripple Current 10 mA P-P thru 10
µH inductor; Figs. 13 & 15
Recommended Input Fuse 7 A fast blow external fuse recommended
Input Filter Component Values (C1\L\C2) 1\5\3
µF\µH\µF internal values, see Figure E
Recommended External Input Capacitance 33 47
µF see Figure 13
OUTPUT CHARACTERISTICS
Output Voltage Set Point 2.475 2.500 2.525 V
Output Voltage Regulation
Over Line +0.1 \ 2 +0.2 \ 5 %\mV
Over Load +0.1 \ 2 +0.2 \ 5 %\mV
Over Temperature +13 +38 mV
Total Output Voltage Range 2.427 2.573 V over sample, line, load, temperature & life
Output Voltage Ripple and Noise 500MHz bandwidth; Fig. 13 & 16
Peak-to-Peak 50 100 mV Full Load, see Figures 13 & 16
RMS 10 20 mV Full Load, see Figures 13 & 16
Operating Output Current Range 0 40 A
Output DC Current-Limit Inception 44 47.5 51 A Output Voltage 10% Low
Output DC Current-Limit Shutdown Voltage 1.36 V
Back-Drive Current Limit while Enabled 0.5 1.8 2.5 A Max negative current drawn from output
Back-Drive Current Limit while Disabled 0 10 50 mA Max negative current drawn from output
Maximum Output Capacitance 25,000
µF
2.5Vout at 40A Resistive Load
DYNAMIC CHARACTERISTICS
Input Voltage Ripple Rejection 71 dB 120 Hz; Fig. 20
Output Voltage during Load Current Transient
Step Change in Output Current (0.1A/µs) 80 mV 50% to 75% to 50% Iout max; Figure 11
Step Change in Output Current (1A/µs) 190 mV 50% to 75% to 50% Iout max; Figure 12
Settling Time 400 µs to within 1% Vout nom
Turn-On Transient
Turn-On Time 4 8 ms Full load, Vout=90% nom.; Figs. 9 & 10
Start-Up Inhibit Time 180 200 215 ms
-40°C to +125°C; Figure F
Output Voltage Overshoot 0 % 10,000 µF load capacitance, Iout = 0A
EFFICIENCY
100% Load 86 88 % Figures 1 - 4
50% Load 89 91 % Figures 1 - 4
TEMPERATURE LIMITS FOR POWER DERATING CURVES
Semiconductor Junction Temperature 125 °C Package rated to 150°C
Board Temperature 125 °C UL rated max operating temp 130°C
Transformer Temperature 125 °C See Figures 5 - 8 for derating curves
ISOLATION CHARACTERISTICS
Isolation Voltage 2000 V
Isolation Resistance 10 M
Ω
Isolation Capacitance 470 pF
PQ60025QTA40 ELECTRICAL CHARACTERISTICS
T
A
=25°C, airflow rate=300 LFM, V
in
=48Vdc unless otherwise noted; full operating temperature range is -40°C to +100°C ambient
temperature with appropriate power derating.
Specifications subject to change without notice.
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 4
Technical Specification
48Vin 2.5Vout 40A
Quarter
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Parameter
PMin. Typ. Max. Units Notes & Conditions
FEATURE CHARACTERISTICS
Switching Frequency 180 210 240 kHz
ON/OFF Control (Option P)
Off-State Voltage -2 0.8 V
On-State Voltage 2.4 18 V
ON/OFF Control (Option N)
Off-State Voltage 2.4 18 V
On-State Voltage -2 0.8 V
ON/OFF Control (Either Option) Figures A, B
Pull-Up Voltage Vin/6.5 9.2 V
Pull-Up Resistance 40 k
Ω
Output Voltage Trim Range -20 +10 % Measured across Pins 8 & 4; Figure C
Output Voltage Remote Sense Range +10 % Measured across Pins 8 & 4
Output Over-Voltage Protection 117 122 127 % Over full temp range; % of nominal Vout
Over-Temperature Shutdown 125 °C Average PCB Temperature
Over-Temperature Shutdown Restart Hysteresis 10 °C
RELIABILITY CHARACTERISTICS
Calculated MTBF 2.1 106Hrs. Telcordia TR-NWT-000332; 80% load,300LFM, 40oC Ta
Calculated MTBF 1.75 106Hrs. MIL-HDBK-217F; 80% load, 300LFM, 40oC Ta
Demonstrated MTBF TBD 106Hrs. Field demonstrated MTBF
Parameter
PNotes
STANDARDS COMPLIANCE
UL/cUL 60950 File # E194341, Basic insulation & pollution degree 2
EN60950 Certified by TUV
72/23/EEC
93/68/EEC
Needle Flame Test (IEC 695-2-2) test on entire assembly; board & plastic components UL94V-0 compliant
IEC 61000-4-2 ESD test, 8kV - NP, 15kV air - NP
GR-1089-CORE Section 7 - electrical safety, Section 9 - bonding/grounding
Telcordia (Bellcore) GR-513
•
An external input fuse must always be used to meet these safety requirements
Parameter
P# Units Test Conditions
QUALIFICATION TESTING
Life Test 32 95% rated Vin and load, units at derating point, 1000 hours
Vibration 5 10-55Hz sweep, 0.060” total excursion,1 min./sweep, 120 sweeps for 3 axis
Mechanical Shock 5 100g minimum, 2 drops in x and y axis, 1 drop in z axis
Temperature Cycling 10 -40°C to 100°C, unit temp. ramp 15°C/min., 500 cycles
Power/Thermal Cycling 5 Toperating = min to max, Vin = min to max, full load, 100 cycles
Design Marginality 5 Tmin-10°C to Tmax+10°C, 5°C steps, Vin = min to max, 0-105% load
Humidity 5 85°C, 85% RH, 1000 hours, 2 minutes on and 6 hours off
Solderability 15 pins MIL-STD-883, method 2003
•
Extensive characterization testing of all SynQor products and manufacturing processes is performed to ensure that we supply
robust, reliable product. Contact factory for more information about Proof of Design and Proof of Manufacturing processes.
ELECTRICAL CHARACTERISTICS (Continued)
OPTIONS
SynQor provides various options for Logic Sense, Pin Length and
Feature Set for this family of DC/DC converters. Please consult the
last page of this specification sheet for information on available
options.
PATENTS
SynQor is protected under various patents, including but not lim-
ited to U.S. Patent # 5,999,417.
STANDARDS COMPLIANCE
QUALIFICATION TESTING
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 5
Performance Curves
48Vin 2.5Vout 40A
Quarter
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85
86
87
88
89
90
91
92
93
94
95
0 100 200 300 400 500
Air Flow (LFM)
Efficiency (%)
25 C
40 C
55 C
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0 100 200 300 400 500
Air Flow (LFM)
Power Dissipation (W)
25 C
40 C
55 C
60
65
70
75
80
85
90
95
100
0 4 8 1216202428323640
Load Current (A)
Efficiency (%)
36 Vin
48 Vin
75 Vin
Figure 1: Efficiency at nominal output voltage vs. load current for min-
imum, nominal, and maximum input voltage at 25
°
C.
Figure 2: Efficiency at nominal output voltage and 60% rated power vs.
airflow rate for ambient air temperatures of 25
°
C, 40
°
C, and 55
°
C
(nominal input voltage).
0
2
4
6
8
10
12
14
0 4 8 12 16 20 24 28 32 36 40
Load Current (A)
Power Dissipation (W)
36 Vin
48 Vin
75 Vin
Figure 3: Power dissipation at nominal output voltage vs. load current
for minimum, nominal, and maximum input voltage at 25
°
C.
Figure 4: Power dissipation at nominal output voltage and 60% rated
power vs. airflow rate for ambient air temperatures of 25
°
C, 40
°
C, and
55
°
C (nominal input voltage).
0
5
10
15
20
25
30
35
40
0 2540557085
Ambient Air Temperature (oC)
Iout (A)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
0 LFM (0 m/s)
Figure 5: Maximum output power derating curves vs. ambient air tem-
perature for airflow rates of 0 LFM through 400 LFM with air flowing
across the converter from pin 3 to pin 1 (nominal input voltage).
Figure 6: Thermal plot of converter at 36 amp load current with 55
°
C
air flowing at the rate of 200 LFM. Air is flowing across the converter
from pin 3 to pin 1 (nominal input voltage).
Semiconductor junction temperature is
within 1
°
C of surface temperature
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 6
Performance Curves
48Vin 2.5Vout 40A
Quarter
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0
5
10
15
20
25
30
35
40
0 2540557085
Ambient Air Temperature (oC)
Iout (A)
400 LFM (2.0 m/s)
300 LFM (1.5 m/s)
200 LFM (1.0 m/s)
100 LFM (0.5 m/s)
0 LFM (0 m/s)
Figure 7: Maximum output power derating curves vs. ambient air tem-
perature for airflow rates of 0 LFM through 400 LFM with air flowing
lengthwise from output to input (nominal input voltage).
Figure 8: Thermal plot of converter at 35 amp load current with 55
°
C
air flowing at the rate of 200 LFM. Air is flowing lengthwise from out-
put to input (nominal input voltage).
Figure 9: Turn-on transient at full rated load (resistive load) (2 ms/div)
Ch 1: Vout (1V/div)
Ch 2: ON/OFF input (5V/div)
Figure 10: Turn-on transient at zero load current (2 ms/div).
Ch 1: Vout (1V/div)
Ch 2: ON/OFF input (5V/div)
Figure 11:Output voltage response to step-change in load current (50%-75%-
50% of Iout(max); dI/dt = 0.1A/
µ
s). Load cap: 10
µ
F, 100 m
Ω
ESR tantalum capac-
itor and 1
µ
F ceramic capacitor. Ch 1: Vout (100mV/div), Ch 2: Iout (10A/div).
Figure 12:Output voltage response to step-change in load current (50%-75%-
50% of Iout(max): dI/dt = 1A/
µ
s). Load cap: 470
µ
F, 30 m
Ω
ESR tantalum
capacitor and 1
µ
F ceramic cap. Ch 1: Vout (100mV/div), Ch 2: Iout (10A/div).
Semiconductor junction temperature is
within 1
°
C of surface temperature
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 7
Performance Curves
48Vin 2.5Vout 40A
Quarter
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Figure 14: Input Terminal Ripple Current, ic, at full rated output cur-
rent and nominal input voltage with 10
µ
H source impedance and 47
µ
F
electrolytic capacitor (100 mA/div). See Figure 13.
Figure 15: Input reflected ripple current, is, through a 10
µ
H source
inductor at nominal input voltage and rated load current (10 mA/div).
See Figure 13.
Figure 16: Output voltage ripple at nominal input voltage and rated
load current (20 mV/div). Load capacitance: 1
µ
F ceramic capacitor
and 10
µ
F tantalum capacitor. Bandwidth: 500 MHz. See Figure 13.
Figure 13: Test set-up diagram showing measurement points for Input
Terminal Ripple Current (Figure 14), Input Reflected Ripple Current
(Figure 15) and Output Voltage Ripple (Figure 16).
10
µ
H
source
impedance
DC/DC
Converter
Figure 15
Figure 14
Figure 16
1
µ
F
ceramic
capacitor
10
µ
F,
100m
Ω
ESR
tantalum
capacitor
47
µ
F,
≅1
Ω
ESR
electrolytic
capacitor
VSOURCE
iSiCVOUT
Figure 17: Output voltage response to step-change in input voltage
(50V to 100V in 40
µ
s). Load cap: 10
µ
F, 100 m
Ω
ESR tantalum capaci-
tor and 1
µ
F ceramic cap. Ch 1: Vout (100mV/div), Ch 2: Vin (20V/div).
Figure 18: Load current (20A/div) as a function of time when the con-
verter attempts to turn on into a 1 m
Ω
short circuit. Bottom trace
(2ms/div) is an expansion of the on-time portion of the top trace.
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 8
Performance Curves
48Vin 2.5Vout 40A
Quarter
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0.0001
0.001
0.01
0.1
10 100 1,000 10,000 100,000
Hz
Output Impedance (
ΩΩ
)
36 Vin
48 Vin
75 Vin
Figure 19: Magntiude of incremental output impedance (Zout =
vout/iout) for minimum, nominal, and maximum input voltage at full
rated power.
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10 100 1,000 10,000 100,000
Hz
Forward Transmission (dB)
36 Vin
48 Vin
75 Vin
Figure 20: Magnitude of incremental forward transmission (FT =
vout/vin) for minimum, nominal, and maximum input voltage at full
rated power.
-60
-50
-40
-30
-20
-10
0
10 100 1,000 10,000 100,000
Hz
Reverse Transmission (dB)
36 Vin
48 Vin
75 Vin
Figure 21: Magnitude of incremental reverse transmission (RT =
iin/iout) for minimum, nominal, and maximum input voltage at full rated
power.
0.1
1
10
100
10 100 1,000 10,000 100,000
Hz
Input Impedance (
ΩΩ
)
36 Vin
48 Vin
75 Vin
Figure 22: Magnitude of incremental input impedance (Zin = vin/iin)
for minimum, nominal, and maximum input
voltage at full rated power.
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 9
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
Brick
BASIC OPERATION AND FEATURES
The
Power
Qor series converter uses a two-stage power circuit
topology. The first stage is a buck-converter that keeps the out-
put voltage constant over variations in line, load, and temper-
ature. The second stage uses a transformer to provide the func-
tions of input/output isolation and voltage step-down to achieve
the low output voltage required.
Both the first stage and the second stage switch at a fixed fre-
quency for predictable EMI performance. Rectification of the
transformer’s output is accomplished with synchronous recti-
fiers. These devices, which are MOSFETs with a very low on-
state resistance, dissipate far less energy than Schottky diodes.
This is the primary reason that the
Power
Qor converter has such
high efficiency, even at very low output voltages and very high
output currents.
Dissipation throughout the converter is so low that it does not
require a heatsink for operation. Since a heatsink is not
required, the
Power
Qor converter does not need a metal base-
plate or potting material to help conduct the dissipated energy
to the heatsink. The
Power
Qor converter can thus be built more
simply and reliably using high yield surface mount techniques
on a PCB substrate.
The
Power
Qor series of half-brick and quarter-brick converters
uses the industry standard footprint and pin-out configuration.
CONTROL FEATURES
REMOTE ON/OFF (Pin 2): The ON/OFF input, Pin 2, per-
mits the user to control when the converter is
on
or
off
. This
input is referenced to the return terminal of the input bus,
Vin(-). There are two versions of the converter that differ by the
sense of the logic used for the ON/OFF input.
In the positive logic version, the ON/OFF input is active high
(meaning that a high turns the converter
on
). In the negative
logic version, the ON/OFF signal is active low (meaning that a
low turns the converter
on
). Figure A details five possible cir-
cuits for driving the ON/OFF pin. Figure B is a detailed look of
the internal ON/OFF circuitry.
REMOTE SENSE(+) (Pins 7 and 5): The SENSE(+) inputs
correct for voltage drops along the conductors that connect the
converter’s output pins to the load.
Pin 7 should be connected to Vout(+) and Pin 5 should be con-
nected to Vout(-) at the point on the board where regulation is
desired. A remote connection at the load can adjust for a volt-
age drop only as large as that specified in this datasheet, that
is
[Vout(+) - Vout(-)]– [SENSE(+) - SENSE(-)]<
Sense Range % x Vout
Pins 7 and 5 must be connected for proper regulation of the
output voltage. If these connections are not made, the convert-
er will deliver an output voltage that is slightly lower than its
specified value.
Open Collector Enable Circuit
Figure A: Various circuits for driving the ON/OFF pin. Figure B: Internal ON/OFF pin circuitry
Remote Enable Circuit
Direct Logic Drive
Negative Logic
(Permanently Enabled)
Positive Logic
(Permanently Enabled)
ON/OFF
Vin(_)
ON/OFF
ON/OFF
Vin(_)
ON/OFF
5V
TTL/
CMOS
Vin(_)
ON/OFF
Vin(_)
Vin(_)
TTL
5V
50k
274k
Vin(+)
ON/OFF
Vin(_)
50k
100pF
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 10
Technical Specification
48Vin 2.5Vout 40A
Quarter
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Note: the output over-voltage protection circuit senses the volt-
age across the output (pins 8 and 4) to determine when it
should trigger, not the voltage across the converter’s sense
leads (pins 7 and 5). Therefore, the resistive drop on the board
should be small enough so that output OVP does not trigger,
even during load transients.
OUTPUT VOLTAGE TRIM (Pin 6): The TRIM input permits
the user to adjust the output voltage across the sense leads up
or down according to the trim range specifications.
To decrease the output voltage, the user should connect a resis-
tor between Pin 6 and Pin 5 (SENSE(-) input). For a desired
decrease of the nominal output voltage, the value of the resis-
tor should be
Rtrim-down =
(
511
)
- 10.22 (kΩ)
∆%
where
∆% =
(
Vnominal – Vdesired
)
x100%
Vnominal
To increase the output voltage, the user should connect a resis-
tor between Pin 6 and Pin 7 (SENSE(+) input). For a desired
increase of the nominal output voltage, the value of the resistor
should be
Figure C graphs the relationship between the trim resistor value
and Rtrim-up and Rtrim-down, showing the total range the out-
put voltage can be trimmed up or down.
Figure C: Trim Graph for 2.5Vout module
Note: the TRIM feature does not affect the voltage at which the
output over-voltage protection circuit is triggered. Trimming the
output voltage too high may cause the over-voltage protection
circuit to engage, particularly during transients.
It is not necessary for the user to add capacitance at the Trim
pin. The node is internally bypassed to eliminate noise.
Total DC Variation of Vout: For the converter to meet its
full specifications, the maximum variation of the DC value of
Vout, due to both trimming and remote load voltage drops,
should not be greater than that specified for the output voltage
trim range.
PROTECTION FEATURES
Input Under-Voltage Lockout: The converter is designed
to turn off when the input voltage is too low, helping avoid an
input system instability problem, described in more detail in the
application note titled “Input System Instability”. The lockout cir-
cuitry is a comparator with DC hysteresis. When the input volt-
age is rising, it must exceed the typical Turn-On Voltage
Threshold value (listed on the specification page) before the
converter will turn on. Once the converter is on, the input volt-
age must fall below the typical Turn-Off Voltage Threshold value
before the converter will turn off.
Output Current Limit: The maximum current limit remains
constant as the output voltage drops. However, once the imped-
ance of the short across the output is small enough to make the
output voltage drop below the specified Output DC Current-
Limit Shutdown Voltage, the converter turns off.
The converter then enters a “hiccup mode” where it repeatedly
turns on and off at a 5 Hz (nominal) frequency with a 5% duty
cycle until the short circuit condition is removed. This prevents
excessive heating of the converter or the load board.
Output Over-Voltage Limit: If the voltage across the output
pins exceeds the Output Over-Voltage Protection threshold, the
converter will immediately stop switching. This prevents dam-
age to the load circuit due to 1) excessive series resistance in
output current path from converter output pins to sense point, 2)
a release of a short-circuit condition, or 3) a release of a cur-
rent limit condition. Load capacitance determines exactly how
high the output voltage will rise in response to these conditions.
After 200 ms the converter will automatically restart.
Over-Temperature Shutdown: A temperature sensor on
the converter senses the average temperature of the module.
The thermal shutdown circuit is designed to turn the converter
off when the temperature at the sensed location reaches the
Rtrim-up
(k
Ω)
)
where
VOUT = Nominal Output Voltage
= (
_511 _10.22
5.11VOUT(100+
∆%)
1.225∆%∆%
10
100
1,000
10,000
0 2 4 6 8 10 12 14 16 18 20
Trim Resistance (kOhms)
% increase Vout % decrease Vout
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 11
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
Brick
Over-Temperature Shutdown value. It will allow the converter to
turn on again when the temperature of the sensed location falls
by the amount of the Over-Temperature Shutdown Restart
Hysteresis value.
APPLICATION CONSIDERATIONS
Input System Instability: This
condition can occur
because any DC/DC converter appears incrementally as a
negative resistance load. A detailed application note titled
“Input System Instability” is available on the SynQor web site
(www.synqor.com) which provides an understanding of why
this instability arises, and shows the preferred solution for cor-
recting it.
Application Circuits: Figure D below provides a typical cir-
cuit diagram which details the input filtering and voltage trim-
ming.
Input Filtering and External Capacitance: Figure E
below provides a diagram showing the internal input filter com-
ponents. This filter dramatically reduces input terminal ripple
current, which otherwise could exceed the rating of an external
electrolytic input capacitor. The recommended external input
capacitance is specified in the “Input Characterisitcs” section.
More detailed information is available in the application note
titled “EMI Characteristics” on the SynQor website.
Vin External
Input
Filter
Trim
Vin(+)
Iload
Cload
L
Vout(+)
Rtrim-up
or
Rtrim-down
Vsense(+)
ON/OFF
Vin(_)
Vin(+)
Vin(_)
Vout(_)
Vsense(_)
Electrolytic
Capacitor
33µF
ESR
≅
1
Ω
Figure D: Typical application circuit (negative logic unit, permanently enabled).
Figure E: Internal Input Filter Diagram (component values listed on page 3).
C1C2
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 12
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
Brick
Startup Inhibit Period: The Startup Inhibit Period ensures
that the converter will remain off for at least 200ms when it is
shut down for any reason. When an output short is present,
this generates a 5Hz "hiccup mode," which prevents the con-
verter from overheating. In all, there are seven ways that the
converter can be shut down, initiating a Startup Inhibit Period:
• Input Under-Voltage Lockout
• Input Over-Voltage Shutdown (not present in Quarter-brick)
• Output Over-Voltage Protection
• Over Temperature Shutdown
• Current Limit
• Short Circuit Protection
• Turned off by the ON/OFF input
Figure F shows three turn-on scenarios, where a Startup Inhibit
Period is initiated at t0, t1, and t2:
Before time t0, when the input voltage is below the UVL thresh-
old, the unit is disabled by the Input Under-Voltage Lockout fea-
ture. When the input voltage rises above the UVL threshold, the
Input Under-Voltage Lockout is released, and a Startup Inhibit
Period is initiated. At the end of this delay, the ON/OFF pin is
evaluated, and since it is active, the unit turns on.
At time t1, the unit is disabled by the ON/OFF pin, and it can-
not be enabled again until the Startup Inhibit Period has
elapsed.
When the ON/OFF pin goes high after t2, the Startup Inhibit
Period has elapsed, and the output turns on within the typical
Turn-On Time.
Under-Voltage
Lockout Turn-On
Threshold
ON/OFF
(pos logic)
Figure F: Startup Inhibit Period (turn-on time not to scale)
Vout
Vin
200ms 200ms
200ms
(typical start-up
inhibit period)
t0t1t2t
4ms (typical
turn on time)
ON ON ON
OFF OFF
Product # PQ60025QTA40 Phone 1-888-567-9596 Doc.# 005-2QT625C Rev. B 3/6/03 Page 13
Technical Specification
48Vin 2.5Vout 40A
Quarter
Quarter
Brick
Brick
PART NUMBERING SYSTEM
The part numbering system for SynQor’s
Power
Qor DC/DC
converters follows the format shown in the example below.
The first 12 characters comprise the base part number and
the last 3 characters indicate available options. Although
there are no default values for enable logic and pin length,
the most common options are negative logic and 0.145”
pins. These part numbers are more likely to be readily avail-
able in stock for evaluation and prototype quantities.
Application Notes
A variety of application notes and technical white papers
can be downloaded in pdf format at www.synqor.com.
ORDERING INFORMATION
The tables below show the valid model numbers and order-
ing options for converters in this product family. When
ordering SynQor converters, please ensure that you use the
complete 15 character part number consisting of the 12
character base part number and the additional 3 characters
for options.
The following option choices must be included in place of
the
x y z
spaces in the model numbers listed above.
Warranty
SynQor offers a three (3) year limited warranty. Complete warranty
information is listed on our web site or is available upon request from
SynQor.
Information furnished by SynQor is believed to be accurate and reliable.
However, no responsibility is assumed by SynQor for its use, nor for any
infringements of patents or other rights of third parties which may result
from its use. No license is granted by implication or otherwise under any
patent or patent rights of SynQor.
Contact SynQor for further information:
Phone: 508-485-8434
Toll Free: 888-567-9596
Fax: 508-485-8414
E-mail: sales@synqor.com
Web: www.synqor.com
Address: 188 Central Street
Hudson, MA 01749
Output Max Output
Voltage Current
PQ60010QTA40xyz 35 - 75 V 1.0 V 40 A
PQ60012QTA40xyz 35 - 75 V 1.2 V 40 A
PQ60015QTA40xyz 35 - 75 V 1.5 V 40 A
PQ60018QTA40xyz 35 - 75 V 1.8 V 40 A
PQ60025QTA40xyz 35 - 75 V 2.5 V 40 A
PQ60033QTA35xyz 35 - 75 V 3.3 V 35 A
Model Number
Input Voltage
Enable Pin Feature
Logic Length Set
P - Positive
N - Negative
K - 0.110"
N - 0.145"
R - 0.180"
Y - 0.250"
S - Standard
Options Description: x y z
PQ 48 033 H T A 50 N K S
Product Family
Package Size
Performance Level
Thermal Design
Output Current
Options (see
Ordering Information)
Input Voltage
Output Voltage
