Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 1
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
The PQ48120QNA08 PowerQor™ 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.
High Efficiency, No Heatsink, Isolated DC/DC Converter
PQ48120QNA08 Module
Mechanical Features
• Industry standard pin-out configuration (pin for pin
compatible with Lucent QHW series)
• Industry standard size: 1.45” x 2.3”
• Total height less than 0.40”, permits better airflow
and smaller card pitch
• Total weight: 34 grams (1.2 oz.), lower mass great-
ly reduces vibration and shock problems
Safety Features
• 2000V, 10 MΩinput-to-output isolation provides
input/output ground separation
• UL 1950 recognized (US & Canada), basic insula-
tion rating
• TUV certified to EN60950
Safety Features (cont.)
• Meets 72/23/EEC and 93/68/EEC directives
which facilitates CE Marking in user’s end product
• Board and plastic components meet 94V-0 flamma-
bility requirements
Operational Features
• Ultra-high efficiency, 88% at full rated load current
• Delivers up to 100 Watts of output power with mini-
mal derating - no heatsink required
• Wide input voltage range: 35V – 75V meets or
exceeds all 48V bus standards
• 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: +10%/-20%, permits custom
voltages and voltage margining
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 2
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
Shown Actual Size
Pin No. Name Function
1 Vin(+) Positive input voltage (35V - 75V)
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(-) at load.
2. Leave Pin 6 open for nominal output voltage.
3. Pin 7 must be connected to Vout(+) at load.
1) All dimensions in inches (mm)
2) Pins 1-3, 5-7 are 0.040” (1.02mm) dia. with
0.080” (2.03mm) dia. standoff shoulders.
3) Pins 4 and 8 are 0.062” (1.57 mm) dia. with 0.100”
(2.54mm) dia. standoff shoulders.
4) All pins are Brass with Tin/Lead plating over Nickel
5) Tolerances: x.xx in. +/-0.02 in. (0.5mm)
x.xxx in. +/-0.010 in. (0.25mm)
6)
Weight: 1.20 oz. (34 g)
7) Workmanship: Meets or exceeds IPC-A-610B Class II
OPTIONS
The PQ48120QNA08 comes in two versions that differ by
the sense of the logic used for the ON/OFF control signal.
The PQ48120QNA08P version uses positive logic; mean-
ing that the converter is on when the ON/OFF signal (Pin
2) is high. The PQ48120QNA08N version uses negative
logic; the converter is on when the ON/OFF signal is low.
Logic input is TTL compatible with an internal pull up.
SAFETY
The PQ48120QNA08 series of converters are UL 1950
recognized (US & Canada) with basic insulation rating
and TUV certified to EN60950 requirements.
The converters also meet 72/23/EEC and 93/68/EEC
directives as well as 94V-0 flammability requirements for
board and plastic components.
An external input fuse must always be used to meet these
safety requirements.
0.40
(10.2)
0.300
(7.62)
1.45
(36.8)
0.43
(10.8)
0.14
(3.6)
2.30
(58.4)
2.00
(50.8)
0.150
(3.81)
0.300
(7.62)
0.450
(11.43) 0.600
(15.24)
0.600
(15.24)
0.110 *
(2.79)
Top View
Side View
* Other pin lengths available
ABSOLUTE MAXIMUM RATINGS
Input Voltage:
Non-Operating: 100V continuous
Operating: 80V continuous
100V 10
µ
s transients,1% duty cycyle
Input/Output Isolation Voltage: 2000V
Storage Temperature: -55°C to +125°C
Operating Temperature: -40°C to +115°C
Voltage at ON/OFF input pin: +18V / -2V
Patents: SynQor is protected under various patents,
including but not limited to U.S. Patent # 5,999,417.
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 3
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
PARAMETER NOTES and CONDITIONS PQ48120QNA08
Min. Typ. Max. Units
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 100% Load, 35Vin 3.5 A
No-Load Input Current 80 120 mA
Off Converter Input Current 1.6 3 mA
Inrush Current Transient Rating .01 A2s
Input Reflected-Ripple Current P-P thru 10
µH inductor
; Figures 13 & 15 6 mA
OUTPUT CHARACTERISTICS
Output Voltage Set Point 11.82 12.00 12.18 V
Output Voltage Regulation
Over Load +5+24 mV
Over Line +5+24 mV
Over Temperature +90 +240 mV
Total Output Voltage Range over sample load, line and temperature 11.58 12.42 V
Output Voltage Ripple and Noise 20MHz bandwidth; Figures 13 & 16
Peak-to-Peak Full Load, 1
µF ceramic, 10µF tantalum
75 150 mV
RMS Full Load, 1
µF ceramic, 10µF tantalum
15 30 mV
Operating Output Current Range 0 8.33 A
Output DC Current-Limit Inception Output Voltage 10% Low; Figure 17 9 9.6 11 A
Short-Circuit Protection (redundant shutdown) 16 18 20 A
DYNAMIC CHARACTERISTICS
Input Voltage Ripple Rejection 120 Hz; Figure 20 55 dB
Output Voltage Current Transient 100µF load cap, 5A/µs; Figure 12
Positive Step Change in Output Current 50% Io to 75% Io 500 mV
Negative Step Change in Output Current 75% Io to 50% Io 500 mV
Settling Time to 1% 800 µs
Turn-On Transient
Turn-On Time Figures 9 & 10 4 8 12 ms
Start-Up Inhibit Period
-40°C to +125°C; Figure F 180 200 215 ms
Maximum Output Capacitance Full load; 5% overshoot of Vout at startup 2,000 µF
EFFICIENCY
100% Load Figure 1 88.0 %
50% Load 88.4 %
TEMPERATURE LIMITS FOR POWER DERATING CURVES
Semiconductor Junction Temperature Package rated to 150°C 125 °C
Board Temperature Board rated to 165°C 125 °C
Transformer Temperature Figures 5 & 7 125 °C
ISOLATION CHARACTERISTICS
Isolation Voltage 2000 V
Isolation Resistance 10 M
Ω
Isolation Capacitance 470 pF
FEATURE CHARACTERISTICS
Switching Frequency 195 215 235 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)
Pull-Up Voltage See circuit diagram; Figure E Vin/6.5 9.2 V
Pull-Up Resistance Pull up to Vin/6 40 k
Ω
Output Voltage Trim Range Across Pins 8 & 4; Figures B & C -20 +10 %
Output Voltage Remote Sense Range Across Pins 7 & 5 +10 %
Output Over-Voltage Protection Over full temp range; % of nominal Vout 117 122 127 %
Over-Temperature Shutdown Average PCB Temperature 125 °C
PQ48120QNA08 ELECTRICAL CHARACTERISTICS
(T
A
=25°C, airflow rate=300 LFM, V
in
=48Vdc unless otherwise noted; full operating temperature range is -40°C to +115°C ambient
temperature with appropriate power derating.)
Specifications subject to change without notice.
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 4
Performance Curves
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
60
65
70
75
80
85
90
95
0.0 0.8 1.7 2.5 3.3 4.2 5.0 5.8 6.7 7.5 8.3
Load Current (A)
Efficiency (%)
36 Vin
48 Vin
75 Vin
Figure 1: Efficiency vs. load current for minimum, nominal, and
maximum input voltage at 25
°
C.
82
83
84
85
86
87
88
89
90
0 100 200 300 400 500
Air Flow (LFM)
Efficiency (%)
25 C
40 C
55 C
Figure 2: Efficiency at 60% rated power vs. airflow rate for ambient
air temperatures of 25
°
C, 40
°
C, and 55
°
C and nominal input voltage.
0
2
4
6
8
10
12
14
16
0.0 0.8 1.7 2.5 3.3 4.2 5.0 5.8 6.7 7.5 8.3
Load Current (A)
Power Dissipation (W)
36 Vin
48 Vin
75 Vin
Figure 3: Power dissipation vs. load current for minimum, nominal,
and maximum input voltage at 25
°
C.
5.0
5.5
6.0
6.5
7.0
7.5
8.0
8.5
9.0
9.5
10.0
0 100 200 300 400 500
Air Flow (LFM)
Power Dissipation (W)
25 C
40 C
55 C
Figure 4: Power dissipation at 60% rated power vs. airflow rate for
ambient air temperatures of 25
°
C, 40
°
C, and 55
°
C and nominal input
voltage.
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
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 1 to pin 3 (nominal input voltage).
Figure 6: Thermal plot of converter at 6.6 amp load current with 55
°
C
air flowing at the rate of 200 LFM. Air is flowing across the converter
sideways from pin 1 to pin 3 (nominal input voltage).
Vin = 48V
Semiconductor junction temperature is
within 2
°
C of surface temperature
Vin = 48V
Vin = 48V
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 5
Performance Curves
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
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 input to output (nominal input voltage).
Figure 8: Thermal plot of converter at 6.4 amp load current with 55
°
C
air flowing at the rate of 200 LFM. Air is flowing across the converter
in the long direction from input to output (nominal input voltage).
Figure 9: Turn-on transient at full rated load current (resistive load) (2
ms/div) Top Trace: Vout; 5V/div
Bottom Trace: ON/OFF input; 5V/div
Figure 10: Turn-on transient at zero load current (2 ms/div).
Top Trace: Vout; 5V/div
Bottom Trace: ON/OFF input; 5V/div
Figure 11: Output voltage response to step-change in load current (50%-75%-50%
of Imax; dI/dt = 0.1A/
µ
s). Load cap: 10
µ
F, 100 m
Ω
ESR tantalum capacitor and
1
µ
F ceramic capacitor. Top trace: Vout (500mV/div), Bottom trace: Iout (2A/div).
Figure 12:Output voltage response to step-change in load current (50%-75%-50%
of Imax: dI/dt = 5A/
µ
s). Load cap: 100
µ
F, 30 m
Ω
ESR tantalum capacitor and 1
µ
F
ceramic capacitor. Top trace: Vout (500mV/div), Bottom trace: Iout (2A/div).
Vin = 48V
Semiconductor junction temperature is
within 2
°
C of surface temperature
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 6
Performance Curves
48Vin 12Vout 8.3A
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 (50 mV/div). Load capacitance: 1
µ
F ceramic capacitor
and 10
µ
F tantalum capacitor. Bandwidth: 20 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).
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
0
1
2
3
4
5
6
7
8
9
10
11
Load Current (A)
Output Voltage (V)
36 V
48 V
75 V
Figure 17: Output voltage vs. load current showing typical current limit
curves and converter shutdown points.
Figure 18: Load current (5A/div) as a function of time when the con-
verter attempts to turn on into a 10 m
Ω
short circuit. Top trace is an
expansion of the on-time portion of the bottom trace.
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
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 7
Performance Curves
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
0.001
0.01
0.1
1
10 100 1,000 10,000 100,000
Hz
Output Impedance ( )
36 Vin
48 Vin
75 Vin
Figure 19: Output impedance (Zout = Vout/Iout) for minimum, nomi-
nal, and maximum input voltage at full rated power.
-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: Forward Transmission (FT = Vout/Vin) for minimum, nomi-
nal, and maximum input voltage at full rated power.
-60
-50
-40
-30
-20
-10
0
10
10 100 1,000 10,000 100,000
Hz
Reverse Transmission (dB)
36 Vin
48 Vin
75 Vin
Figure 21: Reverse Transmission (RT = Iin/Iout) for minimum, nomi-
nal, and maximum input voltage at full rated power.
0.1
1
10
100
10 100 1,000 10,000 100,000
Hz
Input Impedance ( )
36 Vin
48 Vin
75 Vin
Figure 22: Input impedance (Zin = Vin/Iin) for minimum, nominal, and
maximum input
voltage at full rated power.
BASIC OPERATION AND
FEATURES
The
Power
Qor series converter uses a two-stage power cir-
cuit topology. The first stage is a buck-converter that keeps
the output voltage constant over variations in line, load, and
temperature. The second stage uses a transformer to provide
the functions 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
frequency for predictable EMI performance. Rectification of
the transformer’s output is accomplished with synchronous
rectifiers. These devices, which are MOSFETs with a very
low on-state resistance, dissipate far less energy than
Schottky diodes used in conventional dc/dc converters. 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 the
Power
Qor converter requires no heatsink to deliver
a greater level of power than can be delivered by a con-
ventional, Schottky-diode-based dc/dc converter with a
0.5” high heatsink. At equivalent ambient air temperature,
airflow rate, and output power level, the hottest semicon-
ductor junction temperature and the hottest PCB temperature
within the
Power
Qor converter are cooler than those found
in conventional dc/dc converters with a 0.5” high heatsink
attached.
Since a heatsink is not required, the
Power
Qor converter
does not need a metal baseplate or potting material to help
conduct the dissipated energy to the heatsink. The
Power
Qor converter can thus be built more simply using
high yield surface mount techniques on a PCB substrate.
Unlike conventional dc/dc converters, which have critical
thermal connections between the power components and the
baseplate, and between the baseplate and the heatsink, the
Power
Qor converter has no explicit, failure-prone thermal
connections.
Compared to a conventional Schottky-diode-based dc/dc
converter with a 0.5” high heatsink, the
Power
Qor convert-
er is more efficient and therefore it dissipates less than half
the energy. Additionally, because the
Power
Qor converter is
thinner (0.4” vs. 1.0”), the board-to-board pitch in a rack
can be much smaller, and cooling airflow is less impeded by
the converter. Because the
Power
Qor converter is much
lighter, vibration and shock-induced problems are greatly
reduced. Moreover, due to the lack of failure-prone explicit
thermal connections and the lack of potting material the
Power
Qor converter is more reliable than conventional
dc/dc converters.
The
Power
Qor series converter uses the industry standard
pin-out configuration used by other vendors of comparably
sized and rated dc/dc converters. The unit is pin for pin
compatible with the Lucent QW series.
The
Power
Qor converter has many standard control and
protection features. All shutdown features are non-latching,
meaning that the converter shuts off for 200ms before
restarting. (see
Figure F
)
• An ON/OFF input permits the user to control when the
converter is
on
and
off
in order to properly sequence dif-
ferent power supplies and to reduce power consumption
during a standby condition.
•Remote sense inputs permit the user to maintain an
accurate voltage at the load despite distribution voltage
drops between the converter’s output and the load.
• An output voltage trim input permits the user to trim
the output voltage up or down to achieve a custom volt-
age level or to do voltage margining.
• An input under-voltage lockout avoids input system
instability problems while the input voltage is rising.
•The output current limit protects both the converter
and the board on which it is mounted against a short cir-
cuit condition.
• An output over-voltage limit circuit shuts the unit
down if the output voltage at the output pins gets too
high.
• A sensor located in a central spot of the PCB provides a
PCB temperature limit. If, due to an abnormal con-
dition, this spot gets too hot, the converter will turn off.
Once the converter has cooled, it will automatically turn
on again without the need to recycle the input power.
CONTROL PIN DESCRIPTIONS
Pin 2 (ON/OFF): The ON/OFF input, Pin 2, permits the
user to control when the converter is
on
or
off
. This input is
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 8
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
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referenced to the return terminal of the 48V input bus. There
are two versions of the
Power
Qor series converter that differ
by the sense of the logic used for the ON/OFF input. In the
PQxxyyyQNAzzPxx version, the ON/OFF input is active
high (meaning that a high turns the converter
on
). In the
PQxxyyyQNAzzNxx version, the ON/OFF signal is active
low (meaning that a low turns the converter
on
). Figure A
details five possible circuits for driving the ON/OFF pin.
Pins 7 and 5 (SENSE(+)): The SENSE(+) inputs correct
for voltage drops along the conductors that connect the con-
verter’s output pins to the load.
Pin 7 should be connected to Vout(+) and Pin 5 should be
connected to Vout(-) at the point on the board where regu-
lation is desired. That is,
[Vout(+) - Vout(-)]– [SENSE(+) - SENSE (-)] <10%Vout
Pins 7 and 5 must be connected for proper regulation of the
output voltage. However, if these connections are not made,
nothing catastrophic will happen to the converter under nor-
mal operating conditions—the converter will simply deliver
an output voltage that is slightly higher than its specified
value.
Note: the output over-voltage protection circuit senses the
voltage across the output (pins 8 and 4) to determine when
it should trigger, not the voltage across the converter’s sense
pins (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.
Pin 6 (TRIM): The TRIM input permits the user to adjust the
output voltage across the sense leads up or down. To lower
the output voltage, the user should connect a resistor
between Pin 6 and Pin 5, which is the SENSE(-) input. To
raise the output voltage, the user should connect a resistor
between Pin 6 and Pin 7, which is the SENSE(+) input.
A resistor connected between Pin 6 and Pin 5 will decrease
the output voltage. For a desired decrease of ∆percent of
the nominal output voltage, the value of this resistor should
be
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 9
Technical Specification
48Vin 12Vout 8.3A
Quarter
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Open Collector Enable Circuit
Figure A: Various circuits for driving the ON/OFF pin.
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(_)
Rtrim-down =
(
511
)
- 10.22
∆%
(k
Ω)
∆=
(
VNOM – VDES
)
x100%
VNOM
where
VNOM = Nominal Voltage
VDES = Desired Voltage
and
Figure B graphs this relationship between Rtrim-down and ∆.
The output voltage can be trimmed down as much as 20%.
Figure B: Trim Down Graph for 12Vout
A resistor connected between Pin 6 and Pin 7 will increase
the output voltage. For a desired increase of ∆percent of the
nominal output voltage, the value of this resistor should be
Figure C graphs this relationship between Rtrim-up and ∆.
The output voltage can be trimmed up as much as 10%.
Figure C: Trim Up Graph for 12Vout
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 tran-
sients.
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 +10%/-20%
PROTECTION FEATURES
Input Under-Voltage Lockout: The converter is
designed to turn off when the input voltage is too low, help-
ing avoid an input system instability problem, described in
more detail below. The lockout circuitry is a comparator with
dc hysteresis. When the input voltage is rising, it must
exceed a typical value of 33V before the converter will turn
on. Once the converter is on, the input voltage must fall
below a typical value of 29.5V before the converter will turn
off.
Output Current Limit: The current limit does not change
appreciably as the output voltage drops. However, once the
impedance of the short across the output is small enough to
make the output voltage drop below approximately 60% of
its nominal value, the converter turns off.
The converter then enters a 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 pre-
vents excessive heating of the converter or the load board
(see Figure 18).
Output Over-Voltage Limit: If the voltage across the
output pins exceeds the O.V. threshold, the converter will
immediately stop switching. This prevents damage to the
load circuit due to 1) a sudden unloading of the converter,
2) a release of a short-circuit condition, or 3) a release of a
current 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.
Thermal Shutdown: The
Power
Qor series has a temper-
ature sensor located such that it senses the average temper-
ature of the converter. The thermal shutdown circuit is
designed to turn the converter off when the temperature at
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 10
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
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10
100
1,000
10,000
0 2 4 6 8 10 12 14 16 18 20
% Decrease in Output Voltage
Trim Resistance (kOhms)
100
1,000
10,000
100,000
012345678910
% Increase in Output Voltage
Trim Resistance (kOhms)
Rtrim-up
(k
Ω)
)
where
VOUT = Nominal Output Voltage
= (
_511 _10.22
5.11VOUT(100+
∆%)
1.225∆%∆%
the sensed location reaches 115°C. It will allow the con-
verter to turn on again when the temperature of the sensed
location falls below 110°C.
APPLICATION CONSIDERATIONS
Input System Instability: This
condition can occur
because a 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 solu-
tion for correcting it.
Application Circuits:
Figure D
below provides a typical
circuit diagram which is useful when using input filtering
and voltage trimming.
Figure E
is a detailed look of the inter-
nal ON/OFF circuitry that is shown in
Figure A
.
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 11
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
Figure E: Internal ON/OFF pin circuitry
TTL
5V
50k
274k
Vin(+)
ON/OFF
Vin(_)
35V < Vin < 75V
Input Filtering
Trim
Vin(+)
Iload
Cload
Vout(+)
Rtrim-up
or
Rtrim-down
Vsense(+)
ON/OFF
Vin(_)Vout(_)
Vsense(_)
Electrolytic
Capacitor
33µF
ESR
≅
1
Ω
Figure D: Typical application circuit (negative logic unit, permanently enabled).
50k
100pF
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 converter from over-
heating. 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 34V (typ.),
the unit is disabled by the Input Under-Voltage Lockout fea-
ture. When the input voltage rises above 34V, 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
cannot 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 4ms
(typ.) "Turn On Time."
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 12
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
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)
t0t1t2
t
4ms (typical
turn on time)
ON ON ONOFF OFF
PART NUMBERING SYSTEM
The part numbering system for SynQor’s
Power
Qor DC/DC
converters has the following format:
Example part #: PPQQ4488003333QQNNAA2255NNNNSS
This part number indicates a
Power
Qor converter with
48Vin, 3.3Vout, quarter-brick size, normal performance
level, open air design, 25 amps output current, negative
logic, 0.145” pins, and the standard feature set.
When ordering SynQor converters, please ensure that you
use the complete 15 character part number.
Product # PQ48120QNA08 Phone 1-888-567-9596 Doc.# 005-2QN412D_C 9/04/01 Page 13
Technical Specification
48Vin 12Vout 8.3A
Quarter
Quarter
Brick
Brick
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: 978-567-9596
Toll Free: 888-567-9596
Fax: 978-567-9599
E-mail: sales@synqor.com
Web: www.synqor.com
Address: 188 Central Street
Hudson, MA 01749
Output Performance Thermal "Rated" Pos./Neg.
Product Family Input Voltage Voltage Package Size Series Design Output Current Logic Pin Length Features
PQ 48 033 Q N A 25 N N S
015 - 1.5V
018 - 1.8V
020 - 2.0V
025 - 2.5V
033 - 3.3V
050 - 5.0V 20 - 20 Amps
060 - 6.0V 17 - 16.67 Amps
120 - 12V 08 - 8.33 Amps
150 - 15V 07 - 6.67 Amps
S - Standard
Quarter-Brick Product Family and Part Numbering Scheme
Base Part Number
Options
PQ - PowerQor
48 - (35v-75v)
Q - Quarter Brick
N - Normal
A - Open Frame
B - Baseplate
25 - 25 Amps
P - Positive
N - Negative
K - 0.110"
N - 0.145"
R - 0.180"
Y - 0.250"
