switching frequency dc/dc converter that uses synchro-
nous 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. The BusQor
series provides an isolated step down voltage from 48V
to a 9.6V intermediate bus with no regulation in a stan-
dard “quarter-brick” module. BusQor converters are
ideal for creating the mid-bus voltage required to drive
point-of-load (non-isolated) converters in intermediate
bus architectures.
Bus
Conver ter
BQ55090QTA27 Module
Operational Features
• Ultra-high efficiency, 96% at full rated load current
• Delivers up to 36 amps (240 Watts) of output current
(power) with minimal derating - no heatsink required
• Input voltage range: 36V – 55V provides 7.2-11V
bus for distributed power architectures
• Fixed frequency switching provides predictable EMI
performance
Protection Features
• Input under-voltage lockout and over-voltage
shutdown protects against abnormal input voltages
• Latching output current limit and short circuit pro-
tection
• Latching thermal shutdown
Mechanical Features
• Industry standard quarter-brick bus converter pin-out
• Industry standard size: 1.45” x 2.3”
(36.8x58.4mm)
• Total height only 0.445”
(11.3mm),
permits better
airflow and smaller card pitch
• Total weight: 1.5 oz.
(42 grams)
• Flanged pins designed to permit surface mount sol-
dering (avoid wave solder) using FPiP technique
Safety Features
• 2000V, 30 MΩ input-to-output isolation
• UL/cUL 60950 recognized (US & Canada), basic
insulation rating
• TUV certified to EN60950
• Meets 72/23/EEC and 93/68/EEC directives
• Meets UL94V-0 flammability requirements
Control Features
• On/Off control referenced to input side (positive
or negative logic options)
• Inherent current share (by droop method) for high
current and parallel applications
Product # BQ55090QTA27
Phone 1-888-567-9596
* Final datasheet pending ECO review and signature.
Doc.# 005-2BQ559J Rev. B
10/1/04
Page 1
Technical Specification
Quarter
Brick
MECHANICAL
DIAGRAM
2.30
(58.4)
48Vin 9.6Vout 27A
0.14
(3.6)
2.00
(50.8)
0.43
(10.8)
Top View
0.600
(15.24)
1.45
(36.8)
0.600
(15.24)
0.300
(7.62)
Side View
0.145
(3.68)
See Note 3
Load Board
Lowest
Component
Flanged Pin
See Note 10
0.445 + 0.022
(11.3 + 0.55)
0.056+/-0.034
(1.42+/-0.86)
Bottom side
Clearance
See Note 9
NOTES
1) Pins 1-3 are 0.040” (1.02mm) diameter with
0.080” (2.03 mm) diameter standoff shoulders.
2) Pins 4 and 5 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.
PIN DESIGNATIONS
Pin No. Name
1
2
3
4
5
Vin(+)
ON/OFF
Vin(-)
Vout(-)
Vout(+)
Function
Input Positive (36V - 55V)
Logic control input to turn
converter on and off.
Input Negative
Output Negative
Output Positive
10) The flanged pins are designed to permit surface mount
soldeing (avoiding the wave soldering process) through
the use of the flanged pin-in-paste technique.
Product # BQ55090QTA27
Phone 1-888-567-9596
Doc.# 005-2BQ559J Rev. B
10/1/04
Page 2
Technical Specification
Quarter
Brick
BQ55090QTA27 ELECTRICAL CHARACTERISTICS
Parameter
ABSOLUTE MAXIMUM RATINGS
48Vin 9.6Vout 27A
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.
Min.
Typ.
Max.
60
55
2000
100
125
18
48
55
34.5
33.5
2
58.5
57
7.0
7
120
1\6.6
47
9.6
40\3.8
5.2\500
2\200
6.55
35
12
48
33
5
+20
10
23
200
100
3
0
95.8
96.5
125
125
125
2000
30
250
5
11.0
50
36
Units
V
V
V
°C
°C
V
V
V
V
V
V
V
A
A
mA
A
2
s
mA
mA
A
µH\µF
µF
V
%\V
%\mV
%\mV
V
mV
mV
A
A
A
V
%
mA
µF
dB
mV
µs
µs
ms
%
%
%
°C
°C
°C
V
M
Ω
pF
Notes & Conditions
continuous
continuous
Basic insulation, Pollution Degree 2
Input Voltage
Non-Operating
Operating
Isolation Voltage (input to output)
Operating Temperature
Storage Temperature
Voltage at ON/OFF input pin
-40
-55
-2
36
33.5
31.5
1
INPUT CHARACTERISTICS
Operating Input Voltage Range
Input Under-Voltage Lockout
Turn-On Voltage Threshold
Turn-Off Voltage Threshold
Lockout Voltage Hysteresis
Input Over-Voltage Shutdown
Turn-Off Voltage Threshold
Turn-On Voltage Threshold
Maximum Input Current
No-Load Input Current
Disabled Input Current
Inrush Current Transient Rating
Input Reflected Ripple Current
Input Terminal Ripple Current
Recommended Input Fuse
Input Filter Component Values (L\C)
Recommended External Input Capacitance
Output Voltage Set Point
Output Voltage Regulation
Over Line
Over Load
Over Temperature
Total Output Voltage Range
Output Voltage Ripple and Noise
Peak-to-Peak
RMS
Operating Output Current Range
Output DC Current-Limit Inception
Output DC Current-Limit Inception
Output DC Current-Limit Shutdown Voltage
Current Share Accuracy (2 units paralleled)
Back-Drive Current Limit while Disabled
Maximum Output Capacitance
Input Voltage Ripple Rejection
Output Voltage during Load Current Transient
For a Step Change in Output Current (0.1A/µs)
Settling Time
Turn-On Transient
Turn-On Time (without output capacitance)
Turn-On Time (with output capacitance)
Output Voltage Overshoot
100% Load
50% Load
Semiconductor Junction Temperature (see Note 1)
Board Temperature
Transformer Temperature
Isolation Voltage (dielectric strength)
Isolation Resistance
Isolation Capacitance
7.5
0.13
15
0.01
10
20
100% Load, 36 Vin
RMS through 10µH inductor; Figs. 23-24
RMS; Figs. 20-22
fast blow external fuse recommended
internal values, see Figure E
Typical ESR 0.1-0.2
Ω
, see Figure 20
48Vin, no load
OUTPUT CHARACTERISTICS
0
over sample, line, load, temperature & life
20MHz bandwidth
Full Load, see Figures 25-26
Full Load, see Figures 25-26
at 7.2Vout, 36Vin; subject to derating
36Vin,Output Voltage 10% Low; Fig. 19
55Vin,Output Voltage 10% Low; Fig. 19
% of rated output current
Negative current drawn from output
9.6Vout at 27A Resistive Load
Figure 28
50%-75%-50% Iout max; Figs 17-18
to within 1% Vout nom
Full load, Vout=90% nom., 0 output cap.
Full load, Vout=90% nom., 3,000 µF cap.
3,000 µF load cap., Iout = 0A, Vin nom.
Figures 1-4
Figures 1-4
Package rated to 175°C
Board rated to 165°C
See Figures 5 - 12 for derating curves
3,000
DYNAMIC CHARACTERISTICS
EFFICIENCY
TEMPERATURE LIMITS FOR POWER DERATING CURVES
ISOLATION CHARACTERISTICS
470
1. For normal operating conditions of 55°C ambient temperature and 200 LFM airflow. Device is designed to operate for a minimum of 72 hours, once per
year under the following conditions: 70°C, 200 LFM airflow, 36Vin, 240W output power. Junction temperature during those conditions will exceed the listed