SQT48T38096 DC-DC Converter Data Sheet
342-Watt @ 48 Vin, Eighth-Brick Bus Converter
Features
•
RoHS lead-free solder and lead-solder-exempted
products are available
•
Delivers up to 370 watts with a 55 VDC input
•
Industry-standard IBC quarter-brick pinout
•
5:1 Fixed ratio converter
•
Narrow input range 38-55 VDC
•
Parallel capability
•
0.480” (12.19 mm) height profile
•
On-board input differential LC-filter
•
Start up into pre-biased load
•
No minimum load required
•
Meets Basic Insulation requirements of EN60950
•
Operating ambient temperature: -40 °C to 85 °C
•
Fixed-frequency operation
•
Latching overcurrent protection
•
Fully protected (OTP, OCP, OVP, UVLO)
•
Positive or negative logic ON/OFF option
•
High reliability: MTBF = TBD million hours,
calculated per Telcordia TR-332, Method
I
Case 1
•
UL60950 recognized in US and Canada and
DEMKO certified per IEC/EN60950 (pending)
•
Designed to meet Class B conducted emissions per
FCC and EN55022 when used with external filter
•
All materials meet UL94, V-0 flammability rating
Applications
•
•
•
•
•
Intermediate Bus Architectures
Telecommunications
Data communications
Wireless communications
Servers, workstations
Benefits
•
•
•
•
High efficiency – no heat sink required
Cost-effective, single board design
Reduces total solution board area
2
Extremely small footprint: 0.896” x 2.30” (2.06 in ),
38% smaller than conventional quarter-bricks
Description
The new 38 A SQT48 eighth-brick Intermediate Bus Converter (IBC) provides an ultra-high efficiency single output
that is only 62% the size of the industry-standard quarter-brick IBC, while still preserving the same pinout and
functionality. Inclusion of this converter in a new design can result in significant board space and cost savings.
Operating from a 38 to 55 VDC input, the SQT48T38096 IBC provides a 5:1 fixed ratio, isolated, step-down
voltage. Output voltage is directly proportional to input voltage with a conversion ratio of 5:1 at 48 VDC; the
resulting output voltage would be 9.6 VDC. The converter has paralleling capability with accurate current sharing.
The 38A SQT48 IBC provides outstanding thermal performance in high temperature environments. This
performance is accomplished through the use of patented/patent-pending power electronic circuits, packaging,
and processing techniques to achieve ultra-high efficiency, excellent thermal management, and a low-body profile.
The designer can expect system reliability improvements over other available converters because of the 38A
SQT48 IBC’s optimized thermal efficiency which is due to the use of a multi-layer PWB and the extensive use of
heavy copper plating. The low-body profile minimizes airflow shadowing, thus enhancing cooling for both upstream
and downstream devices. The use of 100% automation for assembly, coupled with advanced electronic circuits
and thermal design, results in a product with extremely high reliability.
.
FEB 17, 2006 revised to NOV 03, 2006
Page 1 of 11
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SQT48T38096 DC-DC Converter Data Sheet
342-Watt @ 48 Vin, Eighth-Brick Bus Converter
Electrical Specifications
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vi n = 48 VDC, unless otherwise specified.
Parameter
Absolute Maximum Ratings
Input Voltage
Isolation Voltage (input to output)
Operating Ambient Temperature
Storage Temperature
Voltage at ON/OFF Input Pin
Input Characteristics
Operating Input Voltage Range
Input Undervoltage Lockout
Turn-on Threshold
Turn-off Threshold
Input Overvoltage Lockout
Shutdown Threshold
Restart Threshold
Maximum Input Current
Input No Load Current
Disabled Input Current
Input Reflected-Ripple Current
Input Terminal-Ripple Current
Input Filter Component Values (L\C)
Recommended External Input Capacitance
Output Characteristics
1
Total Output Voltage Range
(Over Line, Load and Temperature)
Output Voltage Regulation Over Load
Output Ripple and Noise
Peak-to-Peak
RMS
Maximum Output Capacitance
Operating Output Current Range
Output DC Current Limit Inception
Output Short Circuit Protection
Current Share Accuracy (2 units in parallel)
Latching
Latching
Continuous
Notes
Min
0
2000
-40
-55
-20
38
35.5
32
Typ
Max
60
85
125
20
Units
V
V
°C
°C
V
V
V
V
V
V
A
mA
mA
mArms
mA
µH\µF
µF
Basic level, Pollution Degree
With appropriate power derating
48
55
38
34.5
60
58
7.8
Vin when unit will shut down
Vin when unit turns on after shutdown event
Full load @ 38 VDC In
57
55
80
16
100
20
5
220
RMS through 10 µH inductor, Pout = 240 W
RMS, Pout = 240 W
Internal values
47
2.5
150
1.0\3.2
100
From Vin = 38 V to Vin = 55 V
7
0.42
11
0.5
150
30
3000
38
47
5
56
10
VDC
V
mV
mV
µF
A
A
%
20 MHz bandwidth, C
OUT
= 15 µF tantalum
75
15
0
40
% of rated output current
Additional Notes:
1
The Output Voltage under any combination of Vin and load current can be calculated as
Vout
=
Vin
5.05
−
Iout
90
.
FEB 17, 2006 revised to NOV 03, 2006
Page 2 of 11
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SQT48T38096 DC-DC Converter Data Sheet
342-Watt @ 48 Vin, Eighth-Brick Bus Converter
Electrical Specifications
(continued)
Conditions: T
A
= 25 ºC, Airflow = 300 LFM (1.5 m/s), Vin = 48 VDC, unless otherwise specified.
Parameter
Dynamic Response
Load Change 25%-50%-25%, di/dt = 1 A/µs
Efficiency
100% Load
50% Load
Isolation Characteristics
I/O Isolation Voltage
Isolation Resistance
Isolation Capacitance
Feature Characteristics
Switching Frequency
Turn-On Delay Time
2
Notes
Co = 4 µF/W of output power
Iout = 38 A
Iout = 19 A
Min
Typ
Max
+/-3
Units
%
%
%
VDC
95.2
95.3
2000
30
230
M•
pF
kHz
ms
ms
ms
0.8
20
20
0.8
VDC
VDC
VDC
VDC
VDC
Ripple frequency
Full resistive load
From Vin = Vin(min) to Vo = 0.1* Vo(nom)
From enable to Vo = 0.1*Vo(nom)
From 10% to 90%, full resistive load
-20
2.4
2.4
-20
Non-latching
400
0.7
0.7
1
With Vin = (Unit Enabled, then Vin applied)
With Enable (Vin = Vin(nom) applied, then
enabled)
Rise time
2
ON/OFF Control (Positive Logic)
Converter Off
Converter On
ON/OFF Control (Negative Logic)
Converter Off
Converter On
Output Overvoltage Protection
Additional Notes:
2
11.7
12
Note that startup time is the sum of turn-on delay time and rise time.
FEB 17, 2006 revised to NOV 03, 2006
Page 3 of 11
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SQT48T38096 DC-DC Converter Data Sheet
342-Watt @ 48 Vin, Eighth-Brick Bus Converter
Operations
Input and Output Impedance
These power converters have been designed to be
stable with no external capacitors when used in low
inductance input and output circuits.
In many applications, the inductance associated with
the distribution from the power source to the input of
the converter can affect the stability of the converter.
The addition of a 47-100 µF electrolytic capacitor
with an ESR < 1 • across the input helps to ensure
stability of the converter. In many applications, the
user has to use decoupling capacitance at the load.
The power converter will exhibit stable operation with
external load capacitance up to 3,000 µF on 9.6 V
output.
Additionally, see the EMC section of this data sheet
for discussion of other external components which
may be required for control of conducted emissions.
Parallel Operation
The converter is capable paralleling of several units
with current sharing. A typical circuit for two
converters in parallel is shown on Fig. A. The input
capacitors should be placed close to the input pins of
the converters. Inductors L1 and L2 (1.0 µH to
4.7 µH) are not required, but they are recommended
to reduce the input ripple current and EMI
performance.
L1
Vin (+)
Vout (+)
4.
The under voltage lockout startup point will
slightly vary from unit to unit, therefore the dv/dt
of the input source as it rises from 0 V to its final
value will affect the ability of the parallel units to
turn on into a load equal to more that the
maximum rated load of one unit. The dv/dt of
the rising edge of the input voltage must be
greater than 2 V/ms. It is strongly recommended
that the maximum load current be limited to the
maximum current rating of a single converter
until the output voltage exceeds 90% of the
rated output voltage.
Note that the maximum power available will be
reduced by up to 10% due to current share
accuracy.
5.
ON/OFF (Pin 2)
The ON/OFF pin is used to turn the power converter
on or off remotely via a system signal. There are two
remote control options available, positive and
negative logic, with both referenced to Vin(-). A
typical connection is shown in Fig. B.
Vin (+)
Vout (+)
SQT48 Converter
(Top View)
Vin
ON/OFF
Rload
Vin (-)
CONTROL
INPUT
Vout (-)
SQT48 Converter
Vin
(N-Logic Option)
ON/OFF
Vin (-)
Vout (-)
Fig. B: Circuit configuration for ON/OFF function.
Vout
L2
Vin (+)
Vout (+)
SQT48 Converter
ON/OFF
Vin (-)
(N-Logic Option)
Vout (-)
The positive logic version turns on when the ON/OFF
pin is at a logic high and turns off when at a logic
low. The converter is on when the ON/OFF pin is left
open. See the Electrical Specification section for
logic high/low definitions.
The negative logic version turns on when the pin is
at a logic low and turns off when the pin is at a logic
high. The ON/OFF pin can be hardwired directly to
Vin(-) to enable automatic power up of the converter
without the need of an external control signal.
The ON/OFF pin is internally pulled up to 5 V
through a resistor. A properly de-bounced
mechanical switch, open-collector transistor, or FET
can be used to drive the input of the ON/OFF pin.
The device must be capable of sinking up to 0.2 mA
at a low level voltage of
≤
0.8 V. An external voltage
source (±20 V maximum) may be connected directly
to the ON/OFF input, in which case it must be
capable of sourcing or sinking up to 1 mA depending
on the signal polarity.
Fig. A: Paralleling for increased current output.
The following precautions must be observed when
operating several converters in parallel:
1.
2.
The inputs of all converters must be attached to
the same voltage source.
The PCB trace resistance from each unit to the
load (Vout+ and Vout- traces) should be
equalized as much as is practical. The same
should be done with the input trace resistances
(Vin+ and Vin-) to enhance the current sharing
accuracy.
The ON/OFF pins of the converters must be tied
together and operated as a single converter.
3.
FEB 17, 2006 revised to NOV 03, 2006
Page 4 of 11
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SQT48T38096 DC-DC Converter Data Sheet
342-Watt @ 48 Vin, Eighth-Brick Bus Converter
Protection Features
Input Undervoltage and Overvoltage Lockout
Input undervoltage lockout is standard with this
converter. The converter will shut down when the
input voltage drops below a pre-determined voltage.
The converter will shut down when the input voltage
exceeds typically 58.5 V, thus automatically
providing output overvoltage protection. Because the
transformer’s ratio is 5:1, the output voltage will be
typically limited to 11.7 V. The converter will restart
when the input voltage drops typically below 56.5 V.
Output Overcurrent Protection (OCP)
The converter is protected against overcurrent or
short circuit conditions. Upon sensing an overcurrent
condition, the converter will latch off. In order to
restart converter either ON/OFF pin or input voltage
need to be recycled.
Overtemperature Protection (OTP)
The converter will shut down under an
overtemperature condition to protect itself from
overheating caused by operation outside the thermal
derating curves, or operation in abnormal conditions
such as system fan failure. After the converter has
cooled to a safe operating temperature, it will
automatically restart.
Safety Requirements
The converter meets North American and
International safety regulatory requirements per
UL60950 and EN60950 (pending). Basic Insulation is
provided between input and output.
To comply with safety agencies’ requirements, an
input line fuse must be used external to the
converter. A 15 A fast blow fuse is recommended for
use with a standalone SQT48T38096 converter.
Electromagnetic Compatibility (EMC)
EMC requirements must be met at the end-product
system level, as no specific standards dedicated to
EMC characteristics of board mounted component
dc-dc converters exist. However, Power-One tests its
converters to several system level standards,
primary of which is the more stringent EN55022,
Information
technology
equipment
-
Radio
disturbance characteristics-Limits and methods of
measurement.
An effective internal LC differential filter significantly
reduces input reflected ripple current, and improves
EMC.
With the addition of a simple external filter, all
versions of the SQT-Series of converters pass the
requirements of Class B conducted emissions per
EN55022 and FCC requirements. Please contact
Power-One Applications Engineering for details of
this testing.
Characterization
General Information
The converter has been characterized for many
operational aspects, to include thermal derating
(maximum load current as a function of ambient
temperature and airflow) for vertical or horizontal
mounting, efficiency, startup and shutdown
parameters, output ripple and noise, transient
response to load step-change, overload, and short
circuit.
The following pages contain specific plots or
waveforms associated with the converter. Additional
comments for specific data are provided below.
Test Conditions
All data presented were taken with the converter
soldered to a test board, specifically a 0.060” thick
printed wiring board (PWB) with four layers. The top
and bottom layers were not metalized. The two inner
layers, comprised of two-ounce copper, were used to
provide traces for connectivity to the converter.
The lack of metalization on the outer layers as well
as the limited thermal connection ensured that heat
transfer from the converter to the PWB was
minimized. This provides a worst-case but consistent
scenario for thermal derating purposes.
All measurements requiring airflow were made in the
vertical and horizontal wind tunnels using Infrared
(IR)
thermography
and
thermocouples
for
thermometry.
Ensuring components on the converter do not
exceed their ratings is important to maintaining high
reliability. If one anticipates operating the converter
at or close to the maximum loads specified in the
derating curves, it is prudent to check actual
operating
temperatures
in
the
application.
Thermographic imaging is preferable; if this
capability is not available, then thermocouples may
be used. The use of AWG #40 gauge thermocouples
is recommended to ensure measurement accuracy.
Careful routing of the thermocouple leads will further
minimize measurement error. Refer to Fig. C for the
optimum measuring thermocouple locations.
FEB 17, 2006 revised to NOV 03, 2006
Page 5 of 11
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