Data Sheet
January 2000
FC250B1 Power Module: dc-dc Converter;
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
The FC250B1 Power Module uses advanced, surface-mount
technology and delivers high-quality, compact, dc-dc conver-
sion at an economical price.
Applications
■Redundant and distributed power architectures
■Computer equipment
■communications equipment
Options
■Heat sinks available for extended operation
Features
■Size: 61.0 mm x 116.8 mm x 13.5 mm
(2.40 in. x 4.60 in. x 0.53 in.)
■Wide input voltage range
■High efficiency: 84% typical
■Parallel operation with load sharing
■Adjustable output voltage
■Overtemperature protection
■Synchronization
■power good signal
■Output current monitor
■Output overvoltage and overcurrent protection
■Remote sense
■Remote on/off
■Constant frequency
■Case ground pin
■Input-to-output isolation
■
ISO
* 9001 Certified manufacturing facilities
■
UL
†1950 Recognized,
CSA
‡ C22.2 No. 950-95
Certified, and
VDE
§ 0805 (EN60950, IEC950)
Licensed
Description
The FC250B1 Power Module is a dc-dc converter that operates over an input voltage range of 18 Vdc to 36 Vdc
and provides a precisely regulated dc output. The outputs are fully isolated from the inputs, allowing versatile
polarity configurations and grounding connections. The module has a maximum power rating of 250 W at a typ-
ical full-load efficiency of 84%.
Two or more modules may be paralleled with forced load sharing for redundant or enhanced power applica-
tions. The package, which mounts on a printed-circuit board, accommodates a heat sink for high-temperature
applications.
*
ISO
is a registered trademark of the International Organization for Standardization.
†
UL
is a registered trademark of Underwriters Laboratories, Inc.
‡
CSA
is a registered trademark of Canadian Standards Assn.
§
VDE
is a trademark of Verband Deutscher Elektrotechniker e.V.
22 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent damage to the device. These are abso-
lute 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 device reliability.
Electrical Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature
conditions.
Table 1. Input Specifications
Fusing Considerations
CAUTION: This power module is not internally fused. An input line fuse must always be used.
This encapsulated power module can be used in a wide variety of applications, ranging from simple stand-alone
operation to an integrated part of a sophisticated power architecture. To preserve maximum flexibility, internal fus-
ing is not included; however, to achieve maximum safety and system protection, always use an input line fuse. The
safety agencies require a normal-blow fuse with a maximum rating of 25 A (see Safety Considerations section).
Parameter Symbol Min Max Unit
Input Voltage (continuous) VI—50Vdc
I/O Isolation Voltage (for 1 minute) — — 1500 V
Operating Case Temperature
(See Thermal Considerations section and
Figure18.)
TC–40 100 °C
Storage Temperature Tstg –55 125 °C
Parameter Symbol Min Typ Max Unit
Operating Input Voltage VI18 28 36 Vdc
Maximum Input Current (VI = 0 V to 36 V) II, max ——24 A
Inrush Transient i2t——4.0A
2s
Input Reflected-ripple Current, Peak-to-peak
(5 Hz to 20 MHz, 12 µH source impedance: see
Figure 8.)
II—10—mAp-p
Input Ripple Rejection (120 Hz) — — 60 — dB
Tyco Electronics Corp. 3
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Electrical Specifications (continued)
Table 2. Output Specifications
* Consult your sales representative or the factory.
†These are manufacturing test limits. In some situations, results may differ.
Parameter Symbol Min Typ Max Unit
Output Voltage Set Point
(VI = 28 V; IO = IO, max; TC = 25 °C)
VO, set 11.82 12.0 12.18 Vdc
Output Voltage
(Over all operating input voltage, resistive load, and
temperature conditions until end of life; see Figure 10
and Feature Descriptions.)
VO11.64 — 12.36 Vdc
Output Regulation:
Line (VI = 18 V to 36 V)
Load (IO = IO, min to IO, max )
Temperature (TC = –40 °C to +100 °C)
—
—
—
—
—
—
0.01
0.05
50
0.1
0.2
100
%VO
%VO
mV
Output Ripple and Noise Voltage
(See Figures 4 and 9.):
RMS
Peak-peak (5 Hz to 20 MHz)
—
—
—
—
—
—
50
150
mVrms
mVp-p
External Load Capacitance — 0 — * µF
Output Current
(At IO < IO, min, the modules may exceed output
ripple specifications.)
IO0.3 — 20.8 A
Output Current-limit Inception
(VO = 90% of VO, set ; see Feature Descriptions.)
IO, cli 103 — 130†%IO, max
Output Short-circuit Current
(VO = 1.0 V; indefinite duration, no hiccup mode; see
Figure 2.)
———150%I
O, max
Efficiency
(VI = 28 V; IO = IO, max; TC = 25 °C;
see Figures 3 and 10.)
η—84.5— %
Switching Frequency — — 500 — kHz
Dynamic Response
(∆IO/∆t = 1 A/10 µs, VI = 28 V, TC = 25 °C; tested with a
10 µF aluminum and a 1.0 µF ceramic capacitor across
the load; see Figures 5 and 6.):
Load Change from IO = 50% to 75% of IO, max:
Peak Deviation
Settling Time (VO < 10% of peak deviation)
Load Change from IO = 50% to 25% of IO, max:
Peak Deviation
Settling Time (VO < 10% of peak deviation)
—
—
—
—
—
—
—
—
500
150
500
150
—
—
—
—
mV
µs
mV
µs
44 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Electrical Specifications (continued)
Table 3. Isolation Specifications
General Specifications
Feature Specifications
Unless otherwise indicated, specifications apply over all operating input voltage, resistive load, and temperature
conditions. See Feature Descriptions for further information.
Table 4. Feature Specifications
* These are manufacturing test limits. In some situations, results may differ.
Parameter Min Typ Max Unit
Isolation Capacitance — 1700 — pF
Isolation Resistance 10 — — MΩ
Parameter Min Typ Max Unit
Calculated MTBF (IO = 80% of IO, max; TC = 40 °C) 1,800,000 hours
Weight — — 200 (7) g (oz.)
Parameter Symbol Min Typ Max Unit
Remote On/Off Signal Interface
(VI = 0 V to 36 V; open collector or equivalent
compatible; signal referenced to VI(–) terminal; see
and Feature Descriptions.):
Logic Low—Module On
Logic High—Module Off
Logic Low:
At Ion/off = 1.0 mA
At Von/off = 0.0 V
Logic High:
At Ion/off = 0.0 µA
Leakage Current
Turn-on Time
(IO = 80% of IO, max; VO within ±1% of steady state)
Output Voltage Overshoot
Von/off
Ion/off
Von/off
Ion/off
—
—
0
—
—
—
—
—
—
—
—
—
30
0
1.2
1.0
15
50
50
5
V
mA
V
µA
ms
%VO, set
Output Voltage Adjustment (See Feature Descriptions.):
Output Voltage Remote-sense Range
Output Voltage Set-point Adjustment Range (trim)
—
—
—
60
—
—
1.2
110
V
%VO, nom
Output Overvoltage Protection — 13.5* — 16.0* V
Output Current Monitor (IO = IO, max, TC = 70 °C) IO, mon —0.18—V/A
Synchronization:
Clock Amplitude
Clock Pulse Width
Fan-out
Capture Frequency Range
—
—
—
—
4.00
0.4
—
450
—
—
—
—
5.00
—
1
550
V
µs
—
kHz
Tyco Electronics Corp. 5
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Feature Specifications (continued)
Table 4. Feature Specifications (continued)
Solder, Cleaning, and Drying Considerations
Post solder cleaning is usually the final circuit-board assembly process prior to electrical testing. The result of inad-
equate circuit-board 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
Tyco Electronics
Board-Mounted Power Modules Soldering and Cleaning
Application Note (AP97-021EPS).
Parameter Symbol Min Typ Max Unit
Overtemperature Protection
(See Figure 18.)
TC—105— °C
Forced Load Share Accuracy — — 10 — %IO, rated
Power Good Signal Interface
(See Feature Descriptions.):
Low Impedance—Module Operating
High Impedance—Module Off
Rpwr/good
Ipwr/good
Rpwr/good
Vpwr/good
—
—
1
—
—
—
—
—
100
1
—
40
Ω
mA
MΩ
V
66 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Characteristic Curves
The following figures provide typical characteristics for the power module.
8-2166 (C)
Figure 1. Typical FC250B1 Input Characteristics at
Room Temperature
8-1658 (C)
Figure 2. Typical FC250B1 Output Characteristics
at Room Temperature
8-1659 (C)
Figure 3. Typical FC250B1 Efficiency vs. Output
Current at Room Temperature
8-1660 (C)
Note: See figure 9 for test conditions.
Figure 4. Typical FC250B1 Output Ripple Voltage
at Room Temperature and Full Load
Output
51015
0
16
INPUT VOLTAGE, V I (V)
2
4
INPUT CURRENT, II (A)
20
400
18
20 25 30 35
IO = 2.08 A
8
10
12
14
6
IO = 20.84 A
IO = 10.42 A
11.0
8.0
2.0
2 6
0.0
6.0
OUTPUT CURRENT, I O (A)
3.0
1.0
9.0
10.0
7.0
4.0
4
5.0
12.0
8 1012 1416182002224262830
OUTPUT VOLTAGE, V O (V)
VI = 18 V
VI = 27 V
VI = 36 V
85
83
80
2 4 12 14 16 18
78
OUTPUT CURRENT, I O (A)
81
82
79
86
200 8 106
84
VI = 18 V
VI = 27 V
VI = 36 V
EFFICIENCY , η (%)
TIME, t (500 ns/div)
OUTPUT VOLTAGE, VO (V)
(10 mV/div)
VI = 18 V
VI = 24 V
VI = 36 V
Tyco Electronics Corp. 7
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Characteristic Curves (continued)
8-1661 (C)
Note: Tested With a 10 µF tantalum and a 1.0 µF ceramic capacitor
across the load.
Figure 5. Typical FC250B1 Transient Response to
Step Decrease in Load from 50% to 25%
of Full Load at Room Temperature and
28 V Input (Waveform Averaged to
Eliminate Ripple Component.)
8-1664 (C)
Note: Tested With a 10 µF aluminum and a 1.0 µF ceramic capacitor
across the load.
Figure 6. Typical FC250B1 Transient Response to
Step Decrease in Load from 50% to 75%
of Full Load at Room Temperature and
28 V Input (Waveform Averaged to
Eliminate Ripple Component.)
8-1663 (C)
Note: Tested With a 10 µF tantalum and a 1.0 µF ceramic capacitor
across the load.
Figure 7. Typical FC250B1 Start-Up Transient at
Room Temperature, 28 V Input
TIME, t (50 µs/div)
OUTPUT VOLTAGE, VO (V)
(500 mV/div)
OUTPUT CURRENT, IO
(A)
(5 A/div)
5.2
10.4
12.0
0.0
TIME, t (50 µs/div)
OUTPUT VOLTAGE, VO (V)
(500 mV/div)
OUTPUT CURRENT, IO
(A)
(5 A/div)
10.4
12.0
0.0
15.6
TIME, t (5 ms/div)
OUTPUT VOLTAGE, VO (V)
(5 V/div)
REMOTE ON/OFF, VON/OFF
(V)
88 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Test Configurations
8-203 (C).o
Note: Measure input reflected-ripple current with a simulated source
inductance (Ltest) of 12 µH. Capacitor Cs offsets possible bat-
tery impedance. Measure current as shown above.
Figure 8. Input Reflected-Ripple Test Setup
8-513 (C).m
Note: Use a 0.1 µF ceramic capacitor and a 10 µF aluminum or
tantalum capacitor. Scope measurement should be made
using a BNC socket. Position the load between 50 mm and
76 mm (2 in. and 3 in.) from the module.
Figure 9. Peak-to-Peak Output Noise
Measurement Test Setup
8-683 (C).f
Note: All measurements are taken at the module terminals. When
socketing, place Kelvin connections at module terminals to
avoid measurement errors due to socket contact resistance.
Figure 10.Output Voltage and Efficiency
Measurement Test Setup
Design Considerations
Input Source Impedance
The power module should be connected to a low ac-
impedance input source. Highly inductive source
impedances can affect the stability of the power mod-
ule. For the test configuration in Figure 8, a 100 µF
electrolytic capacitor (ESR < 0.3 Ω at 100 kHz)
mounted close to the power module helps ensure sta-
bility of the unit. For other highly inductive source
impedances, consult the factory for further application
guidelines.
Safety Considerations
For safety-agency approval of the system in which the
power module is used, the power module must be
installed in compliance with the spacing and separation
requirements of the end-use safety agency standard,
i.e.,
UL
1950,
CSA
C22.2 No. 950-95, and
VDE
0805
(EN60950, IEC950).
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 maxi-
mum 25 A normal-blow fuse in the ungrounded lead.
Feature Descriptions
Overcurrent Protection
To provide protection in a fault (output overload) condi-
tion, the unit is equipped with internal current-limiting
circuitry and can endure current limiting for an unlim-
ited duration. At the point of current-limit inception, the
unit shifts from voltage control to current control. If the
output voltage is pulled very low during a severe fault,
the current-limit circuit can exhibit either foldback or
tailout characteristics (output-current decrease or
increase). The unit operates normally once the output
current is brought back into its specified range.
TO OSCILLOSCOPE
12 µH
C
S
220 µF
ESR < 0.1 Ω
@ 20 ˚C, 100 kHz
V
I(+)
VI
(-)
BATTERY 100 µF
L
TEST
ESR < 0.3 Ω
@ 100 kHz
V
O
(+)
V
O
(–)
1.0 µF RESISTIVE
LOAD
SCOPE
COPPER STRIP
10 µF
LOAD
CONTACT AND
SUPPLY II
CONTACT
VI(+)
VI(–)
SENSE(+)
SENSE(–)
VO(+)
VO(–)
DISTRIBUTION LOSSESRESISTANCE
IO
η[VO(+) VO(–)]IO
–
[VI(+) VI(–)]II
–()
-----------------------------------------------
100×=%
Tyco Electronics Corp. 9
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Feature Descriptions (continued)
Remote On/Off
To turn the power module on and off, the user must
supply a switch to control the voltage between the on/
off terminal and the VI(–) terminal (Von/off). The switch
can be an open collector or equivalent (see Figure 11).
A logic low is Von/off = 0. V to 1.2 V, during which the
module is on. The maximum Ion/off during a logic low is
1 mA. The switch should maintain a logic-low voltage
while sinking 1 mA.
During a logic high, the maximum Von/off generated by
the power module is 15 V. The maximum allowable
leakage current of the switch at Von/off = 15 V is 50 µA.
If not using the remote on/off feature, short the
ON/OFF pin to VI(–).
8-580 (C).d
Figure 11. Remote On/Off Implementation
Remote Sense
Remote sense minimizes the effects of distribution
losses by regulating the voltage at the remote-sense
connections. The voltage between the remote-sense
pins and the output terminals must not exceed the out-
put voltage sense range given in the Feature Specifica-
tions table, i.e.:
[VO(+) – VO(–)] – [SENSE(+) – SENSE(–)] ≤ 1.2 V
The voltage between the VO(+) and VO(–) terminals
must not exceed the minimum value indicated in the
output overvoltage shutdown section of the Feature
Specifications table. This limit includes any increase in
voltage due to remote-sense compensation and output
voltage set-point adjustment (trim), see Figure 12.
If not using the remote-sense feature to regulate the
output at the point of load, connect SENSE(+) to V
O(+)
and SENSE(–) to VO(–) at the module.
Although the output voltage can be increased by both
the remote sense and by the trim, the maximum
increase for the output voltage is not the sum of both.
The maximum increase is the larger of either the
remote sense or the trim. consult the factory if you
need to increase the output voltage more than the
above limitation.
The amount of power delivered by the module is
defined as the voltage at the output terminals multiplied
by the output current. when using remote sense and
trim, the output voltage of the module can be
increased, which at the same output current would
increase the power output of the module. Care should
be taken to ensure that the maximum output power of
the module remains at or below the maximum rated
power.
8-651 (C).e
Figure 12.Effective Circuit Configuration for
Single-Module Remote-Sense Operation
Output Voltage Set-Point Adjustment
(Trim)
Output voltage trim allows the user to increase or
decrease the output voltage set point of a module. This
is accomplished by connecting an external resistor
between the TRIM pin and either the SENSE(+) or
SENSE(–) pins. the trim resistor should be positioned
close to the module.
If not using the trim feature, leave the TRIM pin open.
With an external resistor between the TRIM and
SENSE(–) pins (Radj-down), the output voltage set point
(VO, adj) decreases (see Figure 13). The following equa-
tion determines the required external-resistor value to
obtain a percentage output voltage change of ∆%.
The test results for this configuration are displayed in
Figure 14. this figure applies to all output voltages.
+
ION/OFF
–
VON/OFF
CASE
ON/OFF
VI (+)
VI (–)
SENSE(+)
SENSE(–)
VO (+)
VO (–)
V
O
(+)
SENSE(+)
SENSE(–)
V
O
(–)
V
I
(+)
V
I
(-)
I
O
LOAD
CONTACT AND
DISTRIBUTION LOSSE
S
SUPPLY I
I
CONTACT
RESISTANCE
Radj-down
198
∆%
---------2.1892–
=kΩ
1010 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Feature Descriptions (continued)
Output Voltage Set-Point Adjustment
(Trim) (continued)
With an external resistor connected between the TRIM
and SENSE(+) pins (Radj-up), the output voltage set
point (VO, adj) increases (see Figure 15).
The following equation determines the required exter-
nal-resistor value to obtain a percentage output voltage
change of ∆%.
The test results for this configuration are displayed in
Figure 16.
The voltage between the VO(+) and VO(–) terminals
must not exceed the minimum value of the output over-
voltage protection as indicated in the Feature Specifi-
cations table. This limit includes any increase in voltage
due to remote-sense compensation and output voltage
set-point adjustment (trim). See Figure 12.
Although the output voltage can be increased by both
the remote sense and by the trim, the maximum
increase for the output voltage is not the sum of both.
The maximum increase is the larger of either the
remote sense or the trim. Consult the factory if you
need to increase the output voltage more than the
above limitation.
The amount of power delivered by the module is
defined as the voltage at the output terminals multiplied
by the output current. When using remote sense and
trim, the output voltage of the module can be
increased, which at the same output current would
increase the power output of the module. Care should
be taken to ensure that the maximum output power of
the module remains at or below the maximum rated
power.
8-748 (C).b
Figure 13.Circuit Configuration to Decrease
Output Voltage
8-1959 (C)
Figure 14.Resistor Selection for Decreased Output
Voltage
8-715 (C).b
Figure 15.circuit Configuration to Increase
Output Voltage
8-1960 (C)
Figure 16.Resistor Selection for Increased Output
Voltage
Radj-up
(VO, nom 1∆%
100
---------
+
– 1.225)
1.225∆%()
------------------------------------------------------------------ 205 – 2.225
kΩ=
VI
(+)
VI(–)
ON/OFF
CASE
VO(+)
VO(–)
SENSE(+)
TRIM
SENSE(–)
Radj-down
RLOAD
010203040
1k
PERCENT CHANGE IN OUTPUT VOLTAGE (∆%)
ADJUSTMENT RESISTOR VALUE (Ω)
100
10
1
VI(+)
VI(–)
ON/OFF
CASE
VO(+)
VO(-)
SENSE(+)
TRIM
SENSE(–)
Radj-up
RLOAD
02 4 6 8
10k
PERCENT CHANGE IN OUTPUT VOLTAGE (∆%)
ADJUSTMENT RESISTOR VALUE (Ω)
1k
100
10
10
Tyco Electronics Corp. 11
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Feature Descriptions (continued)
Output Overvoltage Protection
The output voltage is monitored at the VO(+) and VO(–)
pins of the module. If the voltage at these pins exceeds
the value indicated in the Feature Specifications table,
the module will shut down and latch off. Recovery from
latched shutdown is accomplished by cycling the dc
input power off for at least 1.0 second or toggling the
primary referenced on/off signal for at least 1.0 second.
Output current Monitor
The CURRENT MON pin provides a dc voltage propor-
tional to the dc output current of the module given in
the Feature Specifications table. For example, on the
FC250B1, the V/A ratio is set at 180 mV/A ± 10% @
70 °C case. At a full load current of 20.8 A, the voltage
on the CURRENT MON pin is 3.744 V. The current
monitor signal is referenced to the SENSE(–) pin on
the secondary and is supplied from a source imped-
ance of approximately 2 kΩ. It is recommended that the
CURRENT MON pin be left open when not in use,
although no damage will result if the CURRENT MON
pin is shorted to secondary ground. Directly driving the
CURRENT MON pin with an external source will detri-
mentally affect operation of the module and should be
avoided.
Synchronization
Any module can be synchronized to any other module
or to an external clock using the SYNC IN or SYNC
OUT pins. The modules are not designed to operate in
a master/slave configuration; that is, if one module fails,
the other modules will continue to operate.
SYNC IN Pin
This pin can be connected either to an external clock or
directly to the SYNC OUT pin of another FC250x mod-
ule.
If an external clock signal is applied to the SYNC IN
pin, the signal must be a 500 kHz (±50 kHz) square
wave with a 4 Vp-p amplitude. Operation outside this
frequency band will detrimentally affect the perfor-
mance of the module and must be avoided.
If the SYNC IN pin is connected to the SYNC OUT pin
of another module, the connection should be as direct
as possible, and the VI(–) pins of the modules must be
shorted together.
Unused SYNC IN pins should be tied to VI(–). If the
SYNC IN pin is unused, the module will operate from
its own internal clock.
SYNC OUT Pin
This pin contains a clock signal referenced to the VI(–)
pin. The frequency of this signal will equal either the
module’s internal clock frequency or the frequency
established by an external clock applied to the SYNC
IN pin.
When synchronizing several modules together, the
modules can be connected in a daisy-chain fashion
where the SYNC OUT pin of one module is connected
to the SYNC IN pin of another module. Each module in
the chain will synchronize to the frequency of the first
module in the chain.
To avoid loading effects, ensure that the SYNC OUT
pin of any one module is connected to the SYNC IN pin
of only one module. Any number of modules can be
synchronized in this daisy-chain fashion.
Overtemperature Protection
To provide protection in a fault condition, the unit is
equipped with an overtemperature shutdown circuit.
The shutdown circuit will not engage unless the unit is
operated above the maximum case temperature.
Recovery from overtemperature shutdown is
accomplished by cycling the dc input power off for at
least 1.0 second or toggling the primary referenced on/
off signal for at least 1.0 second.
Forced Load Sharing (Parallel Operation)
For either redundant operation or additional power
requirements, the power modules can be configured for
parallel operation with forced load sharing (see
Figure 17). For a typical redundant configuration,
Schottky diodes or an equivalent should be used to
protect against short-circuit conditions. Because of the
remote sense, the forward-voltage drops across the
Schottky diodes do not affect the set point of the volt-
age applied to the load. For additional power require-
ments, where multiple units are used to develop
combined power in excess of the rated maximum, the
Schottky diodes are not needed.
1212 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Feature Descriptions (continued)
Forced Load Sharing (Parallel Operation)
(continued)
Good layout techniques should be observed for noise
immunity. To implement forced load sharing, the follow-
ing connections must be made:
■The parallel pins of all units must be connected
together. The paths 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
SENSE(+) pins to the (+) side of the power bus at the
same point and all SENSE(–) pins to the (–) side of
the power bus at the same point. Close proximity and
directness are necessary for good noise immunity.
When not using the parallel feature, leave the
PARALLEL pin open.
8-581 (C)
Figure 17.Wiring Configuration for redundant
Parallel Operation
Power Good Signal
The PWR GOOD pin provides an open-drain signal
(referenced to the SENSE(–) pin) that indicates the
operating state of the module. A low impedance
(<100 Ω) between PWR GOOD and SENSE(–) indi-
cates that the module is operating. A high impedance
(> 1 MΩ) between PWR GOOD and SENSE(–) indi-
cates that the module is off or has failed. The PWR
GOOD pin can be pulled up through a resistor to an
external voltage to facilitate sensing. This external volt-
age level must not exceed 40 V, and the current into the
PWR GOOD pin during the low-impedance state
should be limited to 1 mA maximum.
Thermal Considerations
Introduction
The power modules operate in a variety of thermal
environments; however, sufficient cooling should be
provided to help ensure reliable operation of the unit.
Heat-dissipating components inside the unit are ther-
mally coupled to the case. Heat is removed by conduc-
tion, convection, and radiation to the surrounding
environment. Proper cooling can be verified by mea-
suring the case temperature. Peak temperature occurs
at the position indicated in Figure 18.
8-1303 (C).a
Note: Top view, measurements shown in millimeters and (inches).
Pin locations are for reference only.
Figure 18.Case Temperature Measurement
Location
VO(+)
PARALLEL
SENSE(+)
SENSE(–)
VO(–)
CASE
VI(+)
ON/OFF
VI(–)
VO(+)
PARALLEL
SENSE(+)
SENSE(–)
VO(–)
CASE
VI(+)
ON/OFF
VI(–)
30.5
(1.20)
82.6
(3.25)
CASE
SYNC IN
VI(-)
VI(+) VO(+)
VO(-)
SYNC OUT
MEASURE CASE
TEMPERATURE HERE
ON/OFF
Tyco Electronics Corp. 13
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Thermal Considerations (continued)
Introduction (continued)
The temperature at this location should not exceed
100 °C. the maximum case temperature can be limited
to a lower value for extremely high reliability. The output
power of the module should not exceed the rated
power for the module as listed in the Ordering Informa-
tion table.
For additional information about these modules, refer to
the Tyco Electronics
Thermal Management for FC- and
FW-Series 250 W—300 W Board-Mounted Power
Modules
Technical Note (TN96-009EPS).
Heat Transfer Without Heat Sinks
Derating curves for forced-air cooling without a heat
sink are shown in Figures 19 and 20. These curves can
be used to determine the appropriate airflow for a given
set of operating conditions. For example, if the unit with
airflow along its length dissipates 20 W of heat, the
correct airflow in a 40 °C environment is 1.0 m/s
(200 ft./min.).
8-1315 (C)
Figure 19.Convection Power Derating with No Heat
Sink; Airflow Along Width; Transverse
Orientation
8-1314 (C)
Figure 20.Convection Power Derating with No Heat
Sink; Airflow Along Length; Longitudinal
Orientation
Heat Transfer with Heat Sinks
The power modules have through-threaded, M3 x 0.5
mounting holes, which enable heat sinks or cold plates
to be attached to the module. The mounting torque
must not exceed 0.56 N-m (5 in.-lb.). For a screw
attachment from the pin side, the recommended hole
size on the customer’s PWB around the mounting
holes is 0.130 ± 0.005 inches. If a larger hole is used,
the mounting torque from the pin side must not exceed
0.25 N-m (2.2 in.-lb.).
Thermal derating with heat sinks is expressed by using
the overall thermal resistance of the module. Total
module thermal resistance (θca) is defined as the max-
imum case temperature rise (∆TC, max) divided by the
module power dissipation (PD):
The location to measure case temperature (TC) is
shown in Figure 18. Case-to-ambient thermal resis-
tance vs. airflow for various heat sink configurations is
shown in Figures 21 and 22. these curves were
obtained by experimental testing of heat sinks, which
are offered in the product catalog.
0 10203040 100
0
40
60
70
LOCAL AMBIENT TEMPERATURE, TA (˚C)
POWER DISSIPATION, PD (W)
30
20
10
9080706050
50
4.0 m/s (800 ft./min.)
3.5 m/s (700 ft./min.)
3.0 m/s (600 ft./min.)
2.5 m/s (500 ft./min.)
2.0 m/s (400 ft./min.)
1.5 m/s (300 ft./min.)
1.0 m/s (200 ft./min.)
0.5 m/s (100 ft./min.)
0.1 m/s (20 ft./min.) NAT. CONV.
0 10203040 100
0
40
60
70
LOCAL AMBIENT TEMPERATURE, TA (˚C)
POWER DISSIPATION, PD (W)
30
20
10
9080706050
4.0 m/s (800 ft./min.)
3.5 m/s (700 ft./min.)
3.0 m/s (600 ft./min.)
2.5 m/s (500 ft./min.)
2.0 m/s (400 ft./min.)
1.5 m/s (300 ft./min.)
1.0 m/s (200 ft./min.)
0.5 m/s (100 ft./min.)
50
0.1 m/s (20 ft./min.) NAT. CONV.
θca ∆TC, max
PD
-------------------- TCTA
–()
PD
------------------------
==
1414 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Thermal Considerations (continued)
Heat Transfer with Heat Sinks (continued)
8-1321 (C)
Figure 21.Case-to-Ambient Thermal Resistance
Curves; Transverse Orientation
8-1320 (C)
Figure 22.Case-to-Ambient Thermal Resistance
Curves; Longitudinal Orientation
These measured resistances are from heat transfer
from the sides and bottom of the module as well as the
top side with the attached heat sink; therefore, the
case-to-ambient thermal resistances shown are gener-
ally lower than the resistance of the heat sink by itself.
The module used to collect the data in Figures 21 and
22 had a thermal-conductive dry pad between the case
and the heat sink to minimize contact resistance.
To choose a heat sink, determine the power dissipated
as heat by the unit for the particular application.
Figure 23 shows typical heat dissipation for a range of
output currents and three voltages for the FC250B1.
8-1662 (C)
Figure 23.FC250B1Power Dissipation vs. Output
Current at 25 °C
0.0
0.5
3.0
3.5
4.0
4.5
2.5
2.0
1.0
1 1/2 IN. HEAT SINK
1 IN. HEAT SINK
1/2 IN. HEAT SINK
1/4 IN. HEAT SINK
NO HEAT SINK
1.5
AIR VELOCITY, m/s (ft./min.)
0 0.5
(100)
1.0
(200)
1.5
(300)
2.0
(400)
2.5
(500)
3.0
(600)
CASE-TO-AMBIENT THERMAL
RESISTANCE, θ
CA
(˚C/W)
0 0.5
(100)
1.0
(200)
1.5
(300)
2.0
(400)
2.5
(500)
3.0
(600)
0.0
0.5
3.0
3.5
4.0
4.5
2.5
2.0
1.0
1 1/2 IN. HEAT SINK
1 IN. HEAT SINK
1/2 IN. HEAT SINK
1/4 IN. HEAT SINK
NO HEAT SINK
CASE-TO-AMBIENT THERMAL
RESISTANCE, θCA
(˚C/W)
1.5
AIR VELOCITY, m/s (ft./min.)
10
24 12
14 16 18
0
OUTPUT CURRENT, IO (A)
15
25
5
55
200 8 106
POWER DISSIPATION, PD (W)
35
20
30
50
40
45
VI = 18 V
VI = 27 V
VI = 36 V
Tyco Electronics Corp. 15
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Thermal Considerations (continued)
Heat Transfer with Heat Sinks (continued)
Example
If an 85 °C case temperature is desired, what is the
minimum airflow necessary? Assume the FC250B1
module is operating at VI = 28 V and an output current
of 20 A, maximum ambient air temperature of 40 °C,
and the heat sink is 1 inch.
Solution
Given: VI = 28 V
IO = 20 A
TA = 4 0 °C
TC = 85 °C
Heat sink = 1 inch
Determine PD by using Figure 23:
PD = 47 W
Then solve the following equation:
Use Figures 21 and 22 to determine air velocity for the
1 inch heat sink. The minimum airflow necessary for
this module depends on heat sink fin orientation and is
shown below:
■1.4 m/s (280 ft./min.) (oriented along width)
■1.8 m/s (360 ft./min.) (oriented along length)
Custom Heat Sinks
A more detailed model can be used to determine the
required thermal resistance of a heat sink to provide
necessary cooling. The total module resistance can be
separated into a resistance from case-to-sink (θcs) and
sink-to-ambient (θsa) as shown in Figure 24.
8-1304 (C)
Figure 24.Resistance from Case-to-Sink and Sink-
to-Ambient
For a managed interface using thermal grease or foils,
a value of θcs = 0.1 °C/W to 0.3 °C/W is typical. The
solution for heat sink resistance is:
This equation assumes that all dissipated power must
be shed by the heat sink. Depending on the user-
defined application environment, a more accurate
model, including heat transfer from the sides and bot-
tom of the module, can be used. This equation pro-
vides a conservative estimate for such instances.
EMC Considerations
For assistance with designing for EMC compliance,
please refer to the FLTR100V10 data sheet
(DS99-294EPS)
Layout Considerations
Copper paths must not be routed beneath the power
module mounting inserts. For additional layout guide-
lines, refer to the FLTR100V10 data sheet
(DS99-294EPS).
θca TCTA
–()
PD
-------------------------=
θca 85 40–()
47
----------------------=
θca 0.96 °C/W=
PD
TCTSTA
θcs θsa
→
θsa TCTA
–()
PD
-------------------------θcs–=
1616 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Outline Diagram
Dimensions are in millimeters and (inches).
Tolerances: x.x mm ± 0.5 mm (x.xx in. ± 0.02 in.),
x.xx mm ± 0.25 mm (x.xxx in. ± 0.010 in.)
Top View
Side View
Bottom View
8-1650 (C).a
* Side label includes Tyco logo, product designation, safety agency markings, input/output voltage and current ratings, and bar code.
116.8 (4.60)
61.0
(2.40)
13.5
(0.53)
5.1 (0.20) MIN 1.57 ± 0.05 (0.062 ± 0.002) DIA
SOLDER-PLATED BRASS,
11 PLACES
(VOUT-, VOUT+, VIN-, VIN+)
1.02 ± 0.05 (0.040 ± 0.002) DIA
SOLDER-PLATED BRASS,
9 PLACES
SIDE LABEL*
CASE
SYNC IN
ON/OFF
VI-
VI+
2.54 (0.100) TYP
VO-
VO+
SYNC OUT
SENSE-
SENSE+
TRIM
PARALLEL
CURRENT MON
PWR GOOD
5.1 (0.20)
50.8
(2.00)
30.48
(1.200)
22.86
(0.900)
12.7
(0.50)
5.08
(0.200)
10.16
(0.400) 15.24
(0.600)
20.32
(0.800)
25.40
(1.000)
30.48
(1.200)
35.56
(1.400)
66.04 (2.600)
MOUNTING INSERTS
M3 x 0.5 THROUGH,
4 PLACES
5.1 (0.20)
2.54 (0.100) TYP
106.68 (4.200)
7.62
(0.300
)
17.78
(0.700)
12.70
(0.500)
Tyco Electronics Corp. 17
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Recommended Hole Pattern
Component-side footprint.
Dimensions are in millimeters and (inches).
8-1650 (C).a
Ordering Information
Table 5. Device Codes
Input Voltage Output Voltage Output Power Device Code Comcode
28 V 12 V 250 W FC250B1 107539868
5.1 (0.20)
10.16
(0.400)
MOUNTING INSERTS
5.1 (0.20)
2.54 (0.100) TYP
2.54 (0.100) TYP
5.08
(0.200
)
15.24
(0.600)
20.32
(0.800)
25.40
(1.000)
30.48
(1.200)
35.56
(1.400)
106.68 (4.200)
66.04 (2.600)
50.8
(2.00)
30.48
(1.200)
22.86
(0.900)
17.78
(0.700)
12.70
(0.500)
12.7
(0.50)
7.62
(0.300)
CASE
SYNC IN
ON/OFF
VI-
VI+
VO-
VO+
SENSE-
SENSE+
TRIM
PARALLEL
CURRENT MON
PWR GOOD
7.62
(0.300)
7.62
(0.300)
18 Tyco Electronics Corp.
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Ordering Information (continued)
Table 6. Device Accessories
Dimension are in millimeters and (inches).
Accessory Comcode
1/4 in. transverse kit (heat sink, thermal pad, and screws) 847308335
1/4 in. logitudinal kit (heat sink, thermal pad, and screws) 847308327
1/2 in. transverse kit (heat sink, thermal pad, and screws) 847308350
1/2 in. logitudinal kit (heat sink, thermal pad, and screws) 847308343
1 in. transverse kit (heat sink, thermal pad, and screws) 847308376
1 in. logitudinal kit (heat sink, thermal pad, and screws) 847308368
1 1/2 in. transverse kit (heat sink, thermal pad, and screws) 847308392
1 1/2 in. logitudinal kit (heat sink, thermal pad, and screws) 847308384
8-2830 (C)
Figure 25.Longitudinal Heat Sink
8-2831 (C)
Figure 26.Transverse Heat Sink
1/4 IN.
1/2 IN.
1 IN.
1 1/2 IN.
60.45
115.82
(4.56)
(2.38)
1/4 IN.
1/2 IN.
1 IN.
1 1/2 IN.
115.82
(4.56)
59.94
(2.36)
Tyco Electronics Corp. 19
Data Sheet
January 2000 18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
Notes
Printed on
Recycled Paper
Data Sheet
January 2000
18 Vdc to 36 Vdc Input, 12 Vdc Output; 250 W
FC250B1 Power Module: dc-dc Converter;
World Wide Headquarters
Tyco Electronics Power Systems, Inc.
3000 Skyline Drive, Mesquite, TX 75149, USA
+1-800-526-7819 FAX: +1-888-315-5182
(Outside U.S.A.: +1-972-284-2626, FAX: +1-972-284-2900)
www.power.tycoelectronics.com
e-mail: techsupport1@tycoelectronics.com
Tyco Electronics Corporation reserves the right to make changes to the product(s) or information contained herein without notice. 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.
© 2001 Tyco Electronics Power Systems, Inc. (Mesquite, Texas) All International Rights Reserved.
Printed in U.S.A.
January 2000
DS99-322EPS (Replaces DS97-542EPS)
Europe, Middle-East and Africa Headquarters
Tyco Electronics (UK) Ltd
Tel: +44 (0) 1344 469 300, Fax: +44 (0) 1344 469 301
Central America-Latin America Headquarters
Tyco Electronics Power Systems
Tel: +54 11 4316 2866, Fax: +54 11 4312 9508
Asia-Pacific Headquarters
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Tel: +65 482 0311, Fax: 65 480 9299
