1)This manual is valid for the following Model and associated serial numbers:
MODELSERIAL NO.REV. NO.
2)A Change Page may be included at the end of the manual. All applicable changes and
revision number changes are documented with reference to the equipment serial numbers. Before using this Instruction Manual, check your equipment serial number to identify
your model. If in doubt, contact your nearest Kepco Representative, or the Kepco Documentation Office in New York, (718) 461-7000, requesting the correct revision for your particular model and serial number.
3)The contents of this manual are protected by copyright. Reproduction of any part can be
made only with the specific written permission of Kepco, Inc.
6.0 General Specifications ............................................................................................................................ 3
9.0 Current Limit............................................................................................................................................ 4
17.0 Output Voltage Trim ................................................................................................................................ 6
18.5 Use of Graphs.................................................................................................................................... 8
20.0 General Features .................................................................................................................................. 10
5 General Specifications ............................................................................................................................... 3
SCOPE OF MANUAL: This instruction brief contains information for the installation and operation of the
Kepco KFD 150 Watt DC to DC Converter. For further operating and service information for the KFD 150
Watt DC to DC Converter contact your Kepco Representative directly, or write to Kepco, Inc., 131-38 Sanford Avenue, Flushing, New York 11352 U.S.A.
2.0 DESCRIPTION:
The Kepco KFD 150 Watt DC to DC Converter has a nominal 36-72 Vdc input and a 5 Volt DC output nominal voltage. The DC to DC Converter is a low-dissipative stabilizer, using pulse-width modulation to control
the output. The unit features input/output isolation and remote ON/OFF. Remote ON/OFF is accomplished
by an isolated TTL level signal that may use either mechanical or solid state closure. The output voltage
may be adjusted with a trimmer terminal located in the upper right hand corner of the unit (see Figure 3,
top view). The unit is guaranteed for one year when operated within the specifications given herein.
3.0 ABSOLUTE MAXIMUM RATINGS:
The DC to DC Converter described in this manual is rated for continuous operation when used in an ambient temperature range of 0° to 71°C. Within this range the unit will operate according to the specifications
listed below, provided they are not subject to stress. The unit will function with degraded reliability and life
if operated at the extreme ends of the temperature range, at -40° to 0°C, or 71°C to 90°C. Specifications
Do Not Apply Throughout The Entire Operating Range (-40° To 90°C)
STRESSES IN EXCESS OF THE MAXIMUM RATINGS can cause permanent damage to the unit. THESE
are absolute stress ratings only. Functional operation of the unit is not implied at these or any other conditions in excess of those in the following tables.
The following specifications apply to the power supply model listed below:
MODELINPUTOUTPUT
KFD 6-25-60W36-72 VOLTS DC5 VDC 30A
4.0 INPUT SPECIFICATIONS (SEE TABLE 1):
TABLE 1. INPUT SPECIFICATIONS
ParameterDescription
Nominal Input Voltage48-60Vdc
Input Voltage Range36-72 Vdc
Input Current Maximum*6A (V
Efficiency: V
See Figure 1
Switching Frequency100KHz
Circuit TypeForward Converter
Input Reflected Ripple Current
(peak to peak,5Hz to 20 MHz, 12
TA=25°C, see Figure 2)
Input Ripple Rejection (120Hz)60 dB typical
Inrush Current (I
*THE KFD MODULE IS NOT INTERNALLY FUSED, AN INPUT LINE FUSE MUST ALWAYS BE USED
=48 Volts, Io= I
I
2
t)1.0 A2s maximum
;TA=20°C
o, max.
µ
H source impedance,
=0 to 72 Volts)
I
80% typical
82% minimum
20 mA peak to Peak
KFD 6-25-60/060801
1
5.0 OUTPUT SPECIFICATIONS (SEE TABLES 2, 3, AND 4)
µ
TABLE 2. OUTPUT SPECIFICATIONS FOR THE KFD UNIT
ParameterDescription
Output Voltage Nominal5V
Output Current Nominal30A
Output Power Maximum150W
1
Ripple
Noise, 5Hz to 20Mhz100 mV p-p max.
Output Current Minimum1.0A
Output Current Maximum30.0A
1
At less than minimum load the DC to DC converter may exceed its output ripple specification
35mV RMS max.
TABLE 3. DYNAMIC RESPONSE FOR THE KFD UNIT
CharacteristicSpecification
∆
Io
----------
Dynamic Response to Load
Change
TypicalUnit
Peak Deviation150mV
Settling Time (Vo< 10% of
Peak Deviation)
300
∆T
From Io = 50% to 75% I
and from Io=50% to 25% I
VI=48 Volts, TA=25°C
1 A
------------ --=
10
S
o,max
o,max.
µ
S
2
KFD 6-25-60/060801
TABLE 4. OUTPUT SPECIFICATIONS
Parameter
Output Voltage (Over All Operating Input Voltage,
Resistive Load, And Temperature Conditions)
Output Voltage Setpoint (V
TA=25°C.
Unit Operating In Parallel Or Parallel Pin Shorted
To Sense (-) Pin (See Figure 3)
=48 volts, Io= Iomax,
I
Specification
MINMAXTYP UNIT
4.756.25Vdc
4.9
5.1
500
Vdc
Parallel Pin Open
Output Short Circuit Current51.040.5A
Output Current Limit Inception30.939.0A
Output Current30.0A
Output Regulation : Line Vi= 36 to 72 Volts
Load Io= 1.0A to I
Temperature -TA =0°C° to 90°C
max
o
4.9
02%0.05%%
6.25
0.4%0.2%%
5050mV
5.00
6.0 GENERAL SPECIFICATIONS (SEE TABLE 5)
TABLE 5. GENERAL SPECIFICATIONS
ParameterSpecification
Case Temperature (min-max)
Isolation Resistance10M Ohms Minimum
Isolation Capacitance1700 pF Typical
I/O Isolation Voltage500 Vdc Maximum
Calculated MTBF
(at 80% of I
Dimensions
Weight7.0 OZS (198.45 Grams) Maximum
Cover MaterialNon- Conductive Material
o
,
max ,
T = 40°C)
Operating: 0° to 90°C
Storage: -40°C to 125°C
920000 Hours
0.66(16.8) X 4.8(121.9) X 2.5(63.5)
See Mechanical Outline Drawing, Figure 3
Vdc
KFD 6-25-60/060801
3
7.0 FEATURE SPECIFICATIONS (SEE TABLES 6 AND 7)
TABLE 6. REMOTE ON/OFF
State
ON/.OFF CURRENTLogic Low1.0ma
ON/OFF VOLTAGELogic Low1.2V
Logic High
I
ON/OFF
Open Collector Switch Specifications
Leakage Current During Logic High
(V
ON/OFF
Output Low Voltage During Logic Low
I
ON/OFF
Turn On Time (Io =80%I
of V
NOTES: 1. Remote On/Off (0 Volts <V1< 72 Volts, Open Collector Or Equivalent, Signal
=18V)
=1mA
omax.
o,set)
Referenced to -V1 Terminal)
2. Logic Low-module ON; Logic High-module OFF
=0
; Vo within ±1%
TABLE 7. FEATURE SPECIFICATIONS
ParameterSpecification
Output Overvoltage Clamp, 6.6 Volts Minimum7.0 8.0 V
Output Voltage Sense Range1.0V
Output Voltage Trim Range, 5.0 Volts Minimum7.0
Parallel Operation Load Sharing
Specification
TypMaxUn it
18V
50
1.2V
510 ms
TypMa xUn it
20%
I
o,max,
µΑ
8.0 OUTPUT OVERVOLTAGE CLAMP
The KFD output voltage is controlled by the primary regulation loop. The control circuitry for the overvoltage clamp is independent of the KFD DC to DC Converter primary regulation loop. A secondary output
voltage control is provided by the overvoltage clamp circuitry, thereby reducing the possibility of output
overvoltage. This is realized by having the set point of the overvoltage clamp designed to be higher than
the set point of the primary loop.
9.0 CURRENT LIMIT
The KFD DC to DC Converter is protected against output overload by internal current limiting. This mode
of operation can be maintained for an unlimited time duration provided that the case temperature is maintained at or below 90°C. At the very point of current limit inception the DC to DC converter shifts from a
voltage control to a current control mode.
10.0 REMOTE ON/OFF
The DC to DC Converter can be remotely controlled via a switch (that the user must supply) across the
ON/OFF terminal and the -V
maximum I
ON/OFF
(when the module is ON) is 1 mA. The switch should be able to sink 1 mA when it is at a
I terminal
logic low voltage. At logic high the maximum V
(V
). At logic low V
ON/OFF
ON/OFF
ON/OFF
=0 to 1.2 Volts, the unit is ON; and the
of the KFD unit is 18 Volts. The maximum allowable
leakage current of the switch (at logic high) is then 50µa.
4
KFD 6-25-60/060801
A jumper across the ON/OFF terminal and the -VI terminal can be used to override the Remote ON/OFF
(see Figure 4). Either a user-supplied switch or the override jumper should be wired into the circuit via individual PWB current paths not common to the
KFD terminals, across the common connection point and the Remote ON/OFF point. This connection will
prevent noise from falsely triggering the Remote ON/OFF.
11.0 OUTPUT VOLTAGE REVERSAL
current path. Connect the switch or jumper wire at the
-VI
CAUTION
Do not apply a reverse polarity voltage across the KFD output terminals. Such an
application will forward bias an internal diode of the Power Module and damage
the KFD unit.
12.0 ISOLATION
The KFD output is fully isolated from the input. The KFD DC to DC Converter is encapsulated in nonconductive cases that mount on PC boards. The module is rated to full load at 71°C in a natural convection
environment (without a heat sink or external filter).
13.0 PARALLEL OPERATION
The Power Module can be configured for parallel operation with forced load sharing, to provide for redundant operation or to satisfy additional power requirements. For a typical redundant operation, Schottky
diodes or equivalent should be used to protect against a short circuit condition. The forward voltage drops
across the diodes do not affect the set point voltage applied to the load because of the remote sensing
compensation. If multiple units are used to develop combined power, in excess of the rated maximum (to
satisfy additional power requirements), the Schottky diodes are not required.
14.0 FORCED LOAD SHARING
To implement forced load sharing, the following connections must be made at the pins of the KFD unit. In
addition to that the wiring configuration must be arranged in a way that is compatible with good noise
immunity
a) The parallel pins of all the units connected in parallel must be connected together. The paths of
these connections must be as direct as possible.
b) All Remote Sense pins must be connected to the D.C to D.C. Converter bus at the same point. Connect
all Remote Sense (+) terminals to the (+) side of the power bus at the same point, and all Remote Sense
(-) terminals to the (-) side of the power bus at the same point.
NOTE
CLOSE PROXIMITY AND SHORT CONNECTING WIRES ARE NECESSARY
FOR GOOD NOISE IMMUNITY
KFD 6-25-60/060801
5
15.0 REMOTE SENSE
Remote Sense pins are provided to minimize the effects of distribution losses that come about from regulating the output voltage at the remote sense terminals. The KFD output voltage specifications refer to
measurements taken at the Remote Sense terminals during parallel operation, or with the parallel pin
shorted to the Sense (-) pin. The voltage between the Remote Sense pins and the KFD output terminals
must not exceed the output voltage Sense range given in the KFD specifications. The combination of output set point adjustment range and output voltage Sense range given in the Feature Specifications Table,
Table 7 cannot exceed 16.5 Volts between the Vo (+) and Vo (-) terminals.
16.0 SAFETY CONSIDERATIONS
For Safety Standard approval, the system that the Power Module is used in, must satisfy the following condition:
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 22.2-950, EN 60 950.
For the Converter output to satisfy the requirements of the Safety Extra Low Voltage Standard (SELV), one
of the following conditions must be valid for the D.C. input:
The Converter input meets all requirements of SELV, or
The Converter must be provided with reinforced insulation to protect against hazardous voltages, including
the A.C. mains; and comply with SELV reliability tests.
17.0 OUTPUT VOLTAGE TRIM
The output trim feature provides for the capability of increasing or decreasing the output voltage setpoint of
the Power Module. This can be accomplished by using an external resistor between the TRIM pin and
either the SENSE (+) or SENSE (-) pin (see Figures 7 and 8).
With an external resistor connected between the TRIM pin and SENSE (–) pin (R
age setpoint (V
) increases to the higher voltage defined in this equation:
o, TRIM
1.25
R
TRIM UP–
----------- ------------- ------------- ----
=
V
,
o
TRIM
5620
5–
TRIM-UP
With an external resistor connected between the TRIM pin and the SENSE (+) pin (R
put voltage setpoint (Vo,
) decrease to the lower voltage defined by this equation:
TRIM
R
TRIM DOWN–
V
o TRIM,
----------- ------------- ------------- -------
5
–
1.25–
V
o TRIM,
5620()=
), the output volt-
TRIM-DOWN
), the out-
The Combination of output set point adjustment range and output voltage Sense range, given in the Feature Specifications Table 7, cannot exceed 16.5 Volts across the Vo (+) and Vo (-) terminals (see Figures
6, 7 and 8).
6
KFD 6-25-60/060801
18.0 THERMAL CONSIDERATIONS
To ensure reliable operation of the KFD unit, thermal management is important. Heat dissipated by the unit
is conducted to the case, and subsequently convected to the surrounding air. Convection cooling can be
improved by mounting a heat sink to the top of the unit. Six threaded holes, No. 4-40 [0.18 inches deep
(46mm)] are provided for this purpose. A dry pad or thermal compound should be used to minimize thermal
resistance between the case and the heat sink. The case temperature should not exceed 90 degrees C.
18.1 CASE TEMPERATURE
Proper cooling for the KFD D.C. to D.C. Converter can be verified by measuring the case temperature of
the module. It is measured on the top surface of the unit at a sensing point---3 inches (76mm) from the left
edge of the power module, and 0.7 inches (18mm) from the top edge of the unit. The case temperature
must not exceed 95°C while the unit is operating in the final system configuration. After the module has
reached thermal equilibrium, the measurement can be made with a thermocouple or surface probe. If a
heat sink is mounted to the case, make the measurement at the base of the heat sink as close as possible
to the heat sensing point. The contact resistance between the mounting surface and the heat sink must be
taken into account when making this measurement.
Maintaining the operating case temperature (Tc) within the specified range keeps internal component temperatures within their specifications. That in turn helps keep the expected mean time between failure
(MTBF) from falling below the specified rating. The KFD Power Module is designed with temperature resistant components such as ceramic capacitors that do not degrade during prolong exposure to high temperatures, as do aluminum electrolytic capacitors.
18.2 FORCED CONVECTION
The discussion that follows can be applied to all high powered KFD board mounted power modules in the
4.8in (121.9mm) x 2.5in (63.5mm) x 0.5in (12.7mm) package.
Increasing the air flow over the module improves cooling. In that regard Figure 11 shows the power derating (P
) versus local ambient temperature (TA) at air flows, from natural convection to 800 ft./min. (4.1 m/
D
s). The curves in this Figure were obtained from measurements made in a free stream of air approaching
a vertically oriented module on a printed wiring board, positioned in a rectangular passage. The Figure
can be used to determine the appropriate air flow for a given set of operating conditions.
For example, at P
=20W and TA=40°C, an air flow of 200 ft./min. (1.0 m/s) is sufficient to keep the module
D
within its ratings.
18.3 HEAT SINK MODELS
Figures 9 and 10 show a number of standard heat sinks that are available for the KFD Power Module,
labeled with their respective thermal resistances for natural convection. The heat sinks mount to the top
surface of the power module using No. 4-40 hardware, torqued to 5 in.lbs. To minimize contact resistance
and temperature drops, use a thermally conductive dry pad or thermal grease between the case and heat
sink.
18.4 NATURAL CONVECTION
The plots in Figures 12 and 13 represent power derating for a power module in natural convection when
attached to various heat sinks (these include designs with fins oriented along the length and designs with
KFD 6-25-60/060801
7
the fins oriented along the width). Natural convection is the air flow produced when air in contact with a
hot surface is heated. An open environment is required with no external forces moving the air. The Figures
apply when the power module is the only source of heat present in the system.
18.5 USE OF GRAPHS
First determine the amount of power that is to be dissipated as heat, as well as the ambient operating temperature. Plot the data on the graph, and note the intersection point; the point indicates the appropriate
heat sink to use. For instance, if P
=20 W and Ta=30°C, a 0.5 inch (12.7mm) heat sink with fins oriented
D
along the width, would keep the module within its operating temperature rating
18.6 THERMAL MODELS
The curves in Figure 14 are plots of thermal resistance against air velocity, for various types of heat sinks;
with fins oriented along the width and with fins oriented along the length. The plots are determined experimentally without a heat sink and with the heat sinks illustrated in Figures 9 and 10 . The highest values on
the curves represent natural convection. In a system with free flowing air and other heat sources, there
may be additional air flow.
The following two examples illustrate how the curves can be used to determine thermal performance under
various air flow and heat sink configurations.
Example 1: To determine the air flow required to maintain T
(case temperature)=95°C for the KFD
c,max
150W D.C. to D.C. Converter (the KFD 6-25-60W) without a heat sink, consider the following:
The KFD DC to DC Converter (150W) operates at Io=30 Amps and T
=50° without a heat sink. The power
A
dissipated by the unit can be determined from the difference between the input power and output power
and the efficiency of the converter. It can be noted that the unit has a power dissipation of 37.5 watts. The
thermal resistance that is necessary to maintain a 95°C case temperature is determined from the equations that follow:
The total thermal resistance of the unit is defined as the maximum case temperature rise divided by the
power dissipation of the module:
ϑ = Total thermal resistance
∆Τc max = Maximum case temperature rise
From Figure 14 the required air flow necessary to maintain a 95°C case temperature then is greater than
500 ft./min. (2.5 m/s)
Example 2: How to determine the case temperature for a specific operating environment. Say for example, that only an air flow of 150 ft./min is available and it is required to determine the case temperature
8
KFD 6-25-60/060801
using a one half inch fin heat sink oriented along the length. Consider the following:
For an air flow of 150 ft./min. using the same D.C. to D.C. Converter as in the last example and with a 0.5
inch heat sink with fins oriented along the length, refer to the thermal resistance plot. From Figure 14 the
thermal resistance is 1.3°C/W.
∆T
∆
T
=
C
37.5 1.3() 48.75 °C==
C
θ)(
P
D
After the delta change in case temperature is calculated, the actual case temperature is determined by the
following:
∆T
T
C
+()50°C48.75 C+()98.75
T
A
C
°
C===
18.7 DETAILED THERMAL MODEL
The thermal resistance previously includes heat transfer by conduction, convection, and radiation, from the
entire module to the surrounding environment. Typically the KFD power module is soldered to a vertically
oriented printed wiring board. Most of the heat transfer is by convection and radiation from the top mounting surface of the module. Significant amounts of heat are also removed by convection from the sides of
the module, by conduction by the printed wiring board, and by convection off of the opposite side of the
printed wiring board
18.8 RADIATION HEAT TRANSFER
Radiation is not dependent upon the air flow over the power module, but on the temperature difference
between the module and the surrounding environment. For a particular KFD power module, θ
due to
R
radiation can be determined experimentally. For the KFD high power modules operating at Tc=95°C and
Ta =2 5° C, θ
(Radiation Resistance) =15°C/W
R
18.9 HORIZONTAL ORIENTATION
In some applications the power module is operated in natural convection and oriented horizontally. In that
situation θ
TOTAL
=4.8°C/W for the overall module thermal resistance (including the base plate resistance).
19.0 FUSING CONSIDERATIONS
CAUTION
THE KFD MODULE IS NOT INTERNALLY FUSED; AN INPUT
LINE FUSE MUST ALWAYS BE USED
The encapsulated KFD Power Module can be used in a stand alone operation, or as an integrated part of
a complex power architecture. To achieve maximum safety and system protection always use an input line
fuse. To aid in the proper fuse selection for a given application, information on inrush energy and maximum
current is provided in the KFD specifications. It is also recommended to refer to the fuse manufacturer's
KFD 6-25-60/060801
9
data for additional data.
20.0 GENERAL FEATURES
Among the general features of the KFD D.C. to D.C. Converter are the ones listed below:
•Low Profile: 0.5 inch
•Internal EMI Filter
•Complete Input And Output Filtering
•Input To Output Isolation
•Short Circuit Protection
•Output Overvoltage Clamp: 6.6 Volts minimum
•High Efficiency: 80% Typical
•Fabricated with Surface Mount Technology
•Compatible for printed circuit board mounting
•Compatible for heat sink
•Meets FCC Requirements for Telecommunications
21.0 APPLICATIONS
Among the possible applications of the KFD D.C. to D.C. Converter are the following:
•Redundant Power Architecture
•Distributed Power Architecture
•Telecommunications
•Private Branch Exchange
10
KFD 6-25-60/060801
NOTE:WHEN PLACING THE POWER MODULE INTO A PRINTED CIRCUIT BOARD
SOCKET, USE KELVIN CONNECTIONS AT THE POWER MODULE INPUT
AND OUTPUT TERMINALS TO AVOID MEASUREMENT ERRORS DUE TO
SOCKET CONTACT RESISTANCE.
FIGURE 1 TEST SETUP FOR OUTPUT VOLTAGE AND EFFICIENCY
MEASUREMENTS FOR THE DC TO DC CONVERTER
KFD 6-25-60/060801
11
NOTE:AT THE INPUT THE REFLECTED RIPPLE IS MEASURED WITH A SIMU-
LATED SOURCE IMPEDANCE OF 12µH; THE CAPACITOR, C
, OFFSETS
s
POSSIBLE BATTERY IMPEDANCE. CURRENT IS MEASURED AT THE
INPUT OF THE POWER MODULE.
FIGURE 2 TEST SETUP FOR THE INPUT REFLECTED RIPPLE FOR
THE SINGLE OUTPUT KFD DC TO DC CONVERTER.
12
KFD 6-25-60/060801
FIGURE 3 MECHANICAL OUTLINE DRAWING OF THE SINGLE OUT-
PUT KFD DC TO DC CONVERTER
KFD 6-25-60/060801
13
FIGURE 4 REMOTE ON/OFF WIRING CONFIGURATION FOR THE
SINGLE OUTPUT KFD DC TO DC CONVERTER
14
3040491
KFD 6-25-60/060801
FIGURE 5 WIRING CONFIGURATION FOR REDUNDANT PARALLEL
OPERATION OF THE KFD DC TO DC CONVERTER
KFD 6-25-60/060801
15
FIGURE 6 CIRCUIT CONFIGURATION FOR SINGLE KFD DC TO DC CONVERTER
REMOTE SENSE OPERATION
16
KFD 6-25-60/060801
FIGURE 7 (TOP) KFD DC TO DC CONVERTER CIRCUIT CONFIGURA-
TION FOR R
Trim Down
, TO DECREASE VOLTAGE SETPOINT
FIGURE 8 (BOTTOM) KFD DC TO DC CONVERTER CIRCUIT CONFIG-
URATION FOR R
, TO INCREASE VOLTAGE SETPOINT
Trim Up
KFD 6-25-60/060801
17
FIGURE 9 HEAT SINKS FOR VERTICAL ORIENTATION - KEPCO
MODEL KFD-02 AND THE KEPCO MODEL KFD-04
18
KFD 6-25-60/060801
FIGURE 10 HEAT SINKS FOR HORIZONTAL ORIENTATION - KEPCO
MODEL KFD-01 AND THE KEPCO MODEL KFD-03
KFD 6-25-60/060801
19
NOTE:THE GRAPHS ARE PLOTTED AS A FUNCTION OF THE AIR FLOW WITHOUT THE
USE OF A HEAT SINK (FOR THE KFD POWER MODULE COOLING)
FIGURE 11 FORCED CONVECTION DERATING, POWER DISSIPATION