VPT250-2800S Series
HIGH RELIABILITY COTS DC-DC CONVERTERS
DESCRIPTION
FEATURES
The VPT250 series of isolated COTS DC-DC
converters is a cost effective solution for many
demanding high reliability applications. A wide input
voltage range accommodates nominal 28V inputs
including avionics, mobile, ground systems, and
other applications. A high efficiency design using
synchronous rectification reduces input power
requirements and eases thermal management. Low
input and output ripple, fixed operating frequency,
and current sharing capability simplify system design
and compliance. A proven design heritage, no
optoisolators and a rugged epoxy encapsulated
package ensure long term reliability.
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
The VPT250 series is intended for harsh
environments including severe vibration, shock and
temperature cycling. Testing is to JESD22, MIL-STD810, and MIL-STD-883.
These converters are designed and manufactured in
the USA in a facility certified to ISO9001, J-STD-001
and IPC-A-610.






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High Reliability at Low Cost
Parallel Up to 5 Units With Current Sharing
Up to 250 Watts Maximum Output Power
High Efficiency, Up to 92%
Wide Input Voltage Range: 16 to 40 Volts per
MIL-STD-704 and MIL-STD-1275
High Input Transient Voltage: 50 Volts for 1 sec
Fixed Frequency
Output Voltage Trim (+10% / -20% )
Input Undervoltage Lockout
Soft Start
Indefinite Short Circuit Protection
Current Limit Protection
2000V Isolation
No Optoisolators
Wide Temperature Range, -55°C to 100°C
Six-Sided Rugged Epoxy Encapsulated
Package with Integral Metalized EMI shield fully
compatible with aqueous cleaning processes
This product may incorporate one or more of the
following U.S. patents:
5,784,266
5,790,389
5,963,438
5,999,433
6,005,780
6,084,792
6,118,673
Figure 1 - VPT250-2800S Converter
(Not to Scale)
VPT250-2800S-3.0
http://www.vptpower.com
Sales Information:
Phone: (425) 353-3010
Fax: (425) 353-4030
E-mail: vptsales@vptpower.com
1
VPT250-2800S Series
SPECIFICATIONS (TCASE = -55°C to +100°C, VIN = +28V ± 5%, Full Load, Unless Otherwise Specified)
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Continuous)
Input Voltage (Transient, 1 second)
Output Power1
Power Dissipation (Full Load, TCASE = +100°C)
Parameter
40 VDC
50 Volts
250 Watts
37 Watts
Conditions
Junction Temperature Rise to Case
Storage Temperature
Lead Solder Temperature (10 seconds)
Weight (Maximum)
VPT250-283R3S
+25°C
-55°C to +125°C
300°C
118 Grams
VPT250-2805S
Min
Typ
Max
Min
Typ
Max
16
28
40
16
28
40
Units
STATIC
Continuous
INPUT
Voltage
Transient, 1 sec
Current
Ripple Current
4
-
-
50
-
-
50
V
Inhibited
-
3.5
5
-
3.5
5
mA
No Load
-
190
350
-
190
350
mA
mAp-p
Full Load, 20Hz to 10MHz
Inhibit Pin Input
4
Inhibit Pin Open Circuit Voltage
4
-
300
500
-
500
700
0
-
1.5
0
-
1.5
V
9
11
14
9
11
14
V
5
15.1
15.5
15.9
15.1
15.5
15.9
V
4, 5
13.9
14.5
15.1
13.9
14.5
15.1
V
V
UVLO Turn On
UVLO Turn Off
OUTPUT
Voltage
VOUT
TCASE = 25°C
3.251
3.3
3.350
4.925
5
5.075
VOUT
TCASE = -55°C to +100°C
3.218
3.3
3.383
4.875
5
5.125
V
0
-
165
0
-
250
W
0
-
50
0
-
50
A
mVp-p
3
Power
Current
V
3
VOUT
6
VOUT
Full Load, 20Hz to 10MHz
-
-
150
-
-
150
Line Regulation
VOUT
VIN = 16V to 40V
-
-
20
-
-
20
mV
Load Regulation
VOUT
No Load to Full Load
-
-
50
-
-
50
mV
0
-
5
0
-
5
V
Ripple Voltage
Share Pin Voltage
4
4
Current Share Accuracy
-
5
-
-
5
-
%
85
88
-
87
90
-
%
Overload
-
-
50
-
-
50
W
Short Circuit
-
-
50
-
-
50
W
-
-
8,000
-
-
8,000
F
264
300
336
264
300
336
kHz
264
-
336
264
-
336
kHz
100
-
-
100
-
-
MΩ
-
316
-
-
316
-
kHrs
EFFICIENCY
LOAD FAULT POWER DISSIPATION
4
4
CAPACITIVE LOAD
SWITCHING FREQUENCY
SYNC FREQUENCY RANGE
VH-VL=5V
Duty Cycle = 50%
ISOLATION
2000 VDC
MTBF (MIL-HDBK-217F)
GM @ TC = 55°C
See notes next page.
VPT250-2800S-3.0
2
VPT250-2800S Series
SPECIFICATIONS (TCASE = -55°C to +100°C, VIN = +28V ± 5%, Full Load, Unless Otherwise Specified)
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Continuous)
Input Voltage (Transient, 1 second)
Output Power1
Power Dissipation (Full Load, TCASE = +100°C)
Parameter
40 VDC
50 Volts
250 Watts
37 Watts
Conditions
Junction Temperature Rise to Case
Storage Temperature
Lead Solder Temperature (10 seconds)
Weight (Maximum)
VPT250-283R3S
+25°C
-55°C to +125°C
300°C
118 Grams
VPT250-2805S
Min
Typ
Max
Min
Typ
Max
-
260
400
-
260
400
Units
DYNAMIC
Load Step Output Transient
VOUT
2
Load Step Recovery
Line Step Output Transient
4
VOUT
2, 4
Line Step Recovery
Turn On Delay
Turn On Overshoot
Notes:
VOUT
¾ Load to Full Load
VIN = 16V to 40V
VIN = 0V to 28V
mVPK
-
250
500
-
250
500
Sec
-
500
750
-
500
750
mVPK
-
300
500
-
300
500
Sec
-
5
10
-
5
10
mSec
-
0
25
-
0
25
mVPK
1.
2.
3.
4.
5.
Dependent on output voltage
Time for output voltage to settle within 1% of its nominal value
Derate linearly to 0 at 110°C
Verified by qualification testing
Typical hysteresis = 1.0V. Avoid repetitive on/off cycling (chattering) during a startup event by keeping any external
source and cable impedance at a minimum.
6. Using recommended minimum external output capacitance of 1.0uF
VPT250-2800S-3.0
3
VPT250-2800S Series
SPECIFICATIONS (TCASE = -55°C to +100°C, VIN = +28V ± 5%, Full Load, Unless Otherwise Specified)
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Continuous)
Input Voltage (Transient, 1 second)
Output Power1
Power Dissipation (Full Load, TCASE = +100°C)
Parameter
40 VDC
50 Volts
250 Watts
37 Watts
Conditions
Junction Temperature Rise to Case
Storage Temperature
Lead Solder Temperature (10 seconds)
Weight (Maximum)
VPT250-2812S
+25°C
-55°C to +125°C
300°C
118 Grams
VPT250-2815S
Min
Typ
Max
Min
Typ
Max
16
28
40
16
28
40
Units
STATIC
Continuous
INPUT
Voltage
Transient, 1 sec
Current
Ripple Current
4
-
-
50
-
-
50
V
Inhibited
-
3.5
5
-
3.5
5
mA
No Load
-
190
350
-
190
350
mA
mAp-p
Full Load, 20Hz to 10MHz
Inhibit Pin Input
4
Inhibit Pin Open Circuit Voltage
4
-
500
700
-
500
700
0
-
1.5
0
-
1.5
V
9
11
14
9
11
14
V
5
15.1
15.5
15.9
15.1
15.5
15.9
V
4, 5
13.9
14.5
15.1
13.9
14.5
15.1
V
V
UVLO Turn On
UVLO Turn Off
OUTPUT
Voltage
VOUT
TCASE = 25°C
11.82
12
12.18
14.775
15
15.225
VOUT
TCASE = -55°C to +100°C
11.7
12
12.3
14.625
15
15.375
V
0
-
250
0
-
250
W
0
-
20.83
0
-
16.67
A
mVp-p
3
Power
Current
V
3
VOUT
6
VOUT
Full Load, 20Hz to 10MHz
-
-
150
-
-
150
Line Regulation
VOUT
VIN = 16V to 40V
-
-
50
-
-
50
mV
Load Regulation
VOUT
No Load to Full Load
-
-
100
-
-
100
mV
0
-
5
0
-
5
V
Ripple Voltage
Share Pin Voltage
4
4
Current Share Accuracy
-
5
-
-
5
-
%
89
92
-
89
92
-
%
Overload
-
-
50
-
-
50
W
Short Circuit
-
-
50
-
-
50
W
-
-
1500
-
-
1500
F
264
300
336
264
300
336
kHz
264
-
336
264
-
336
kHz
100
-
-
100
-
-
MΩ
-
316
-
-
316
-
kHrs
EFFICIENCY
LOAD FAULT POWER DISSIPATION
4
4
CAPACITIVE LOAD
SWITCHING FREQUENCY
SYNC FREQUENCY RANGE
VH-VL=5V
Duty Cycle = 50%
ISOLATION
2000 VDC
MTBF (MIL-HDBK-217F)
GM @ TC = 55°C
See notes next page.
VPT250-2800S-3.0
4
VPT250-2800S Series
SPECIFICATIONS (TCASE = -55°C to +100°C, VIN = +28V ± 5%, Full Load, Unless Otherwise Specified)
ABSOLUTE MAXIMUM RATINGS
Input Voltage (Continuous)
Input Voltage (Transient, 1 second)
Output Power1
Power Dissipation (Full Load, TCASE = +100°C)
Parameter
40 VDC
50 Volts
250 Watts
37 Watts
Conditions
Junction Temperature Rise to Case
Storage Temperature
Lead Solder Temperature (10 seconds)
Weight (Maximum)
VPT250-2812S
+25°C
-55°C to +125°C
300°C
118 Grams
VPT250-2815S
Min
Typ
Max
Min
Typ
Max
-
390
700
-
390
700
Units
DYNAMIC
Load Step Output Transient
VOUT
2
Load Step Recovery
Line Step Output Transient
4
VOUT
2, 4
Line Step Recovery
Turn On Delay
Turn On Overshoot
Notes:
VOUT
¾ Load to Full Load
VIN = 16V to 40V
VIN = 0V to 28V
mVPK
-
250
500
-
250
500
Sec
-
800
1200
-
800
1200
mVPK
-
300
500
-
300
500
Sec
-
5
10
-
5
10
mSec
-
0
50
-
0
50
mVPK
1.
2.
3.
4.
5.
Dependent on output voltage
Time for output voltage to settle within 1% of its nominal value
Derate linearly to 0 at 110°C
Verified by qualification testing
Typical hysteresis = 1.0V. Avoid repetitive on/off cycling (chattering) during a startup event by keeping any external
source and cable impedance at a minimum.
6. Using recommended minimum external output capacitance of 1.0uF
VPT250-2800S-3.0
5
VPT250-2800S Series
BLOCK DIAGRAM
28V IN
+V OUT
IN COM
OUT COM
CURRENT
SENSE
UNDER
VOLTAGE
SHUTDOWN
PWM
CONTROL
PRIMARY
HOUSEKEEPING
SUPPLY
INH
SYNC
SHARE
TRIM
VOLTAGE AND
CURRENT
AMPLIFIERS
DIGITAL
ISOLATOR
+S
-S
Figure 2
CONNECTION DIAGRAM
VPTF20-28
1
28V IN
28V OUT
VPT250-2800S DC-DC CONVERTER
5
1
2
28 Vdc
+
-
CASE
4
3
4
28V IN
INH
SYNC
+V OUT
+S
TRIM
SHARE
CASE
-S
2
IN COM OUT COM
3
5
IN COM
OUT COM
11
10
9
8
1uF
Min.
LOAD
7
6
0.068uF
Min.
CASE
Figure 3
VPT250-2800S-3.0
6
VPT250-2800S Series
PARALLEL CONNECTION DIAGRAMS
VPT250-2800S DC-DC CONVERTER
EMI FILTER
1
2
28 Vdc
+
-
3
4
5
28V IN
28V OUT
28V IN
28V OUT
NC
CASE
IN COM OUT COM
IN COM OUT COM
10
1
9
2
8
3
7
4
6
5
+V OUT
28V IN
+S
INH
TRIM
11
10
9
SYNC
8
SHARE
CASE
-S
IN COM
CASE
OUT COM
LOAD
1uF
Min
7
6
CASE
VPT250-2800S DC-DC CONVERTER
1
2
3
4
+V OUT
28V IN
+S
INH
TRIM
SYNC
SHARE
CASE
-S
5
IN COM
11
10
9
8
1uF
Min
7
6
OUT COM
CASE
VPT250-2800S DC-DC CONVERTER
1
2
3
4
+V OUT
28V IN
11
10
+S
INH
TRIM
SYNC
SHARE
9
8
CASE
7
-S
5
IN COM
OUT COM
1uF
Min
6
CASE
Figure 4 – Current Sharing Parallel Connection for Multiple Converters
(SYNC connection is optional)
Note
1. Please contact VPT for VPT250-2800S Series Load Share configuration options utilizing VPT EMI Filters
VPT250-2800S-3.0
7
VPT250-2800S Series
CONNECTION DIAGRAMS
28V IN
11
+V OUT
10
+S
40.2
1
R-TRIM
10K
INH
BIAS
2
+
OPTIONAL
CAPACITOR
IN COM
(TRIM DOWN)
10k
8
TRIM
7
-S
Rt
11V
Ri
+
-
0.75V
5
R-TRIM
(TRIM UP)
40.2
6
Figure 5 –Inhibit Circuit
(Shown with optional capacitor for turn-on delay)
OUT COM
Figure 6 –Output Voltage Trim Circuit
OUTPUT VOLTAGE TRIM
The output voltage can be trimmed down by connecting a resistor between the TRIM pin and the +V OUT pin,
or can be trimmed up by connecting a resistor between the TRIM pin and the OUT COM pin as shown in
Figure 6. The maximum trim range is +10% up and –20% down. The appropriate resistor values versus the
output voltage are given in the trim table below.
VPT250-283R3S
VPT250-2805S
VPT250-2812S
VPT250-2815S
+VOUT (V)
RTRIM (Ω)
+VOUT (V)
RTRIM (Ω)
+VOUT (V)
RTRIM (Ω)
+VOUT (V)
RTRIM (Ω)
3.60
3.55
3.50
3.45
3.40
3.35
3.30
3.25
3.20
3.15
3.10
3.05
3.00
2.95
2.90
3.94k
8.92k
16.4k
28.8k
53.5k
127k
-486k
226k
140k
96.9k
71.3k
54.2k
42k
32.8k
5.5
5.4
5.3
5.2
5.1
5.0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
4.1
980
4.72k
10.9k
23.4k
60.5k
-404k
189k
118k
82.4k
61.1k
46.9k
36.8k
29.2k
23.3k
13.2
13.0
12.8
12.6
12.4
12.2
12.0
11.8
11.6
11.4
11.2
11.0
10.8
10.6
10.4
1.14k
2.39k
4.26k
7.39k
13.6k
32.4k
-548k
266k
172k
126k
97.4k
78.6k
65.3k
55.2k
16.50
16.25
16.00
15.75
15.50
15.25
15.00
14.75
14.50
14.25
14.00
13.75
13.50
13.25
13.00
686
1.69k
3.19k
5.7k
10.7k
25.9k
-552k
270k
175k
128k
99.5k
80.6k
67k
56.9k
2.85
2.80
2.75
2.70
2.65
25.7k
20.1k
15.4k
11.5k
8.26k
4.0
18.5k
10.2
10.0
9.8
9.6
47.4k
41.1k
36k
31.8k
12.75
12.50
12.25
12.00
49k
42.6k
37.5k
33.2k
VPT250-2800S-3.0
8
VPT250-2800S Series
96
96
94
94
92
92
90
90
88
88
Efficiency (%)
Efficiency (%)
EFFICIENCY PERFORMANCE CURVES (TCASE = 25°C, Full Load, Unless Otherwise Specified)
86
84
82
80
84
82
80
78
Input Voltage:
78
Input Voltage:
76
16 V
76
16 V
74
28 V
74
28 V
40 V
72
40 V
72
70
70
0
50
100
150
Output Power (W)
200
250
0
50
100
150
Output Power (W)
200
Figure 7: VPT250-283R3S
Figure 8: VPT250-2805S
Efficiency (%) vs. Output Power (W)
Efficiency (%) vs. Output Power (W)
96
96
94
94
92
92
90
90
88
88
Efficiency (%)
Efficiency (%)
86
86
84
82
80
250
86
84
82
80
78
Input Voltage:
78
Input Voltage:
76
16 V
76
16 V
74
28 V
74
28 V
72
40 V
72
40 V
70
70
0
50
100
150
Output Power (W)
200
250
0
50
100
150
Output Power (W)
200
Figure 9: VPT250-2812S
Figure 10 – VPT250-2815S
Efficiency (%) vs. Output Power (W)
Efficiency (%) vs. Output Power (W)
VPT250-2800S-3.0
250
9
VPT250-2800S Series
EMI PERFORMANCE CURVES
100
100
90
90
80
80
70
70
Signal (dBuV)
Signal (dBuV)
(TCASE = 25°C, VIN = +28V ± 5%, Full Load, Unless Otherwise Specified)
60
50
40
60
50
40
30
30
20
20
10
10
0
0
0.01
0.10
1.00
10.00
0.01
0.10
1.00
Scan Frequency (MHz)
Scan Frequency (MHz)
MIL-STD-461 D, E & F Limit
MIL-STD-461 D, E & F Limit
Figure 11: VPT250-2800S without EMI Filter
10.00
Figure 12: VPT250-2800S with VPTF20-28 EMI Filter
80
80
70
70
60
60
50
50
Signal (dBuA)
Signal (dBuA)
Note: Minimum 0.068uF capacitor required as shown in Figure 3
40
30
20
10
40
30
20
10
0
0
-10
-10
-20
-20
0.1
1.0
10.0
100.0
0.1
1.0
Scan Frequency (MHz)
DO-160 Cat. B
DO-160 Cat. L, M & H
Figure 13: VPT250-2800S without EMI Filter
10.0
100.0
Scan Frequency (MHz)
DO-160 Cat. B
DO-160 Cat. L, M & H
Figure 14 – VPT250-2800S with VPTF20-28 EMI Filter
Note: Minimum 0.068uF capacitor required as shown in Figure 3
VPT250-2800S-3.0
10
VPT250-2800S Series
PACKAGE SPECIFICATIONS
0.410in 10.41mm MAX
0.220in±0.015
5.59mm±0.38
2.000in 50.80mm
1.700in 43.18mm
5
6
1.300in 33.02mm
4
7
1.100in 27.94mm
1.000in 25.40mm
8
3
0.900in 22.86mm
9
0.700in 17.78mm
2
10
0.300in 7.62mm
1
11
0in 0mm
4X PIN
0.079in±0.002
2mm±0.05
7X PIN
0.039in±0.002
1mm±0.05
TOP VIEW
SIDE VIEW
Pin
2.330in 59.18mm MAX
2.000in 50.80mm
BASEPLATE
SURFACE
2.450in 62.23mm MAX
1.900in 48.26mm
4X
0.004
0.150in +-0.003
+0.10
3.80mm - 0.08
Function
1
28VIN
2
INHIBIT
3
SYNC
4
CASE
5
INCOM
6
OUTCOM
7
-SENSE
8
SHARE
9
TRIM
10
+SENSE
11
+VOUT
BOTTOM VIEW
Figure 15 – Package and Pinout
(Dimensional Limits are ±0.005” Unless Otherwise Stated)
Package Notes
1. Case temperature is measured on the center of the baseplate surface
2. Materials: Body - epoxy with integral metalized EMI shield
Pins - copper, gold over nickel plating
3. Mounting holes are not threaded. Recommended fastener is 4-40
4. This package is highly resistant to chemical, solvent and salt environments and is fully compatible with high
volume manufacturing processes including wave solder, cleaning solvents, high pressure sprays and aqueous
wash processes
VPT250-2800S-3.0
11
VPT250-2800S Series
PACKAGE PIN DESCRIPTION
Pin
Function
Description
1
28VIN
Positive Input Voltage Connection
2
INHIBIT
This is an open collector input. Logic Low = Disabled Output. Connect the inhibit
pin to input common to disable the output. Unconnected, open collector or open
drain = Enabled Output.
3
SYNC
Input Synchronization Signal. TTL squarewave, 5Vpp, 30 - 70% duty cycle,
internally capacitively coupled.
4
CASE
Case Connection
5
INCOM
Input Return Connection
6
OUTCOM
Output Return Connection
7
-SENSE
Output Return Remote Sense. Compensate for up to 1.0V total drop (positive and
return).
8
SHARE
Current Share Connection
9
TRIM
Trim Output Voltage to +10%, -20% of Nominal Value. Leave open if not used.
10
+SENSE
Positive Output Voltage Remote Sense. Compensate for up to 1.0V total drop
(positive and return).
11
+VOUT
Positive Output Voltage Connection
100% ENVIRONMENTAL SCREENING
Screening
Condition
Internal Visual
IPC-A-610, Class 3
Stabilization Bake
MIL-STD-883, Method 1008, Condition B, 125°C, 24 hours
Temperature Cycling
MIL-STD-883, Method 1010, Condition B, -55°C to +125°C, 10 Cycles
Burn-In
96 hours at +100°C
Final Electrical
100% at 25°C
External Visual
Internal Procedure
VPT250-2800S-3.0
12
VPT250-2800S Series
ORDERING INFORMATION
VPT250-
28
05
S
1
2
3
4
(1)
(2)
(3)
(4)
Product Series
Nominal Input Voltage
Output Voltage
Number of Outputs
VPT250-
28
28 Volts
3R3
05
12
15
3.3 Volts
5 Volts
12 Volts
15 Volts
S
Single
CONTACT INFORMATION
To request a quotation or place orders please contact your sales representative or the VPT Inc. Sales
Department at:
Phone:
Fax:
E-mail:
(425) 353-3010
(425) 353-4030
vptsales@vptpower.com
All information contained in this datasheet is believed to be accurate, however, no responsibility is assumed for possible errors
or omissions. The products or specifications contained herein are subject to change without notice. VPT, its logo and tagline
are registered trademarks in the U.S. Patent and Trademark Office.
VPT250-2800S-3.0
13