10/08/02
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1
ADVANCED ANALOG
HIGH RELIABILITY
DC/DC CONVERTERS
AHF2815T SERIES
Description
n
16 to 40 VDC Input Range (28 VDC Nominal)
n
5V,
15 Volt Output
n
Infinite Short Circuit and Overload
Protection
n
8 Watts Output Power
n
Fast Loop Response for Superior Transient
Characteristics
n
Operating Temperature Range from -55C to
+125C Available
n
Popular Industry Standard Pin-Out
n
Resistance Seam Welded Case for Superior
Long Term Hermeticity
n
Efficiency Up to 75%
n
Shutdown from External Signal
n
400,000 Hour MTBF at 85%
Features
AHF
28V Input, Triple Output
The AHF2815T Series of DC/DC converters provide 8
watts of power and an extended temperature range for
use in military and industrial applications. Designed to
the nominal input requirements of MIL-STD-704, these
devices have nominal 28VDC inputs with +5V and 15V
triple outputs to satisfy a wide range of requirements.
The basic circuit utilizes a pulse width modulated, feed
forward topology at a nominal switching frequency of
550KHz. Input to output isolation is achieved through
the use of transformers in the forward and feedback
circuits.
The proprietary magnetic feedback circuit provides for
an extremely wide bandwidth control loop with a high
phase margin. The closed loop frequency response of
this converter family extends to approximately 50KHz,
resulting in superior line and load transient character-
istics. This feedback method is also inherently tem-
perature and radiation insensitive. This gives the AHF
Series an important advantage over converters that
incorporate opto-couplers in their design.
Manufactured in a facility qualified to MIL-PRF-38534,
these converters are available in four screening grades
to satisfy a wide range of requirements. The CH grade
is fully compliant to the requirements of MIL-PRF-38534
for class H. The HB grade is processed and screened
to the class H requirement, but may not necessarily
meet all of the other MIL-PRF-38534 requirements, e.g.,
element evaluation and Periodic Inspection (P.I.) not
required. Both grades are tested to meet the complete
group "A" test specification over the full military tem-
perature range without output power deration. Two
grades with more limited screening are also available
for use in less demanding applications. Variations in
electrical, mechanical and screening can be accom-
modated. Contact Advanced Analog for special re-
quirements.
n
Constant Switching Frequency
(550KHz Nominal)
PD - 94542
2
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AHF2815T Series
Specifications
For Notes to Specifications, refer to page 3
T
CASE
= -55C to +125C, V
IN
= +28V
5% unless otherwise specified
7
n
TYPICAL CHARACTERISTICS
Temperature Range
7
Operating -55
C to +125
C case
Storage -65
C to +135
C
Isolation 100 megaohms at 500 volts DC
Weight 35 grams
Conversion frequency 550 kHz
Test Symbol Conditions
-55C
Tc
+125C
Vin = 28 Vdc 5%, C
L
= 0
unless otherwise specified
7
AHF2815T
Limits
Unit
Min
Max
STATIC
CHARACTERISTICS
Output voltage
1
V
OUT
I
OUT
= 0 (main)
TC = 25
C
Over Temp
4.95
4.90
5.05
5.10
V
V
Current
1,2,3
Ripple Voltage
1,4
Power
1,2,3
I
OUT
V
RIP
P
OUT
I
OUT
= 0 (dual)
1
V
IN
= 16, 28, and 40 Vdc (main)
V
IN
= 16, 28, and 40 Vdc (dual)
V
IN
= 16, 28, and 40 Vdc
BW = DC to 2 MHz (main)
V
IN
= 16, 28, and 40 VDC
BW = DC to 2 MHz (dual)
V
IN
= 16, 28, and 40 Vdc (main)
(+dual)
(-dual)
(total)
TC = 25
C
Over Temp
14.50
14.35
120
0.0
5
1.5
1.5
8
15.50
15.65
1200
66.7
60
80
V
V
mA
mA
mV p-p
mV p-p
W
W
W
W
REGULATION
Line
1,3
Load
1,3
VR
LINE
VR
LOAD
V
IN
= 16, 28, and 40 VDC
I
OUT
= 120, 600,1200 mA (main)
I
OUT
= 0,
33.4,
66.7 mA (dual)
V
IN
= 16, 28, and 40 VDC
I
OUT
= 120, 600, 1200mA (main)
I
OUT
= 0,
33.4,
66.7 mA (dual)
T
C
= 25
C
Over Temp
25
35
75
50
75
mV
mV
mV
mV
mV
Input current
I
IN
I
OUT
= 0, inhibit (pin 1)
tied to input return (pin 7)
15
mA
I
OUT
= 0, inhibit (pin 1) = open
50
mA
Ripple current
4
I
RIP
I
OUT
= 1200mA (main)
I
OUT
=
66.7 mA (dual)
BW = DC to 2MHz
50
mA
p-p
Efficiency E
FF
P
OUT
= Full load
T
C
=
25
C
68 %
T
C
=
25
C
Isolation
ISO
Input to output or any pin
to case (except pin 6) at 500
V dc Tc = +25C
T
C
=
25
C
100 M
Load fault power
dissipation
3
P
D
Overload, T
C
=
25
C
5
Short Circuit, T
C
=
25
C
T
C
=
25
C
8
6
W
W
Switching frequency
F
S
500
600
kHz
Inhibit Open
Circuit Voltage
V
OI
9 13 V
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3
AHF2815T Series
Notes to Specifications
1.
Tested at each output.
2.
Parameter guaranteed by line and load regulation tests.
3.
At least 20 percent of the total output power should be taken from the (+5 volt) main output.
4.
Bandwidth guaranteed by design. Tested for 20 KHz to 2 MHz.
5.
An overload is that condition with a load in excess of the rated load but less than that necessary to trigger the
short circuit protection and is the condition of maximum power dissipation.
6.
Above 125
C case temperature, derate output power linearly to 0 at 135
C case.
7. T
CASE
= -55
C to 85
C for non screened grade.
Application Information
Connecting the inhibit input (Pin 1) to input common (Pin 7)
will cause the converter to shut down. It is recommended
that the inhibit pin be driven by an open collector device
capable of sinking at least 400 A of current. The open
circuit voltage of the inhibit input is 11.5 1 VDC.
Inhibit Function
Thermal Management
Assuming that there is no forced air flow, the package tem-
perature rise above ambient (
T) may be calculated using
the following expression:
T = 80 A
0.7
p
0.85
(
C)
where A = the effective surface area in square inhes(in-
cluding heat sink if used), P = power dissipation in watts.
The total surface area of the AHF package is 4.9 square
inches. If a worse case full load efficiency of 75% is as-
sumed, then the case temperature rise can be calculated
as follows:
W
Eff
P
P
OUT
66
.
2
1
78
.
1
8
1
1
=
-
=
-
=
T = 80 (4.9)
-0.7
(2.66)
0.85
= 60.4
C
Hence, if T
AMBIENT
= +25
C, the DC/DC converter case
temperature will be approximately 85
C if no heat sink or
air flow is provided.
AHF2815T Block Diagram
2 + V out
P uls e W idth
M odulator
P rim ary
H ouse keep ing
S upply
E M I
F ilter
8
1
7
+ Inp ut
E nable
In put
R eturn
E rror
A m p &
R ef
F B
C S
D riv e
4
-V out
6
C ase
5
3
+ V out
R eturn
F ilter
&
R egulator
4
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AHF2815T Series
AHF2815T Pin Designation
AHF2815T Case Outlines
1 .4 5 0
(3 6 .8 3 )
0 .2 6 0
(6 .6 0 0 )
0 .0 3 0 d ia ., 8 p in s
(0 .7 6 0 )
0 .8 0 0
(2 0 .3 2 )
4
7
5
8
6
1
2
3
1 .1 2 0
(2 8 .4 5 )
0 .0 9 0 R T y p
(2 .2 9 0 )
0 .3 3 0
(8 .3 8 0 )
M A X
1 .1 0 5
(2 8 .0 7 )
0 .9 0 5
(2 2 .9 9 )
0 .7 0 5
(1 7 .9 1 )
0 .5 0 5
(1 2 .8 3 )
0 .2 0 5
(5 .2 1 )
Standard
Flanged
AH F 28 15 T F / C H
M o d e l
In p u t V o lta g e
2 8 = 2 8 V N o m in a l
O u tp u t V o lta g e
1 5 = 5 V ,1 5 V
O u tp u ts
T = T rip le
S c re e n in g
, E S , H B , C H
P a c ka g e O p tio n s
F = F la n g e
O m it fo r S ta n d a rd
Part Numbering
Pin No.
Designation
1 Enable
Input
2 +Dual
Output
3
Output
Return
4 -Dual
Output
5 +5V
Output
6 Case
Ground
7 Input
Return
8 Positive
Input
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5
AHF2815T Series
Available Standard Military Drawing (SMD) Cross Reference
WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, Tel: (310) 322 3331
ADVANCED ANALOG: 2270 Martin Av., Santa Clara, California 95050, Tel: (408) 727-0500
Visit us at www.irf.com for sales contact information.
Data and specifications subject to change without notice. 10/02
Available Screening Levels and Process Variations for AHF2815T Series
*
Per Commercial Standards
Requirement MIL-STD-883
Method
No
Suffix
ES
Suffix
HB
Suffix
CH
Suffix
Temperature
Range
-20 to +85
C -55
C to +125
C -55
C to +125
C -55
C to +125
C
Element
Evaluation
MIL-PRF-38534
Internal Visual
2017
Yes Yes Yes
Temperature
Cycle
1010
Cond B
Cond C
Cond C
Constant
Acceleration
2001
500g
Cond A
Cond A
Burn-in 1015
48hrs @ 85
C
48hrs @ 125
C
160hrs @ 125
C
160hrs @ 125
C
Final Electrical
(Group A)
MIL-PRF-
38534
Specification
25
C 25
C
-55, +25, +125
C
-55, +25, +125
C
Seal, Fine &
Gross
1014
Cond A
Cond A, C
Cond A, C
Cond A, C
External
Visual
2009
Yes Yes Yes
Standardized
Military Drawing
Pin
Vendor
CAGE
Code
Vendor
Similar
Pin
5962-9462301 52467
AHF2815T
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