10/08/02
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1
ADVANCED ANALOG
HYBRID-HIGH RELIABILITY
DC/DC CONVERTERS
AHF28XX SERIES
Description
n
16 to 40 VDC Input Range (28 VDC Nominal)
n
Single and Dual Outputs
n
12 Watts Output Power
n
22.8 W/in3 Power Density
n
Low Input / Output Noise
(50mA/60mVp-p max. respectively)
n
Indefinite Short Circuit and Overload
Protection
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Wideband Control Loop for
Superior Transient Characterstics
Features
AHF
28V Input, Single and Dual Output
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.
n
Constant Switching Frequency
(550KHz Nominal)
The AHF Series of DC/DC converters feature single or
dual outputs over the full military temperature range.
No derating in output power is required, making them
suitable for use in rugged military applications. The low
profile, small outline package is ideally suited to the
tight board space requirements of many industrial and
aerospace applications. Designed for nominal 28Vdc
inputs, this family of converters will meet the require-
ments of MIL-STD-704D. The basic circuit utilizes a
pulse width modulated, feed-forward topology at a nomi-
nal switching frequency of 550KHz. Input to output iso-
lation is achieved through the use of transformers in
the forward and feedback circuits.
These converters are manufactured in a facility certi-
fied to MIL-PRF-38534. All processes used to manu-
facture these converters have been qualified to enable
Advanced Analog to deliver compliant devices. Four
screening grades are available to satisfy a wide range
of requirements. The CH grade converters are fully com-
pliant to MIL-PRF-38534 class H. The HB grade con-
verters are processed to full MIL-PRF-38534 screen-
ing but do not have class H element evaluation as re-
quired by MIL-PRF-38534. Two grades are fully tested
and operate the full military temperature range without
derating of output power. Industrial and commercial
grades are also available. Variations are electrical,
mechanical and screening can be accommodated.
n
No Derating for -55C to +125C Opertation
Extensive computer simulation using complex
modeling enables rapid design modification to
be provided. Contact Advanced Analog with spe-
cific requirements.
PD - 94541
2
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AHF28XX Series
Specifications
For Notes to Specifications, refer to page 3
Table I. Electrical Performance Characteristics
AHF2805S
n
ABSOLUTE MAXIMUM RATINGS
Input Voltage -0.5V to 50V
Soldering Temperature 300C for 10 seconds
Case Temperature Operating -55C to +125C
Storage -65C to +135C
Limits
Test
Symbol
Conditions
-55C
Tc
+125C
Vin = 28 Vdc 5%, C
L
= 0
Unless otherwise specified
Group A
Subgroups
Device
Types
Min
Max
Unit
Output voltage
V
OUT
I
OUT
= 0
1
01
4.95
5.05
V
2,3
4.90
5.10
Output current
1
I
OUT
V
IN
= 16, 28, and 40 V dc
1,2,3
01
2400
mA
Output ripple
voltage
2
V
RIP
V
IN
= 16, 28, and 40 V dc,
B.W. = 20 Hz to 2MHz
1,2,3
01
60
mV p-p
Line regulation
VR
LINE
V
IN
= 16, 28, and 40 V dc,
Iout = 0, 500, and 1000 mA
1,2,3
01
25
mV
Load regulation
VR
LOAD
V
IN
= 16, 28, and 40 V dc,
I
OUT
= 0, 500, and 1000 mA
1,2,3
01
50
mV
Input current
I
IN
I
OUT
= 0, inhibit (pin 1)
tied to input return (pin 7)
1,2,3
01
12
mA
I
OUT
= 0,
inhibit (pin 1) = open
30
Input ripple current
2
I
RIP
I
OUT
= 1000mA
B.W. = 20 Hz to 2MHz
1,2,3
01
50
mA p-p
Efficiency
E
FF
I
OUT
= 1000mA
1
01
76
%
2,3
74
Isolation
ISO
Input to output or any pin
To case (except pin 6) at
500V dc Tc = +25C
1
01
100
M
Capacitive load
3,4
C
L
No effect on dc
performance, Tc = +25C
4
01
500
F
Overload
5
1
01
6
Power dissipation
load fault
P
D
Short circuit
1,2,3
01
2
W
Switching
frequency
F
S
I
OUT
= 1000mA
4,5,6
01
500
600
kHz
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3
AHF28XX Series
Table I. Electrical Performance Characteristics -
continued
Notes to Specifications
AHF2805S
1. Parameter guaranteed by line and load regulation tests.
2. Bandwidth guaranteed by design. Tested for 20 kHz to 2 MHz.
3. Capacitive load may be any value from 0 to the maximum limit without compromising dc performance.
A capacitive in excess of the maximum limit will not disturb loop stability but may interfere with the
operation of the load fault detection circuitry, appearing as a short circuit during turn-on.
4. Parameter shall be tested as part of design characterization and after design or process changes.
Thereafter, parameters shall be guaranteed to the limits specified in Table I.
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. Load step transition time between 2 and 10 microseconds.
7. Recovery time is measured from the initiation of the transient to where V
OUT
has returned to within 1
percent of V
OUT
at 50 percent load.
8. Input step transition time between 2 and 10 microseconds.
9. Turn-on delay time measurement is for either a step application of power at the input or the removal of
ground signal from the inhibit pin (pin 1) while power is applied to the input is unlimited.
Limits
Test
Symbol
Conditions
-55C
Tc
+125C
Vin = 28 Vdc 5%, C
L
= 0
unless otherwise specified
Group A
Subgroups
Device
Types
Min
Max
Unit
Output response to
step transient load
changes
6
VO
TLOAD
1200 mA to/from 2400mA
4,5,6
01
-300
+300
mV pk
0 mA to/from 1200mA
4,5,6
-500
+500
mV pk
1200 mA to/from 2400mA
4,5,6
01
70
s
0 mA to 1200 mA
4,5,6
1200
ms
Recovery time step
transient load
changes
6.7
TT
LOAD
500 mA to 0 mA
4,5,6
8
ms
Output response to
transient step line
changes
VO
TLINE
Input step 16 V to/from
40 V dc, I
OUT
= 2400mA
4, 8
4,5,6
01
500
mV pk
Recovery time
transient step line
changes
TT
LINE
Input step 16 V to/from 40Vdc
I
OUT
= 2400mA
4, 7, 8
4,5,6
01
800
s
Turn on overshoot
VTon
OS
I
OUT
= 0 and 2400mA
4,5,6
01
600
mV pk
Turn on delay
Ton
D
I
OUT
= 0 and 2400mA
9
4,5,6
01
20
ms
Load fault
recovery
4,9
Tr
LF
4,5,6
01
20
ms
Weight
35
grams
4
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AHF28XX Series
Specifications
AHF2812S
Table II. Electrical Performance Characteristics
For Notes to Specifications, refer to page 5
n
ABSOLUTE MAXIMUM RATINGS
Input Voltage -0.5V to 50V
Soldering Temperature 300C for 10 seconds
Case Temperature Operating -55C to +125C
Storage -65C to +135C
Limits
Test
Symbol
Conditions
-55C
Tc
+125C
Vin = 28 Vdc 5%, C
L
= 0
Unless otherwise specified
Group A
Subgroups
Device
Types
Min
Max
Unit
Output voltage
V
OUT
I
OUT
= 0
1
01
11.88
12.12
V
2,3
11.76
12.24
Output current
1
I
OUT
V
IN
= 16, 28, and 40 V dc
1,2,3
01
1000
mA
Output ripple
voltage
2
V
RIP
V
IN
= 16, 28, and 40 V dc,
B.W. = 20 Hz to 2MHz
1,2,3
01
60
mV p-p
Line regulation
VR
LINE
V
IN
= 16, 28, and 40 V dc,
Iout = 0, 500, and 1000 mA
1,2,3
01
50
mV
Load regulation
VR
LOAD
V
IN
= 16, 28, and 40 V dc,
I
OUT
= 0, 500, and 1000 mA
1,2,3
01
50
mV
Input current
I
IN
I
OUT
= 0, inhibit (pin 1)
tied to input return (pin 7)
1,2,3
01
12
mA
I
OUT
= 0,
inhibit (pin 1) = open
50
Input ripple current
2
I
RIP
I
OUT
= 1000mA
B.W. = 20 Hz to 2MHz
1,2,3
01
50
mA p-p
1
78
Efficiency
E
FF
I
OUT
= 1000mA
2,3
01
75
%
Isolation
ISO
Input to output or any pin
to case (except pin 6) at
500V dc Tc = +25C
1
01
100
M
Capacitive load
3,4
C
L
No effect on dc
performance, Tc = +25C
4
01
500
F
Overload
5
1
01
6
Power dissipation
load fault
P
D
Short circuit
1,2,3
01
2
W
Switching
frequency
F
S
I
OUT
= 1000mA
4,5,6
01
500
600
kHz
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5
AHF28XX Series
Table II. Electrical Performance Characteristics -
continued
AHF2812S
Notes to Specifications
1. Parameter guaranteed by line and load regulation tests.
2. Bandwidth guaranteed by design. Tested for 20 kHz to 2 MHz.
3. Capacitive load may be any value from 0 to the maximum limit without compromising dc performance.
A capacitive in excess of the maximum limit will not disturb loop stability but may interfere with the
operation of the load fault detection circuitry, appearing as a short circuit during turn-on.
4. Parameter shall be tested as part of design characterization and after design or process changes.
Thereafter, parameters shall be guaranteed to the limits specified in Table II.
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. Load step transition time between 2 and 10 microseconds.
7. Recovery time is measured from the initiation of the transient to where V
OUT
has returned to within 1
percent of V
OUT
at 50 percent load.
8. Input step transition time between 2 and 10 microseconds.
9. Turn-on delay time measurement is for either a step application of power at the input or the removal of
a ground signal from the inhibit pin (pin 1) while power is applied to the input is unlimited.
Limits
Test
Symbol
Conditions
-55C
Tc
+125C
Vin = 28 Vdc 5%, C
L
= 0
unless otherwise specified
Group A
Subgroups
Device
Types
Min
Max
Unit
50 mA to/from 1000mA
4
01
-300
+300
5,6
-450
+450
0 mA to/from 500mA
4
-500
+500
Output response
to step transient
load changes
6
VO
TLOAD
5,6
-750 +750
mV pk
TT
LOAD
50 mA to/from 1000mA
4,5,6
100
0 mA to 500 mA
4,5,6
1500
s
Recovery time
step transient
load changes
6,7
500 mA to 0 mA
4,5,6
01
10 ms
Output response
to transient step
line changes
VO
TLINE
Input step 16 V to/from
40 V dc, I
OUT
=1000mA
4, 8
4,5,6
01
1500
mV pk
Recovery time
transient step
line changes
TT
LINE
Input step 16 V to/from 40Vdc
I
OUT
=1000mA
4, 7, 8
4,5,6
01
800
s
Turn on
overshoot
VTon
OS
I
OUT
= 0 and 1000mA
4,5,6
01
600
mV pk
Turn on delay
Ton
D
I
OUT
= 0 and 1000mA
9
4,5,6
01
20
ms
Load fault
recovery
4,9
Tr
LF
4,5,6
01
20
ms
Weight
35
grams
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