PD - 94541
AHF28XX SERIES
ADVANCED ANALOG
HYBRID-HIGH RELIABILITY
DC/DC CONVERTERS
Description
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.
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.
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.
28V Input, Single and Dual Output
AHF
Features
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
n
Wideband Control Loop for
Superior Transient Characterstics
n
No Derating for -55°C to +125°C Opertation
n
Constant Switching Frequency
(550KHz Nominal)
Extensive computer simulation using complex
modeling enables rapid design modification to
be provided. Contact Advanced Analog with spe-
cific requirements.
www.irf.com
1
10/08/02
AHF28XX Series
Specifications
n
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Soldering Temperature
Case Temperature
-0.5V to 50V
300°C for 10 seconds
Operating -55°C to +125°C
Storage -65°C to +135°C
AHF2805S
Table I. Electrical Performance Characteristics
Conditions
-55°C
≤
Tc
≤
+125°C
Vin = 28 Vdc ±5%, C
L
= 0
Unless otherwise specified
I
OUT
= 0
V
IN
= 16, 28, and 40 V dc
V
IN
= 16, 28, and 40 V dc,
B.W. = 20 Hz to 2MHz
V
IN
= 16, 28, and 40 V dc,
Iout = 0, 500, and 1000 mA
V
IN
= 16, 28, and 40 V dc,
I
OUT
= 0, 500, and 1000 mA
I
OUT
= 0, inhibit (pin 1)
tied to input return (pin 7)
I
OUT
= 0,
inhibit (pin 1) = open
I
OUT
= 1000mA
B.W. = 20 Hz to 2MHz
I
OUT
= 1000mA
Input to output or any pin
To case (except pin 6) at
500V dc Tc = +25°C
No effect on dc
performance, Tc = +25°C
Limits
Group A
Subgroups
Device
Types
Unit
Min
Max
Test
Symbol
Output voltage
V
OUT
I
OUT
V
RIP
VR
LINE
VR
LOAD
I
IN
1
2,3
1,2,3
1,2,3
01
4.95
4.90
5.05
5.10
2400
60
V
Output current
1
Output ripple
voltage
2
Line regulation
01
01
mA
mV p-p
1,2,3
01
25
mV
Load regulation
1,2,3
01
50
mV
Input current
1,2,3
01
12
mA
30
Input ripple current
2
I
RIP
E
FF
ISO
1,2,3
01
50
mA p-p
Efficiency
1
2,3
1
01
76
74
100
%
Isolation
01
MΩ
Capacitive load
3,4
C
L
4
01
500
µF
Power dissipation
load fault
Switching
frequency
P
D
Overload
5
Short circuit
I
OUT
= 1000mA
1
1,2,3
4,5,6
01
01
01
500
6
2
600
W
F
S
kHz
For Notes to Specifications, refer to page 3
2
www.irf.com
AHF28XX Series
Table I. Electrical Performance Characteristics -
continued
Test
Symbol
Conditions
-55°C
≤
Tc
≤
+125°C
Vin = 28 Vdc ±5%, C
L
= 0
unless otherwise specified
1200 mA to/from 2400mA
Limits
Group A
Subgroups
Device
Types
AHF2805S
Unit
Min
Max
Output response to
step transient load
changes
6
VO
TLOAD
4,5,6
01
-300
+300
mV pk
0 mA to/from 1200mA
4,5,6
-500
+500
mV pk
Recovery time step
transient load
changes
6.7
TT
LOAD
1200 mA to/from 2400mA
0 mA to 1200 mA
500 mA to 0 mA
Input step 16 V to/from
40 V dc, I
OUT
= 2400mA
4, 8
Input step 16 V to/from 40Vdc
I
OUT
= 2400mA
4, 7, 8
I
OUT
= 0 and 2400mA
I
OUT
= 0 and 2400mA
9
4,5,6
4,5,6
4,5,6
4,5,6
01
70
1200
8
500
µs
ms
ms
mV pk
Output response to
transient step line
changes
Recovery time
transient step line
changes
Turn on overshoot
Turn on delay
VO
TLINE
01
TT
LINE
4,5,6
01
800
µs
VTon
OS
Ton
D
Tr
LF
4,5,6
4,5,6
01
01
600
20
mV pk
ms
Load fault
recovery
4,9
Weight
4,5,6
01
20
ms
35
grams
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 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.
www.irf.com
3
AHF28XX Series
Specifications
n
ABSOLUTE MAXIMUM RATINGS
Input Voltage
Soldering Temperature
Case Temperature
-0.5V to 50V
300°C for 10 seconds
Operating -55°C to +125°C
Storage -65°C to +135°C
AHF2812S
Table II. Electrical Performance Characteristics
Test
Symbol
Conditions
-55°C
≤Tc ≤
+125°C
Vin = 28 Vdc ±5%, C
L
= 0
Unless otherwise specified
I
OUT
= 0
Group A
Subgroups
Device
Types
Limits
Min
1
2,3
1,2,3
1,2,3
01
11.88
11.76
Max
12.12
12.24
1000
60
V
Unit
Output voltage
V
OUT
Output current
1
Output ripple
voltage
2
Line regulation
I
OUT
V
RIP
VR
LINE
VR
LOAD
I
IN
V
IN
= 16, 28, and 40 V dc
V
IN
= 16, 28, and 40 V dc,
B.W. = 20 Hz to 2MHz
V
IN
= 16, 28, and 40 V dc,
Iout = 0, 500, and 1000 mA
V
IN
= 16, 28, and 40 V dc,
I
OUT
= 0, 500, and 1000 mA
I
OUT
= 0, inhibit (pin 1)
tied to input return (pin 7)
I
OUT
= 0,
inhibit (pin 1) = open
I
OUT
= 1000mA
B.W. = 20 Hz to 2MHz
I
OUT
= 1000mA
01
01
mA
mV p-p
1,2,3
01
50
mV
Load regulation
1,2,3
01
50
mV
Input current
1,2,3
01
12
mA
50
Input ripple current
2
I
RIP
1,2,3
01
50
mA p-p
Efficiency
E
FF
1
2,3
1
01
78
75
100
%
Isolation
ISO
Input to output or any pin
to case (except pin 6) at
500V dc Tc = +25°C
No effect on dc
performance, Tc = +25°C
Overload
5
Short circuit
01
MΩ
Capacitive load
3,4
C
L
P
D
4
01
500
µF
Power dissipation
load fault
1
1,2,3
01
01
6
2
W
Switching
frequency
F
S
I
OUT
= 1000mA
4,5,6
01
500
600
kHz
For Notes to Specifications, refer to page 5
4
www.irf.com
AHF28XX Series
Table II. Electrical Performance Characteristics -
continued
Test
Symbol
Conditions
-55°C
≤
Tc
≤
+125°C
Vin = 28 Vdc ±5%, C
L
= 0
unless otherwise specified
50 mA to/from 1000mA
0 mA to/from 500mA
Group A
Subgroups
Device
Types
Min
Limits
Max
AHF2812S
Unit
Output response
to step transient
load changes
6
VO
TLOAD
4
5,6
4
5,6
4,5,6
4,5,6
4,5,6
4,5,6
01
-300
-450
-500
-750
+300
+450
+500
+750
100
1500
10
mV pk
Recovery time
step transient
load changes
6,7
TT
LOAD
50 mA to/from 1000mA
0 mA to 500 mA
500 mA to 0 mA
01
µs
ms
mV pk
Output response
to transient step
line changes
Recovery time
transient step
line changes
Turn on
overshoot
Turn on delay
VO
TLINE
Input step 16 V to/from
40 V dc, I
OUT
=1000mA
4, 8
Input step 16 V to/from 40Vdc
I
OUT
=1000mA
4, 7, 8
I
OUT
= 0 and 1000mA
I
OUT
= 0 and 1000mA
9
01
1500
TT
LINE
4,5,6
01
800
µs
VTon
OS
Ton
D
Tr
LF
4,5,6
01
600
mV pk
4,5,6
01
20
ms
Load fault
recovery
4,9
Weight
4,5,6
01
20
ms
35
grams
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.
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5
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