11/20/02

www.irf.com

1

ADVANCED ANALOG

HYBRID-HIGH RELIABILITY

DC/DC CONVERTERS

AHV28XX SERIES

Description

n 80 Transient Input (100 msec max.)

n 50 VDC Input (Continous)

n 16 to 40 VDC Input Range

n Single, Dual and Triple Outputs

n 15 Watts Output Power

(No Temperature Derating)

n Low Input / Output Noise

n Full Military Temperature Range

n Wideband PWM Control Loop

n Magnetic Feedback

n Low Profile Hermetic Package (0.405”)

n Short Circuit and Overload Protection

n Constant Switching Frequency (500KHz)

n True Hermetic Package (Parallel Seam

Welded, Ceramic Pin Feedthru)

Features

AHV

28V Input, Single, Dual and Triple Output

The AHV Series of DC/DC converters are designed to

replace the AHE/ATO family of converters in applica-

tions requiring compliance to MIL-STD-704A through

E, in particular the input surge requirement of 80 volts

specified to withstand transient input voltage of 80 volts.

No input voltage or output power derating is necessary

over the full military temperature range.

These converters are packaged in an extremely rug-

ged, low profile package that meets all requirements of

MIL-STD-883 and MIL-PRF-38534. Parallel seam weld

sealing and the use of ceramic pin feedthru seals as-

sure long term hermeticity after exposure to extended

temperature cycling.

The basic circuit is a push-pull forward topology using

power MOSFET switches. The nominal switching fre-

quency is 500KHz. A unique current injection circuit

assures current balancing in the power switches. All

AHV series converters use a single stage LC input filter

to attenuate input ripple current. A low power 11.5volt

series regulator provides power to an epitaxial CMOS

custom pulse width modulator integrated circuit. This

single integrated circuit provides all PWM primary cir-

cuit functions. Power is transferred from primary to sec-

ondary through a ferrite core power transformer. An

error voltage signal is generated by comparing a highly

stable reference voltage with the converter output volt-

age and drives the PWM through a unique wideband

magnetic feedback circuit. This proprietary feedback

circuit provides an extremely wide bandwidth, high gain

control loop, with high phase margin. The feedback

control loop gain is insensitive to temperature, radia-

tion, aging, and variations in manufacturing. The trans-

fer function of the feedback circuit is a function of the

feedback transformer turns ratio which cannot change

when subjected to environmental extremes.

The CH grade is fully compliant to the require-

ments 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., el-

ement evaluation and Periodic Inspection (P.I.)

not required. Both grades are tested to meet the

complete group “A” test specification over the full

military temperature range without output power

deration. Two grades with more limited screen-

ing are also available for use in less demanding

applications. Variations in electrical, mechanical

and screening can be accommodated. Contact

Advanced Analog for special requirements.

Manufactured in a facility fully qualified to MIL-PRF-

38534, these converters are available in four screen-

ing grades to satisfy a wide range of requirements.

PD - 94583