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5

AMF28XXS Series

Block Diagram

Application Information

Inhibit Function (Enable)

EMI Filter

Device Synchronization

Notes to Specifications

Connecting the enable input (Pin 1) to input common

(Pin 7) will cause the converter to shut down. It is

recommended that the enable pin be driven by an

open collector device capable of sinking at least

400

µA of current. The open circuit voltage of the

enable input is 10 +1.0 V

An optional EMI filter is available (AFH461) that will

reduce the input ripple current to levels below the

limits imposed by MIL-STD-461 CE03.

When multiple DC/DC converters are utilized in a

single system, significant low frequency noise may

be generated due to a small difference in the

switching frequency of the converters (beat

frequency noise). Because of the low frequency

nature of this noise (typically less than 10 KHz), it is

difficult to filter out and may interfere with proper

operation of sensitive systems (communication,

radar or telemetry). Interenational Rectifier provides

synchronization of multiple AMF type converters to

match switching frequency of the converter to the

frequency of the system clock, thus eliminating this

type of noise.

1 Parameter guaranteed by line and load regulation tests.

2 Bandwidth guaranteed by design. Tested for 20Hz to 2.0MHz.

3 Capacitive load may be any value from 0 to the maximum limit without compromising dc performance. A capacitive load 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. Therefore this Parameters shall

be guaranteed to the limit specified.

5 Load step transition time between 2.0 and 10 microseconds.

6 Recovery time is measured from the initiation of the transient to where V

7 Input step transition time between 1.0 and 10 microseconds. Parameter guaranteed by design but not 100% tested.

8 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 while power is applied to the input.

3

4

+Output

Output

Return

Pulse Width

Modulator

Primary

Housekeeping

Supply

EMI

Filter

Under-Voltage

Detector

8

1

2

7

+Input

Enable

Sync

Input

Input

Return

Error

Amp &

Ref

FB

CS

Drive

6

Case