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5

AMF28XXD Series

Block Diagram

Application Information

Inhibit Function (Enable)

EMI Filter

Device Synchronization

Notes to Specifications

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 10KHz), it is

difficult to filter out and may interfere with proper

operation of sensitive systems (communication,

radar or telemetry). International 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.

(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. If the user chooses not to use the inhibit

function, it may be left open and the converter will

function normally. Because it is internally pulled up,

1.

Applicable to positive and negative outputs.

2.

Maximum combined output is 12W. 10.8W (max.) is available from either output (90%).

3.

Load current split equally between +V

4.

1.2W load on output under test, 1.2W to 10.8W load change on other output.

5.

Capacitive value 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.

6.

Parameter shall be tested as part of design characterization and after design or process changes. Thereafter,

parameters shall be guaranteed to the limit specified.

7.

Load step transition time between 2.0

µs and 10µs.

8.

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

50% load.

9.

Input step transient time between 1.0

µs and 10µs.

10. 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

8

1

2

7

+Input

Enable

Sync

Input

Input

Return

FB

CS

Drive

5

- Output

6

Case

Error

Amp &

Ref

Connecting the enable input (Pin 1) to input common