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3

AFV461 Series

Device Synchronization

Whenever multiple DC/DC converters are utilized in

a single system, significant low frequency noise may

be generated due to slight difference in the switching

frequencies 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 (communications, radar or telemetry).

International Rectifier offers an option, which

provides synchronization of multiple AHE/ATW type

converters, thus eliminating this type of noise. To

take advantage of this capability, the system designer

must assign one of the converters as the master.

Then, by definition, the remaining converters become

slaves and will operate at the masters’ switching

frequency. The user should be aware that the

synchronization system is fail-safe; that is, the slaves

will continue operating should the master frequency

be interrupted for any reason. The layout must be

such that the synchronization output of the master

device is connected to the synchronization input of

each slave device. It is advisable to keep this run

short to minimize the possibility of radiating the

250KHz switching frequency. A typical connection

is illustrated on the cover sheet of this document.

The appropriate converters must be ordered to take

advantage of this feature. After selecting the

converters required for the system, a ‘MSTR’ suffix

is added for the master converter part number and

an ‘SLV’ suffix is added for slave part number. See

Part Number section of the applicable converter data

sheets.

AFV461 Block Diagram

1

5

3

2

4

11µF

0.2

Ω

11µF

0.2

Ω

1800

pFd

1800

pFd

10µH

5µH

Refer to last page for Pin Designation