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3

AFC461 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 switch-

ing 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 sensi-

tive systems (communications, radar or telemetry).

Advanced Analog offers an option, which provides

synchronization of multiple AHE/ATW type convert-

ers, thus eliminating this type of noise. To take ad-

vantage 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 be continue

operating should the master frequency be inter-

rupted 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 mini-

mize the possibility of radiating the 250KHz switch-

ing 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 con-

verters 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.

AFC461 Block Diagram

1

5

3

2

4

11µ F

0.2

Ω

11µ F

0.2

Ω

1800

p Fd

1800

p Fd

1N 5649A

10µ H5 µH

0.1µ F

Refer to last page for Pin Desination