Smart Sync

GND

PTH08T220W

Track

C

330 mF

+

UDG-07132

V

I

Sync

TurboTrans

+Sense

V

O

-Sense

+

GND

C

220 mF

PRE

GND

Q

Q

CLK

CLK

D

V

CC

GND

PTH08T240F

Track

C

220 mF

+

V

I

Sync

TurboTrans

+Sense

R

SET2

V

V

O

-Sense

+

GND

C

1000 mF

0°

180°

V

f

SN74LVC2G74

V

V

R

SET1

V

Inhibit/

UVLO

Inhibit/

UVLO

PTH08T240F

Smart Sync is a feature that allows multiple power modules to be synchronized to a common frequency. Driving

the Smart Sync pins with an external oscillator set to the desired frequency, synchronizes all connected modules

to the selected frequency. The synchronization frequency can be higher or lower than the nominal switching

frequency of the modules within the range between 240 kHz and 400 kHz (see Electrical Specifications table for

frequency limits). Synchronizing modules powered from the same bus, eliminates beat frequencies reflected back

to the input supply, and also reduces EMI filtering requirements. Eliminating the low beat frequencies (usually <

10 kHz) allows the EMI filter to be designed to attenuate only the synchronization frequency. Power modules can

also be synchronized out of phase to minimize source current loading and minimize input capacitance

requirements. If unused, connect the Smart Sync pin to GND (pin 3). Figure 29 shows a standard circuit with two

modules syncronized 180° out-of-phase using a D flip-flop.

Figure 29. Smart Sync Schematic

Copyright © 2006–2008, Texas Instruments Incorporated

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