Smart Sync

GND

PTH08T250W

Track

C

I1

+

UDG-08149

V

I

Sync

TurboTrans

+Sense

V

O

-Sense

+

GND

C

O1

PRE

GND

Q

Q

CLK

CLK

D

V

CC

GND

PTH08T240W

Track

C

I2

+

V

I

Sync

TurboTrans

+Sense

R

SET2

V

O

Adj

V

O

-Sense

+

GND

C

O2

0°

180°

V

O2

f

CLK

= 2 x f

MOD

SN74LVC2G74

V

I

= 5 V

V

O1

R

SET1

V

O

Adj

AGND

PTH08T255W

The overtemperature protection is a last resort mechanism to prevent thermal stress to the regulator.

Operation at or close to the thermal shutdown temperature is not recommended and reduces the long-term

reliability of the module. Always operate the regulator within the specified safe operating area (SOA) limits for

the worst-case conditions of ambient temperature and airflow.

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

not used, this pin must be connect to GND. 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 of

240 kHz to 400 kHz.

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<10kHz) allows

the EMI filter to be designed to attenuate only the synchronization frequency. Power modules can also be

synchronized out of phase to minimize ripple current and reduce input capacitance requirements.

The PTH08T255W requires that the external synchronization frequency be present before a valid input voltage is

present or before release of the inhibit control.

Figure 14 shows a typical circuit with two modules synchronized 180° out of phase using a D flip-flop.

Figure 14. Typical Smart Sync Schematic

Copyright © 2008, Texas Instruments Incorporated

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Product Folder Link(s): PTH08T255W