UCD7242

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SLUS962 – JANUARY 2010

PIN FUNCTIONS (continued)

UCD7242 –BUCK POWER STAGE

QFN

PIN NAME

I/O

FUNCTION

25

SRE-A

I

Synchronous Rectifier Enable input for the A-channel. High impedance digital input capable of

accepting 3.3V or 5V logic level signals used to control the synchronous rectifier switch. An appropriate

anti-cross-conduction delay is used during synchronous mode.

26

PWM -A

I

High impedance digital input capable of accepting 3.3V or 5 V logic level signals up to 2 MHz. A

Schmitt trigger input comparator desensitizes this pin from external noise. This pin controls the state of

the high side MOSFET and the low side MOSFET when SRE-A is high.

PWM = high

PWM = low

PWM = 1.65 V

SRE = high

HS = on, LS = off

HS = off, LS = on

HS = off, LS = off

SRE = low

HS = on, LS = off

HS = off, LS = off

HS = off, LS = off

27, 29, 30, 32

VIN

–

Input Voltage to the buck power stage and driver circuit

28, 31

NC

–

No internal connection. It is recommended that these pins be tied to VIN.

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