ViewSonic Corporation
Confidential - Do Not Copy VP2650wb-1
26
A-6.) PWM IC (TL1451)
Fig. 2
The Tl1451AC incorporates on a single monolithic chip all the functions required in the
construction of two pulse-width modulation control circuits. Designed primarily for power
supply control, the TL1451AC contains an on-chip 2.5V regulator two error amplifiers, an
adjustable oscillator, two dead-time comparators, under-voltage lockout circuitry, and dual
common-emitter output transistor circuits. The uncommitted output transistors provide
common-emitter output capability for each controller. The internal amplifiers exhibit a
common-mode voltage range from 1.04V to 1.45V. The dead-time control comparator has no
offset unless externally altered and can provide 0% to 100% dead time. The on-chip oscillator
can be operated by modulating RT and CT. During low Vcc conditions, the under-voltage
lockout control circuit feature locks the outputs off until the internal circuitry is operational.
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