SC1144

PROGRAMMABLE, HIGH PERFORMANCE MULTI-PHASE, PWM CONTROLLER Preliminary - August 24, 1999 SC1144 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1144 is a high performance, multi-phase (PWM) controller designed for high power microprocessors requiring ultra fast transient response, such as ® the Pentium ll and beyond. Utilizing a novel and unique design, the controller distributes the output load across (up to) four converter channels by digitally phase shifting the PWM outputs. This approach greatly reduces the stress and heat on the output stage components while lowering input ripple current by as much as 80%. Accurate current sharing among the four phases is achieved by precision design techniques and trimming of critical elements. The high speed transconductance error amplifier is externally initialized using a soft-start capacitor allowing the controller to “wake-up” without overshoot, thus protecting the low voltage microprocessor loads. The output drive voltage to the power MOSFETs is programmable to minimize switching losses in the drive circuitry. The floating feedback ground allows remote sense capability. The output voltage is digitally programmable by means of a 5 bit DAC. A single resistor programs the master clock frequency (8MHz max) or the controller may be synchronized using an external oscillator. The number of operating phases is programmed independently of the external clock. The parts features under-voltage lock-out with h...