SC1144

• Allows use of small surface mount components
• Ultra fast transient recovery time
• Wide, High frequency operating range
• Selectable 2, 3, 4 phase operation
• Floating feedback ground for remote sensing
• Precision load current sharing
• Selectable internal or external clock
• Soft start, Over current protection
• 5-bit DAC programmable output
• programmable clock, 200Khz-2Mhz per phase

• High end servers and workstations
• High current/Ultra-fast transient microprocessors
• Voltage Regulator Modules

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 SC1144 is externally initialized using a soft-start capacitor allowing the controller to "wake-up" without overshoot, thus protecting the low voltage microprocessorloads. The output drive voltage to the power MOSFETs is programmable to minimize switching losses in the drive circuitry.

The floating feedback ground SC1144 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 hysteresis and overcurrent protection.