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 SEMTECH
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POWER MANAGEMENT 1 www.semtech.com SC1176/SC1176A Dual Synchronous Voltage Mode Controller with Current Sharing Circuitry Description Features Applications Revision: June 29, 2006 The SC1176 is a versatile 2 phase, synchronous, volt- age mode PWM controller that may be used in two dis- tinct ways. First, the SC1176 is ideal for applications where point of use output power exceeds any single in- put power budget. Alternatively, the SC1176 can be used as a dual switcher. The SC1176 features a temperature compensated voltage reference, over current protection with 50% fold-back and internal level-shifted, high-side drive circuitry. In current sharing configuration, the SC1176 can pro- duce a single output voltage from two separate voltage sources (which can be different voltage levels) while maintaining current sharing between the channels. Cur- rent sharing is programmable to allow loading each input supply as required by the application. In dual switcher configuration, two feedback paths are provided for independent control of the separate out- puts. The device will provide a regulated output from flexibly configured inputs (3.3V, 5V, 12V), provided 5V is present for V CC. The two switchers are 180° out of phase to minimize input and output ripple. The SC1176A has the phases of the Master and the Slave inverted. It offers a different pattern for ripple cancellation and prevents phase fold back during current limit. The two chips are pin compatible. 300kHz fixed frequency operation Soft Start and Enable function Power Good output provided Over current protection with 50% fold-back Phase-shifted switchers minimize ripple High efficiency operation, >90% Programmable output(s) as low as .9V Industrial temperature range SOIC-20 or TSSOP-20 pin Lead free package. This product is fully WEEE and RoHS compliant Two Phase, Current Sharing Controller Flexible, same or separate V IN Programmable current sharing Combined current limit with fold-back 2 phases operating opposed for ripple reduction Thermal distribution via multi-phase output Two Independent PWM Controllers Flexible, same or separate V IN Independent control for each channel Independent and separate current limit 2 phases operating opposed for ripple reduction (if same V IN used) Graphics cards DDR Memory Peripheral add-in card SSTL Termination Dual-Phase power supply Power supplies requiring two outputs |
