SC1485 Datasheet | SEMTECH

Description The SC1485 is a dual output constant on synchronousbuck PWM controller intended for use in notebook puters and other battery operated portable devices. Features include high efficiency and a fast dynamic response with no minimum on time. The excellent transient response, means that SC1485 based solutions will require less output capacitance than peting fixed frequency converters. The frequency is constant until a step in load or line voltage occurs at which time the pulse density and frequency will increase or decrease to counter the change in output or input voltage. After the transient event, the controller frequency will return to steady state operation. At light loads, Power-Save Mode enables the SC1485 to skip PWM pulses for better efficiency. Each output voltage can be independently adjusted from 0.5V to VCCA. Two frequency setting resistors set the on-time for each buck controller. The frequency can thus be tailored to minimize crosstalk. The integrated gate drivers feature adaptive shoot-through protection and soft switching. Additional Features include cycle-by-cycle current limit, digital soft-start, over-voltage and undervoltage protection, and a PGOOD output for each controller. Features Constant on-time for fast dynamic response Programmable VOUT range = 0.5 - VCCA VIN Range = 1.8V - 25V DC current sense using low-side RDS(ON) sensing or sense resistor Resistor programmable frequency Cycle-by-cycle current limit Digital soft-start Separate PSAVE option for each switcher Over-voltage/Under-voltage fault protection 10u A Typical shutdown current Low quiescent power dissipation Two PGOOD indicators 1% Reference (2% system DC accuracy) Efficiency >90% Integrated gate drivers with soft switching Separate enables 28 Lead TSSOP Industrial temperature range Applications Notebook puters CPU I/O supplies Handheld terminals and PDAs LCD monitors Network power supplies Typical Application Circuit R1 VBAT R2 9 8 22 TON2 EN/PSV2 EN/PSV1 23...