LTC1909-8

U U LTC1909-8 Wide Operating Range, No RSENSETM Step-Down DC/DC Controller with SMBus Programming FEATURES s SMBus/I2CTM Programmable Output Voltage: 1.3V to 3.5V s No Sense Resistor Required s 2% to 90% Duty Cycle at 200kHz s tON(MIN) ≤ 100ns s True Current Mode Control s Stable with Ceramic COUT s Power Good Output Voltage Monitor and 50µs Timer s Wide VIN Range: 4V to 36V (Abs Max) s Precision Resistor Divider and Reference Provide ±1.35% Output Voltage Accuracy Over Temperature s Adjustable Switching Frequency and Current Limit s Forced Continuous Control Pin s Programmable Soft-Start s Output Overvoltage Protection s Optional Short-Circuit Shutdown Timer s Available in a 28-Lead SSOP Package U APPLICATIO S s Power Supplies for DSPs, ASICs, FPGAs and CPUs s Voltage Margining DESCRIPTIO The LTC®1909-8 is a synchronous step-down switching regulator controller with a digitally programmable output voltage. The output voltage is selected from one of two 5-bit settings programmed into internal registers via a 2-wire SMBus/I2C interface. The interface features safeguards against invalid output voltages and allows the microprocessor to turn the regulator on and off. Valley current control delivers very low duty cycles without requiring a sense resistor. Operating frequency is selected by an external resistor and is compensated for variations in VIN and VOUT. Discontinuous mode operation provides high efficiency operation at light loads. A forced continuous control pin reduces...