SC451

The SC451 PowerStep IV™ IC is a single chip high-performance Hysteretic PWM controller. With its integrated SmartDriver™, it powers advanced IMVP-IV™ and IMVP4+™ processors. The SC451 features extended Intel Mobile Voltage Positioning (IMVP™) to increase battery life by reducing the voltage at the processor when it is heavily loaded. It directly supports Intel's SpeedStep® processors for even longer battery life. The SC451 fully supports the Intel® Geyserville-III core voltage specification. It provides direct "deeper sleep" mode and boot voltage support. Automatic "power-save" is present to prevent negative current flow in the low-side FET during light loading conditions, saving even more power. The high side driver initially turns on with a weak drive to reduce ringing, EMI, and capacitive turn-on of the low side.

A 6-bit DAC, accurate to 0.85%, sets the output voltage reference, and implements the 0.700V to 1.708V range required by the processor. The hysteretic converter uses a comparator without an error amplifier, and therefore provides the fastest possible transient response, while avoiding the stability issues inherent to classical PWM controllers. T he DAC is externally slew rate limited to minimize transient currents and audible noise.

The SC451 operates from 5Vdc and also features soft-start, an open-drain PWRGD signal with power-good blanking, and an enable input. Programmable current limiting shuts down the SC451 after 32 current limit pulses. In addition, it comes in a space-saving MLP 6X6-28 and TSSOP-28 package. TSSOP-38 package is also available which provides a pin to pin upgrade to a dual phase solution using Semtech's dual phase controller SC450.