UCC3588

Features:

• 5-Bit Digital-to-Analog Converter (DAC) supports Intel Pentium II
• Microprocessor VID Codes
• Compatible with 5V or 12V Systems
• 1% Output Voltage Accuracy Guaranteed
• Drives 2 N-Channel MOSFETs
• Programmable Frequency to 800kHz
• Power Good OV / UV / OVP Voltage Monitor
• Undervoltage Lockout and Softstart Functions
• Short Circuit Protection
• Low Impedance MOSFET Drivers
• Chip Disable


Pinout





Specifications

Supply Voltage V_CC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15V
Gate Drive Current, 50% Duty Cycle. . . . . . . . . . . . . . . . . . 1A
Input Voltage, V_SENSE, V_FB, SS, COMMAND, COMP. . . . . . . . 5V
Input Voltage, D0, D1, D2, D3, D4 . . . . . . . . . . . . . . . .  . . . 6V
Input Current, RT, COMP . . . . . . . . . . . . . . . . . . . . . . . . . 5mA

Currents are positive into, negative out of the specified terminal. Consult Packaging Section of Databook for thermal limitations and considerations of packages. All voltages are referenced to GND.


Description

The UCC3588 synchronous step-down (Buck) regulator provides accurate high efficiency power conversion. Using few external components, the UCC1588 converts 5V to an adjustable output ranging from 3.5VDC to 2.1VDC in 100mV steps and 2.05VDC to 1.3VDC in 50mV steps with 1% DC system accuracy. A high level of integration and novel design allow this 16-pin controller to provide a complete control solution for today's demanding microcontroller power requirements. Typical applications include on board or VRM based power conversion for Intel Pentium II microprocessors, as well as other processors from a variety of manufacturers. High efficiency is obtained through the use of synchronous rectification.

The softstart function provides a controlled ramp up of the system output voltage. Overcurrent circuitry detects a hard (or soft) short on the system output voltage and invokes a timed softstart/shutdown cycle to reduce the PWM controller on time to 5%.

The oscillator frequency is externally programmed with RT and operates over a range of 50kHz to 800kHz. The gate drivers are low impedance totem pole output stages capable of driving large external MOSFETs. Cross conduction is eliminated by fixed delay times between turn off and turn on of the external high side and synchronous MOSFETs. The chip includes undervoltage lockout circuitry which assures the correct logic states at the outputs during power up and power down.