RC5039

The RC5039 provides complete control and protection for a DC-DC converter optimized for high-performance microprocessor applications. It is designed to drive an N-Channel MOSFET in a standard buck topology. The RC5039 integrates all of the control, output adjustment, monitoring and protection functions into a single package. The RC5039 includes a 4-Input Digital-to-Analog Converter (DAC) that adjusts the output voltage from 2.0VDC to 3.5VDC in 0.lV increments. The precision reference and voltage-mode regulator hold the selected output voltage to within over temperature and line voltage variations. The RC5039 provides simple, single feedback loop, voltage- mode control with fast transient response. It includes a 200kHz free-running triangle-wave oscillator that is adjustable from 50kHz to 1MHz. The error amplifier features a 15MHz gain-bandwidth product and 6V/us slew rate which enables high converter bandwidth for fast transient performance. The resulting PWM duty ratio ranges from 0% to 100%. The RC5039 monitors the output voltage with a window comparator that tracks the DAC output and issues a Power Good signal when the output is Within The RC5039 monitors the current by using the RI)S(QN) of the upper MOSFET which eliminates the need for a current sensing resistor. The RC5039 protects against over-current conditions by inhibiting PWM operation. Built-in over-voltage protection triggers an exter-nal SCR to crowbar the input supply.

The features of RC5039 can be summarized as (1)drives N-Channel MOSFET; (2)operates from +5V or +12V VCC bias; (3)operates from +5V power input; (4)simple single-loop control design: voltage-mode PWM control; (5)fast transient response: high-bandwidth error amplifier; full 0% to 100% duty ratio; (6)excellent output voltage regulation: ±15% over line voltage and temperature; (7)4 Bit digital-to-analog output voltage selection: wide range -20VDC to 35VDC; 01V binary steps; (8)power-good output voltage monitor; (9)over-voltage and over-current fault monitors: does not require extra current sensing element, uses MOSFET's RDs(ON); (10)small converter size: constant frequency operation; 200kHz free-running oscillator programmable from 50kHz to 1MHz.

The absolute maximum ratings of RC5039 are (1)power input voltage VIN: 6V; (2)supply voltage, VCC: +135V; (3)boot voltage, VBOOT - VPHASE: +135V; (4)VCC or I/O voltage: GND -03V to VCC + 03V; (5)ESD classification: Class 2.