TL497A Datasheet | Texas Instruments

ą TL497A 500Ćm A PEAK STEPĆUP, STEPĆDOWN, INVERTING SWITCHING VOLTAGE REGULATOR SLVS009F - JUNE 1976 - REVISED FEBRUARY 2005 D High Efficiency . . . 60% or Greater D Peak Switch Current . . . 500 m A D Input Current Limit Protection D TTL-patible Inhibit D Adjustable Output Voltage D Input Regulation . . . 0.2% Typ D Output Regulation . . . 0.4% Typ D Soft Start-Up Capability D Can be Used in Buck, Boost, and Inverting Configurations description/ordering information D, N, OR PW PACKAGE (TOP VIEW) P INPUT INHIBIT FREQ CONTROL SUBSTRATE GND CATHODE ANODE 1 2 3 4 5 6 7 14 VCC 13 CUR LIM SENS 12 BASE DRIVE† 11 BASE† 10 COL OUT 9 NC 8 EMIT OUT - No internal connection † BASE (11) and BASE DRIVE (12) are used for device testing only. They normally are not used in circuit applications of the device. The TL497A incorporates all the active functions required in the construction of switching voltage regulators. It also can be used as the control element to drive external ponents for high-power-output applications. The TL497A was designed for ease of use in step-up, step-down, or voltage-inversion applications requiring high efficiency. The TL497A is a fixed-on-time variable-frequency switching-voltage-regulator control circuit. The switch-on time is programmed by a single external capacitor connected between FREQ CONTROL and GND. This capacitor, CT, is charged by an internal constant-current generator to a predetermined threshold. The charging current and the threshold vary proportionally with VCC. Thus, the switch-on time remains constant over the specified range of input voltage (4.5 V to 12 V). Typical on times for various values of CT are as follows: TIMING CAPACITOR, CT (p F) ON TIME (µs) 200 250 350 400 500 750 1000 1500 2000 19 22 26 32 44 56 80 120 180 The output voltage is controlled by an external resistor ladder network (R1 and R2 in Figures 1, 2, and 3) that provides a feedback voltage to the parator input. This feedback voltage is...