HA17524FP Datasheet | Hitachi Semiconductor

Features - - - - - - - Pulse width modulation (PWM) Wide oscillation frequency range: 450 k Hz(typ) Low quiescent current: 5 m A typ Good line regulation (0.2% typ) and load regulation (0.4% typ) Independent output stages for 2 channels Wide external circuit applications including single-end and push-pull method Reference power source output stage and switching output stage include current limiting protection circuit. Ordering Information Type No. HA17524P HA17524FP Package 16 pin dual in line plastic(DP-16) 16 pin flat plastic (FP-16DA) Pin Arrangement INV. Input NON-INV. Input OSC Out CL(+) CL(- ) RT CT GND 1 2 3 4 5 6 7 8 16 15 14 13 12 11 10 9 (Top View) V REF VCC E2 C2 C1 E1 SHUT DOWN P HA17524P/FP Functional Description Principals of HA17524 Operation The HA17524 switching regulator circuit, using pulse width modulation (PWM), is constructed as shown in figure 1. Timing resistances RT and timing capacitance C T control the oscillation frequency. CT is charged by a constant current generated by RT . Ramp signals (saw-tooth waves) at the CT terminal generated by this oscillator is available for reference input signal to parator which control the pulse width. VREF VCC 15 Ref. Volt. +5 V RT 6 CT 7 (Ramp) Osc. 16 +5 V to internal circuitry +5V OSC Out Q 3 Flip Flop Q +5V - 12 C1 NOR Q1 11 E 1 13 C2 NOR Q2 14 E 2 4 CL(+) 5 CL(- ) parator INV. Input 1 NON-INV. Input 2 GND 8 +5V - Error Amp. + + +5V + C.L. - 10 SHUT DOWN 1kΩ 10kΩ 9 P Current Limiter Figure 1 HA17524 Block Diagram The reference voltage connects to the non-inverted or inverted input terminal of the error amplifier via resistance divider (figure 2). The output voltage from the error amplifier is pared with the ramp signal capacitance CT (figure 1). The parator can provide a signal with modulated pulse width. This signal, then, controls output transistors Q1 and Q 2, making an open loop to stabilize output voltage. Outputs form the error amplifier the current limiter, and the shut-down circuit...