US1528

Preliminary

CMOS IC

UNISONICTECHNOLOGIESCO.,LTD

6 of 8

www.unisonic.com.tw

QW-R502-457.b

APPLICATIONS INFORMATION

Supply Filtering

In order to control supply transients, a bypass capacitor is located nearly between IN to GND. 0.1µF ~ 1µF is

suitable (See Figure 1). Without a bypass capacitor, an output short may cause sufficient ringing on the input (from

supply lead inductance) to damage internal control circuitry.

EN

For a clearly defined input, the EN/EN pin, with 0.2V hysteresis, must be driven logic high or logic low. Floating

Soft Start

The UTC US1528 is high impedance when off and slowly becomes a low impedance as it turns on. This

reduces inrush current and related voltage drop that results from charging a capacitive load, satisfying the USB

voltage drop requirements, for bus-powered applications as shown in Figure 2.