AP1212

Dual USB High-Side Power Switch

Anachip Corp.

www.anachip.com.tw

Rev.1.0 Sep.23, 2004

9/11

Function Description

Error Flag

An open-drained output of N-channel MOSFET, the

FLG output is pulled low to signal the following fault

conditions: input undervoltage, output current limit,

and thermal shutdown.

Current Limit

The current limit threshold is preset internally. It

protects the output MOSFET switches from

damage due to undesirable short circuit conditions

or excess inrush current often encountered during

hot plug-in. The low limit of the current limit

threshold of the AP1212 allows a minimum current

of 0.5A through the MOSFET switches. A current

limit condition will signal the error flag.

Thermal Shutdown

When the chip temperature exceeds 140ºC for any

reason other than overcurrent fault of either one of

the two MOSFET switches, the thermal shutdown

function turns off both MOSFET switches and

signal the error flag. A hysteresis of 10ºC prevents

the MOSFETs from turning back on until the chip

temperature drops to below 130ºC.

Supply Filtering

A 0.1µF to 1µF bypass capacitor from IN to GND,

located near the device, is strongly recommended

to control supply transients. Without a bypass

capacitor, an output short may cause sufficient

ringing on the input (from supply lead inductance)

to damage internal control circuitry.

Transient Droop Requirements

USB support dynamic attachment (hot plug-in) of

peripherals. A current surge is caused by the input

capacitance of downstream device. Ferrite beads

are recommended in series with all power and

ground connector pins. Ferrite beads reduce EMI

and limit the inrush current during hot-attachment

by filtering high-frequency signals.

Short Circuit Transient

Bulk capacitance provides the short-term transient

current needed during a hot-attachment event. With

a 33µF, 16V tantalum or 100µF, 10V electrolytic

capacitor mounted close to downstream connector

per port should provide transient drop protection.

Printed Circuit Layout

The power circuitry of USB printed circuit boards

requires a customized layout to maximize thermal

dissipation and to minimize voltage drop and EMI.

Marking Information

Part Number

1

4

PDIP/SOP

Logo

Enable Type

H: Active High

L: Active Low

ID code: internal

Year: "01" =2001

"02" =2002

Xth week: 01~52

8

5

AP1212 X

YY WW X X

(Top View)

Blank: normal

L: Lead Free Package