ACT8740 datasheet(13/40 Pages) ACTIVE-SEMI

13 / 40 page

SYSTEM MANAGEMENT

ACT8740

Rev PrB, 25-Feb-08

Innovative Products. Active Solutions.

- 13 -

www.active-semi.com

ActivePMU

TM is a trademark of Active-Semi.

2CTM is a trademark of Philips Electronics.

nMSTR Enable Input

In most applications, connect nMSTR to an active

low, momentary push-button switch to utilize the

ACT8740’s closed-loop enable/disable functionality.

If a momentary-on switch is not used, drive nMSTR

to GA or to a logic low to initiate a startup se-

quence.

nIRQ Output

The ACT8740 provides an active-low, open-drain

push-button status output that sinks current when

nMSTR is driven to a logic-low. Connect a pull-up

resistor from nIRQ to an appropriate voltage supply.

nIRQ is typically used to drive the interrupt input of

the system processor, and is useful in a variety of

software-controlled enable/disable control routines.

Thermal Shutdown

The ACT8740 integrates thermal shutdown protec-

tion circuitry to prevent damage resulting from ex-

cessive thermal stress, as may be encountered un-

der fault conditions. This circuitry disables all regu-

lators if the ACT8740 die temperature exceeds

160°C, and prevents the regulators from being en-

abled until the IC temperature drops by 20°C (typ).

ACT8740 数据表(PDF) 13 Page - Active-Semi, Inc