ACT8847 datasheet(29/42 Pages) ACTIVE-SEMI

29 / 42 page

ACT8847

Rev 9, 27-June-17

Innovative PowerTM

- 29 -

www.active-semi.com

ActivePMUTM is a trademark of Active-Semi.

I2CTM is a trademark of NXP.

nRSTO Output

nRSTO is an open-drain output which asserts low

upon startup or when manual reset is asserted via

the nPBIN input. When asserted on startup, nRSTO

remains low until reset time-out period expires.

When asserted due to manual-reset, nRSTO

immediately asserts low, then remains asserted low

until the nPBIN input is de-asserted and the reset

time-out period expires.

Connect a 10kΩ or greater pull-up resistor from

nRSTO to an appropriate voltage supply.

nIRQ Output

nIRQ is an open-drain output that asserts low any

time an interrupt is generated. Connect a 10kΩ or

greater pull-up resistor from nIRQ to an appropriate

voltage supply. nIRQ is typically used to drive the

interrupt input of the system processor.

Many of the ACT8847's functions support interrupt-

generation as a result of various conditions. These

are typically masked by default, but may be

unmasked via the I2C interface. For more

information about the available fault conditions,

refer to the appropriate sections of this datasheet.

Push-Button Control

The ACT8847 is designed to initiate a system

enable sequence when the nPBIN multi-function

input is asserted. Once this occurs, a power-on

sequence commences, as described below. The

power-on sequence must complete and the

microprocessor must take control (by asserting

PWRHLD) before nPBIN is de-asserted. If the

microprocessor is unable to complete its power-up

routine successfully before the user releases the

push-button, the ACT8847 automatically shuts the

system down. This provides protection against

accidental or momentary assertions of the push-

button. If desired, longer “push-and-hold” times can

be implemented by simply adding an additional time

delay before asserting PWREN or PWRHLD.

Control Sequences

The ACT8847 features a variety of control

sequences that are optimized for supporting system

enable and disable, as well as SLEEP mode of the

Samsung S5PC210 / S5PV310 processors.

Enabling/Disabling Sequence

A typical enable sequence is initiated whenever the

nPBIN is asserted low via 50KΩ resistance. The

power control diagram is shown in Figure 3. During

the boot sequence, the microprocessor must assert

PWRHLD

(XPSHOLD),

and

PWREN

(XPWRRGTON), to ensure that the system remains

powered after nPBIN is released. Once the power-

up routine is completed, the system remains

enabled after the push-button is released as long as

PWRHLD is asserted high. If the processor does

not assert PWRHLD before the user releases the

push-button, the boot-up sequence is terminated

and all regulators are disabled. This provides

protection against "false-enable", when the push-

button is accidentally depressed, and also ensures

that the system remains enabled only if the

processor successfully completes the boot-up

sequence.

As with the enable sequence, a typical disable

sequence is initiated when the user presses the

push-button, which interrupts the processor via the

nPBSTAT output. The actual disable sequence is

completely

software-controlled,

but

typically

involved initiating various “clean-up” processes

before the processor finally de-asserts PWRHLD.

SLEEP Mode Sequence

The ACT8847 supports S5PC210 / S5PV310

processors’ SLEEP mode operation. Once a

successful power-up routine has been completed,

SLEEP mode may be initiated through a variety of

software-controlled mechanisms.

SLEEP mode is typically initiated when the user

presses the push-button during normal operation.

Pressing the push-button asserts the nPBIN input,

which

asserts

the

nPBSTAT

output,

which

interrupts the processor. In response to this

interrupt

the

processor

should

de-assert

PWREN(XPWRRGTON),

disabling

REG2/3/4/5/8/9/10/11. PWRHLD should remain

asserted during SLEEP mode so that REG1/6/7/12

remain enabled.

The ACT8847 wakes up from SLEEP mode when

either

the

push-button

and/or

PWREN

(XPWRRGTON)

is asserted. In either case,

REG2/3/4/5/8/9/10/11 are enable which allow the

system to resume normal operation.

ACT8847 Datasheet(PDF) 29 Page - Active-Semi, Inc

ACT8847 Datasheet(HTML) 29 Page - Active-Semi, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Datasheet Download

Link URL