ACT88326VA datasheet(23/41 Pages) ACTIVE-SEMI

23 / 41 page

ACT88326VA

Rev 1.0, 29-May-2018

Innovative PowerTM

www.active-semi.com

ActiveSwitcherTM is a trademark of Active-Semi.

rises above the Thermal Interrupt Threshold of typically

135 deg C. It reports a fault when the temperature rises

above the Thermal Shutdown Temperature of typically

160 deg C. A temperature fault transitions the IC to the

THERMAL state and shuts down all outputs unless the

fault is masked. Both the fault and the warning can be

masked via I2C. The temperature warning and fault

flags still provide real-time status even if the faults are

masked. Masking just prevents the faults from being re-

ported via the nIRQ pin.

Pin Descriptions

Many of the ACT88326 input and output pins are con-

figurable via CMI configurations. The following descrip-

tions are refer to basic pin functions and capabilities.

Refer to the CMI Options section in the back of the

datasheet for specific pin functionality for each CMI.

VIN_Bx

VIN_Bx pins are the dedicated input power to the buck

converters. Each buck converter must be bypassed di-

rectly to its PGNDx pin on the top PCB layer with a 10uF

capacitor.

AVIN

AVIN is the input power to the LDOs. It also powers the

IC’s analog circuitry. AVIN must be bypassed directly to

AGND on the top PCB layer with a 1uF ceramic capac-

itor.

VIN_IO

This is the bias supply input to the IC’s digital circuitry.

It powers the GPIO pins. VIN_IO is typically connected

to the VIN_Bx pins, but can be powered from a different

voltage rail if desired. VIN_IO should be bypassed to

PGNDx with a 1uF ceramic capacitor.

nPB

nPB is the push button input pin and provides multiple

system level functions based on its impedance to

ground and “press” time. Power On and Power Cycle1

are typically implemented with a single normally open,

momentary pushbutton switch to ground through 50kΩ.

Power Off and Power Cycle2 are typically implemented

with a single normally open, momentary pushbutton

switch or a “pin hole” pushbutton to ground through 1kΩ.

Power On – This sequence starts up the IC and turns

the outputs on. Initiate Power On by momentarily pulling

nPB to ground through a 50kΩ resistor. The IC

automatically starts turning on the outputs after 32ms.

All outputs must be in regulation and the nPB must be

asserted low for longer than the time programmed by

the I2C bit PB WAIT TIME SET. After the programed time,

the IC enters the ACTIVE state and operates normally.

If nPB is deasserted before the required time, the IC

automatically turns all outputs off and goes back to the

POWER OFF state. If a fault is detected before nPB is

released, the IC automatically turns all outputs off and

goes back to the POWER OFF state. Note that nPB can

be asserted indefinitely, but the IC does enter the

ACTIVE state until it is released.

Power Cycle1 – This sequence momentarily turns all

outputs off and automatically restarts them. Initiate

Power Cycle1 by momentarily pulling nPB to ground

through a 50kΩ resistor for >4s. When nPB transitions

back high, the IC transitions from its current operating

state to the POWER OFF state for 0.5s. It then

transitions to the POWER SEQUENCE START state for

0.5s before going to the ACTIVE state. Note that I2C

enable the Power Cycle1 function. If nPB is pulled low

for <4s, no action is taken.

Power Off – This sequence turns all outputs off, and

they stay off until the user actively initiates a Power On

sequence. Initiate Power Off by pulling nPB to ground

through a 50kΩ resistor for >6s. After 6s, the IC

transitions from its current operating state to the

POWER OFF state and turns all outputs off. Once in the

POWER OFF state and nPB is released high, the IC

follows normal programmed functionality to leave

POWER

OFF.

Note

that

I2C

bit

EN_PB_PWROFF must be set to 1 to enable the Power

Off function. If nPB is pulled low for <6s, no action is

taken.

Soft Reset – This sequence pulls nRESET low to reset

the system processor, but all ACT88326 outputs stay

turned on. To initiate Soft Reset, pull nPB to ground

through a 1kΩ resistor for 32ms to 4s. nRESET asserts

low after 32ms. When nPB transitions back high, the IC

deasserts the nRESET pin high. The output voltages do

not power cycle during a Soft Reset.

Power Cycle2 – This sequence momentarily turns all

outputs off and automatically restarts them. Initiate

Power Cycle1 by momentarily pulling nPB to ground

through a 1kΩ resistor for >4s. When nPB transitions

back high, the IC transitions from its current operating

state to the POWER OFF state for 0.5s. It then

transitions to the POWER SEQUENCE START state for

0.5s before going to the ACTIVE state. Unlike Power

Cycle1, the Power Cycle2 sequence does not require

any I2C register settings.

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