ACT88326VA datasheet(20/41 Pages) ACTIVE-SEMI

20 / 41 page

ACT88326VA

Rev 1.0, 29-May-2018

Innovative PowerTM

www.active-semi.com

ActiveSwitcherTM is a trademark of Active-Semi.

the ACTIVE state, the IC can stay in that state or auto-

matically transition to either the SLEEP or DPSLP state

depending on the status of the inputs in Tables 1 and 2.

Shutdown is typically accomplished by forcing the sys-

tem to transition to the DPSLP state. Shutdown can also

be accomplished with the nPB pin or by setting the I2C

POWER OFF bit to a 1.

Sequencing

The ACT88326 provides the end user with extremely

versatile sequencing capability that can be optimized for

many different applications. Each of the five outputs has

four basic sequencing parameters: input trigger, turn-on

delay, turn-off delay, and output voltage. The buck

converters also have softstart time control. Each of

these parameters is controlled via the ICs internal

registers. The specifics for this IC as well as others are

detailed at the end of the datasheet. Contact

sales@active-semi.com

for

custom

sequencing

configurations. Refer to the Active-Semi Application

Note AN111, ACT88326VA102 Register Definitions, for

full details on the I2C register map functionality and

programming ranges.

Input trigger. The input trigger for a regulator is the

event that turns that regulator on. Each output can have

a separate input trigger. The input trigger can be the

internal power ok (POK) signal from one of the other

regulators, the internal VIN POK signal, or an external

signal applied to an input pin such as EXT_PG or GPIO.

This flexibility allows a wide range of sequencing

possibilities, including having some of the outputs be

sequenced with an external power supply or a control

signal from the host. As an example, if the LDO1 input

trigger is Buck1, LDO1 will not turn on until Buck1 is in

regulation. Input triggers are defined at the factory and

can only be changed with a custom CMI configuration.

The GPIOx outputs can be connected to an internal

power supply’s POK signal and used to trigger external

supplies in the overall sequencing scheme. The GPIOx

inputs can also be connected to an external power

supply’s power good output and used as an input trigger

for an ACT88326 supply.

Turn-on Delay. The turn-on delay is the time between

an input trigger going active and the output starting to

turn on. Each output’s turn-on delay is configured via its

I2C bit ON DELAY. Turn-on delays can be changed after

the IC is powered on, but they are volatile and reset to

the factory defaults when power is recycled.

Turn-off Delay. The turn-off delay is the time between

an input trigger going inactive and the output starting to

turn off. Each output’s turn-off delay is configured via its

I2C bit OFF DELAY. Turn-off delays can be changed

after the IC is powered on, but they are volatile and reset

to the factory defaults when power is recycled.

Softstart Time. The softstart time is the time it takes an

output to ramp from 10% to 90% of its programmed

voltage. All buck converter softstart times are controlled

by a single I2C bit ALL_BUCKS_FASTER_SS. When

set to 0, the softstart times are 600µs. When set to 1,

the softstart times are 250µs. The default softstart time

can be changed after the IC is powered on, but it is

volatile and resets to the factory defaults when power is

recycled.

Output Voltage. The output voltage is each regulator’s

desired voltage. Each buck’s output voltage is

programmed via its I2C bits VSET0 and VSET1. The

output regulates to VSET0 in ACTIVE mode. They can

be programmed to regulate to VSET1 in DVS, SLEEP,

and DSPSLP modes. Each LDO has a single register,

VSET, to set its output voltage. Each output’s voltage

can be changed after the IC is powered on, but the new

setting is volatile and is reset to the factory defaults

when power is recycled. Output voltages can be

changed on the fly. If a large output voltage change is

required, it is best to make multiple smaller changes.

This prevents the IC from detecting an instantaneous

over or under voltage condition because the fault

thresholds are immediately changed, but the output

takes time to respond.

Dynamic Voltage Scaling

On-the-fly dynamic voltage scaling (DVS) for the three

buck converters is available via either the I2C interface

or a GPIO. DVS allows systems to save power by

quickly adjusting the microprocessor performance level

when the workload changes. Note that DVS is not a

different operating state. The IC operates in the ACTIVE

state, but just regulates the outputs to a different voltage.

Each buck converter operates at its VOUT0 voltage in

normal operation and operates at its VOUT1 voltage

when the DVS input trigger is active. DVS can be

implemented three ways.

The first method is to individually put each buck

converter in DVS by manually writing a new voltage

regulation setpoint into its VOUT0 register.

DVS can also be implemented for all buck converters at

one time via a single GPIO input. The IC’s specific CMI

determines the specific GPIO used for DVS. This setting

can be modified with a custom CMI.

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