ACT88430 datasheet(34/74 Pages) QORVO

34 / 74 page

Data Sheet Rev. G, August 2021 | Subject to change without notice

34 of 74

www.qorvo.com

ACT88430

Advanced PMU for Microcontrollers and Solid State Drive Applications

The ACT88430 buck regulators are highly configurable

and can be quickly and easily reconfigured via I2C.

This allows them to support changes in hardware

requirements without the need for PCB changes.

Examples of I2C functionality are given below:

Real-time power good, OV, and current limit status

Ability to mask individual faults

Dynamically change output voltage

On/Off control

Softstart ramp

Slew rate control

Switching delay and phase control

Low power mode

Overcurrent thresholds

Refer to the Qorvo Application Note describing the Reg-

ister Map for full details on I2C functionality and pro-

gramming ranges.

Operating Mode

The buck converters operate in fixed-frequency PWM

mode at medium to heavy loads. They transition to a

proprietary power-saving low power mode at light loads

to save power. Power-save mode reduces conduction

losses by preventing the inductor current from going

negative.

To further optimize efficiency and reduce power losses

at extremely light loads, an additional lower power mode,

LPM, is available. LPM minimizes quiescent current in

between switching cycles. This reduces input current by

approximately 200µA in LPM mode. Light load output

voltage ripple increases from approximately 5mV to

10mV when in LPM mode. Light load voltage droop

when going from light load to heavier loads is only in-

creased by 2-3mV when in LPM mode. LPM allows the

customer to test the IC in their use case and optimize

the balance between power consumption, voltage ripple,

and transient response in their system. Each buck con-

verter's LPM is enabled when I2C bits DISLPM = 0 and

LP_MODE = 1.

Synchronous Rectification

Buck1/2/3/4

each

feature

integrated

synchronous

rectifiers (or LS FETs) to maximize efficiency and

minimize the total solution size and cost by eliminating

the need for external rectifiers.

Enable / Disable Control

When power is applied to the IC, all converters

automatically turn on according to a pre-programmed

sequence. Once in normal operation (ACTIVE state),

each converter can be independently disabled via I2C.

Each CMI version requires a different set of command

to disable a converter, so contact the factory for specific

instructions if needed. Each converter contains an

optional integrated discharge resistor that actively

discharges the output capacitor when the regulator is

disabled. The discharge function is enabled via the I2C

bit Bx_DisPulldown.

Soft-Start

Each

buck

regulator

contains

softstart

circuit

that limits the rate of change of the output voltage,

minimizing input inrush current and ensuring that the

outputs power up monotonically. This circuitry is

effective any time the regulator is enabled, as well as

after responding to a short circuit or other fault condition.

Buck1/2/3 softstart time is adjustable between 150µs to

485µs via their I2C SS_RAMP registers. Buck4

softstart time is adjustable between 25µs to 204µs via

I2C SS_RAMP register. Table 4 summarizes the

softstart settings.

Table 4: Buck Softstart Time (0.8V Reference)

SS_RAMP

Buck1/2/3

Softstart (µs)

Buck4 Softstart

(µs)

000

150

001

200

010

250

011

300

102

100

350

127

101

395

153

110

440

178

111

485

204

Note that when an output’s reference voltage is

changed to 0.6V, the softstart time changes to 75% of

the time in Table 4.

Output Voltage Setting

Buck1/2/3/4 regulate to the voltage defined by I2C

DVS mode. Buck1/2/3/4 each have two programmable

output

voltage

ranges,

Output-Low

Range

and

Output-High Range. Each buck converter’s output

range can be programmed independently of the others.

Note that the output voltage range can NOT be changed

while

the

output

enabled.

Qorvo

does

not

recommend changing the output voltage range from its

default setting because its internal voltage reference is

only trimmed to its default setting. The following table

shows which I2C bits set the output ranges.

Table 5: Buck Output Voltage Programming Ranges

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