ACT88430 datasheet(37/74 Pages) QORVO

37 / 74 page

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

37 of 74

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ACT88430

Advanced PMU for Microcontrollers and Solid State Drive Applications

require a 22uF output capacitor each. In order to ensure

stability, the actual Buck1 capacitance should be

greater than 33uF while Buck2, Buck3, and Buck4

should be greater than 15uF. The output capacitance

can be increased to reduce output voltage ripple and

improve load transients if needed. Design for an output

ripple voltage less than 1% of the output voltage. The

following equation calculates the output voltage ripple

as a function of output capacitance.

VRIPPLE

= ∆��

8∗��∗��

Where ΔIL is the inductor ripple current, FSW is the

switching frequency, and COUT is the output capacitance

after taking DC bias into account.

Be sure to consider the capacitor’s DC bias effects and

maximum ripple current rating when using capacitors

smaller than 0805.

A capacitor’s actual capacitance is strongly affected

by its DC bias characteristics. The output capacitor is

typically an X5R, X7R, or similar dielectric. Use of Y5U,

Z5U, or similar dielectrics are not recommended due to

their wide variation in capacitance over temperature and

voltage ranges.

LDO CONVERTERS

General Description

The ACT88430 contains three fully integrated low

dropout linear regulators (LDO). LDO1 is an 800mA

output, while LDO2 and LDO3 are 200mA outputs. The

LDOs are require only two small external components

(Cin, Cout) for operation. They ship with default output

voltages that can be modified via the I2C interface

for systems that require advanced power management

functions.

LDO1 has a dedicated input pin. LDO2 and LDO3 share

an input pin. The LDOs can operate from different input

voltages than the buck converters. LDO1 and LDO2/3

can operate from different input voltage from each other.

LDO1 has the option to be operated as a standard LDO

or as a load switch.

Enable / Disable Control

When power is applied to the IC, all LDOs 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. Each LDO’s discharge function is enabled via

its I2C bit DIS_PULLDOWN.

Soft-Start

Each LDO contains a softstart circuit that limits the rate

of change of the output voltage, minimizing input inrush

current and ensuring that the outputs power up in a

monotonically. This circuitry is effective any time the

LDO is enabled, as well as after responding to a short

circuit or other fault condition. Each LDO’s softstart time

is adjustable via its I2C bits SS_RAMP.

LDO1 is adjustable between 226µs and 570µs,

depending on output voltage.

LDO2 is adjustable between 130µs and 220µs,

depending on output voltage

LDO3

adjustable

between

65µs

and

130µs,

depending on output voltage

Table 6 summarizes the LDO softstart programming

ranges.

Table 6: LDO Softstart Ranges

LDOx

Softstart

Set-

ting

LDO1

softstart

(us)

LDO2

softstart

(us)

LDO3

softstart

(us)

LDOx_SS

226

130

323

133

440

170

570

220

126

Output Voltage Setting

LDO1/2/3 regulate to the voltage defined by I2C

registers LDO

VSET registers. Unlike the

buck

converters, the LDOs only have one VSET register.

LDO2/3 each have two programmable output voltage

ranges, Output-Low Range and Output-High Range.

Each

LDO’s

output

range

can

programmed

independently of the others. Note that the output voltage

range can NOT be changed while the output is enabled.

Qorvo does not recommend changing the output volt-

age 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 7: LDO Output Voltage Programming Ranges

Bit

Setting

Range

LDO1

n/a

Output-

High

LDO2

0x81h

RANGE_LDO2

Output-

Low

Output-

High

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