ACT81460 datasheet(39/67 Pages) QORVO

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ACT81460

Low Power PMIC With Integrated Linear Charger

Data Sheet Rev. C, January 2022 | Subject to change without notice

39 of 67

www.qorvo.com

BUCK-BOOST REGULATOR

General Description

ACT81460 contains a fully integrated, four-switch,

buck-boost regulator. It operates from an input voltage

range of 2.7V to 5.5V and provides an output range

between 3.2V and 5.0V.

The four integrated MOSFETS minimize the cost and

size of the solution with minimal external components

needed for the buck-boost function. The buck-boost can

be configured to operate in the following modes:

•

Buck-boost Only mode

•

Buck Only mode

•

Boost Only mode

•

Auto Buck / Buck-Boost / Boost mode

•

Auto Buck-Boost / Boost mode

The operating mode cannot be changed during opera-

tion. Refer to the CMI Options section for each CMI’s

specific setting. Contact Qorvo if a different operating

configuration is needed.

CCM

mode,

there

are

four

user-selectable

frequencies

between

1.5MHz

and

3.3MHz.

The

buck-boost is available with a variety of standard and

custom output voltages and may be software-controlled

via the I2C interface for systems that require advanced

power management functions.

Operating Mode

The buck-boost regulator emulates operation of a fixed-

frequency regulator at medium to heavy loads. It

transitions to a proprietary power-saving mode at light

loads to save power and improve efficiency. The

buck-boost is optimized to reduce its input current dur-

ing off/shutdown and standby modes when there is no

load current and the regulator is left on with the output

regulating. The output voltage can be configured via I2C.

Synchronous Rectification

The buck-boost features an integrated full H-bridge with

two high side (HS) and two low side (LS) power

MOSFETs. The LS MOSFETS are used in a fully

synchronous mode to maximize efficiency and minimize

the total solution size and cost by eliminating the need

for external rectifiers.

Note that an additional Schottky diode is required when

the output voltage is greater than 4.7V. Connect the

anode to SWBB2 and the cathode to VBBST. The diode

should be placed on the top layer with direct

connections to these two pins. Refer to the EVK for

layout details.

Soft-Start

The buck-boost regulator includes an internal 800µs

soft-start ramp which limits the rate of change of the

output voltage, minimizing input inrush current and

ensuring that the output powers up in a monotonic

manner that is independent of loading on the outputs.

This circuitry is effective any time the regulator is

enabled, as well as after responding to a short-circuit or

other fault condition and during retry after a fault.

Output Voltage Setting

Output voltage for the buck-boost regulator can be

programmed in 50mV steps from 3.20V to 5.0V. The

buck-boost regulates to the voltage defined by I2C

and 5.0V in 50mV steps. The following equation

calculates the output voltage based on the VSET0

Vbuck-boost = 3.2V + VSET0 * 0.05V

Where VSET0 is the decimal equivalent of the value in

the I2C VSET0 register. The VSET0 register contains an

unsigned 6-bit binary value. As an example, if the

VSET0 register contains 100100b (36decimal), the

output voltage is 5.0V.

Changes to the output voltage are intended to be

performed with CMI settings. The output voltage should

not be changed in final production. For development

and experimentation, the output voltage may be

changed by +-20% from the default setting. Voltage

changes larger than +/- 20% require different factory

trim settings (new CMI). Programming the output

voltage farther than 20% from the default setting may

damage the IC.

Table 6 shows the output voltage as a function of the

VSET0 register setting. Do not program the VSET0

registers to a value greater than 100100b. Programming

higher than this may damage the IC.

Buck-Boost Output Voltage (V)

VSET0 [5:3]

000

001

010

011

100

101

110

111

000

3.20

3.60

4.00

4.40

4.80

N/A

001

3.25

3.65

4.05

4.45

4.85

N/A

010

3.30

3.70

4.10

4.50

4.90

N/A

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