ACT5101 datasheet(22/59 Pages) QORVO

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Data Sheet Rev. E, November 2019 | Subject to change without notice

22 of 59

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ACT510x

23V Buck-Boost Converter with Integrated MOSFETs

Output Voltage Setting

The output voltage is programmable between 2.96V

and 23.42V in 20mV steps via by I2C bits VOUT[9:0] in

registers 0x13h and 0x14h.

= 2.96 + 20 ∗

[9:0]

Where VOUT[9:0] is the decimal equivalent of the value

this

For

example,

VOUT[9:0]

0111000100b (452 decimal), the output voltage = 2.96V

+ 0.02V * 452 = 12.00V.

When changing from one output voltage to another, the

slew rate is programmable between 1V/ms and 0.1V/ms

by I2C bits OUTPUT_SLEW[1:0] in register 0x10h. This

allows the output to conform to QC2.0/QC3.0/USB PD/

USB PD + PPS functions for higher output voltages.

The input voltage must always stay above the minimum

allowable input voltage. This voltage is defined by reg-

isters VIN_UV_OFFSET in register 0x1Ah and VIN_UV

in register 0x0Fh. The minimum allowable input voltage

is the VIN_UV_OFFSET voltage minus the VIN_UV

voltage. If the input voltage drops below this value, the

IC turns off the output and goes to the RST state.

Active Discharge

When changing the output voltage to a higher level, the

switcher ramps the output voltage by the programmed

slew rate. When the output voltage is programmed from

a higher to a lower voltage, the voltage drops at a rate

determined by the output capacitance and the load

current. To minimize the fall time in no-load conditions,

the ACT510x can provide a 70mA sink when the output

is transitioning to a lower output voltage. Enable this

feature by writing 1 into I2C bit PULLDOWN_RAMP.

The 70mA load turns on until the output voltage goes

into regulation.

Enable Delay

Once the IC has the valid conditions for startup, the

Enable Delay timer is enabled. The timer options allow

a 0ms to 1s delay. The startup delay is controlled by the

I2C bits EN_DLY[1:0]

Soft Start

After the Enable Delay has completed, the IC starts the

output using a soft start function programmable by the

I2C bits SOFT_START in register 0x0Eh. The softstart

time is independent of the output voltage setting.

Setting Maximum Output Current

The maximum output current, IOUT_MAX, is set by a

combination of a current sense resistor, an OLIM

resistor, and a scaling factor defined by I2C bits CC[6:0]

in register 0x17h. The maximum allowable output

current is 5A. Figure 9 shows the hardware circuitry that

sets IOLIM. IOLIM is the maximum output current set by

hardware. The actual output current limit, IOUT, can be

scaled from 1% to 100% of IOLIM in 1% steps. The

following equation defines the final maximum output

current.

I _ = I

∗ CC[6:0]

Where IOLIM is the hardware programmed output current

limit and CC[6:0] is the scaling factor. CC[6:0] is the

decimal equivalent value in this register. For example,

if IOLIM, is programmed to 4A and CC[6:0] = 1001011b

(75% decimal), the final maximum output current = 4A *

0.75 = 3A.

Note that CC[6:0] is a 7 bit register and can be

programmed between 0x00h and 0x7Fh (0% and

127%). If a value of 0x00h is written to the register, the

output current to 1%. If a value above 0x64h (100%) is

written to the register, the IC retains the written value,

but sets the maximum output current to 100%.

To Output

RCS_OUT

ROLIM

ROSRN

ROSRP

COSR

OSRN

OSRP

VOUT

OLIM

RCS_COMP

CCS_COMP

Figure 9: Output Current Limit Circuitry

The current sense resistor and OLIM resistor set the

IOLIM current.

!"#

= 1000

' !"# ∗ '()_

Where ROLIM is the resistor from the OLIM pin to AGND

in ohms and RCS_OUT is the current sense resistor value

in ohms. The term 1000V^2/A is a constant with the

units volts^2/Ampere.

The current sense resistor, RCS_OUT, value should be

chosen to give a maximum current sense voltage

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