ACT4910 datasheet(22/37 Pages) QORVO

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

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ACT4910

Power Loss Protection with 6A eFuse

As with the input capacitor selection, use X5R or X7R

dielectrics and be sure to consider the capacitor’s DC

bias effects.

STORAGE BOOST CONVERTER

General Description

The ACT4910 contains an integrated peak current-

mode, synchronous boost converter. It minimizes

system level costs by using the same components as

the buck converter. The peak current is adjustable

between 250mA and 950mA, allowing for system

optimization. The output voltage is adjustable between

5V and 36V via I2C registers and an external resistor.

The peak current-mode control topology eliminates the

need for compensation. The boost automatically

charges up the storage capacitors from the input

voltage so they are ready to provide backup power in

the event of a system fault.

Startup

The boost converter automatically starts when the IC

exits the SOFTSTART state. Note that the IC exits the

SOFTSTART state 10ms after the output voltage is

within 200mV of the input voltage. Note that the storage

capacitor voltage is initially checked 100ms after the

boost is enabled. If the storage voltage does not reach

its regulation limit by this time, the I2C STR_UV bit is

set. If the storage capacitors are charging too slowly,

use a larger boost current limit value (set by I2C bits

BST_CLIM in register 0x21h) or smaller storage

capacitance.

When the storage voltage reaches regulation, the boost

enters standby mode and monitors the storage voltage.

It automatically turns back on and “tops off” the storage

capacitors when the storage voltage drops below 95%

of the programmed voltage. The boost converter

automatically turns off if it is “topping off” the storage

capacitors when the IC enters supplement mode.

The average input current when the boost charges the

storage capacitors is approximately ½ of the peak

switching current. The peak switch current is programed

by register BST_CLIM[1:0].

Table 4: Boost Peak Current Settings

BST_CLIM[1:0]

(mA)

250

650

950

1500

Operating Mode

The boost converter operates in peak current mode,

non-fixed frequency mode. The power FET stays on

until its current reaches programmed peak current. It

then turns off until the inductor current drops to 0A, at

which time it turns on again.

Storage Capacitor Voltage Setting

The buck converter output voltage is set by either the

I2C register BSTVSET[4:0], or a combination the

to VSS.

When using only the BSTVSET[4:0] leave the BSET

pin floating. Table 5 shows the programmed storage

voltage. The default value is determined by the IC’s

specific CMI option.

Table 5: Storage Capacitor Voltage Settings with

BSET Pin Open

BSTVSET[3:0]

BSTVSET[4]

0000

21V

0001

5.6V

22V

0010

23V

0011

24V

0100

25V

0101

10V

26V

0110

11V

27V

0111

12V

28V

1000

13V

29V

1001

14V

30V

1010

15V

31V

1011

16V

32V

1100

17V

33V

1101

18V

34V

1110

19V

35V

1111

20V

36V

Using both the BSTVSET[4:0] register and an external

resistor provides additional output voltage resolution. In

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