ACT2801 datasheet(10/25 Pages) ACTIVE-SEMI

10 / 25 page

Rev 9, 14-Mar-17

Innovative PowerTM

- 10 -

www.active-semi.com

ACT2801/ACT2801B/ACT2801C

FUNCTIONAL DESCRIPTION

ACT2801/ACT2801B/ACT2801C is a complete

battery

charging

and

discharging

power

management solution for applications of single-cell

lithium-based backup battery pack or power bank.

There is a power path from input to output with

programmable input current limit. When output is

over loaded, the input switch Q1 starts going into

linear mode and thus output voltage starts to drop.

If output voltage drops below 4.25V, the input

switch Q1 turns off and restart in 2 seconds.

With

the

advanced

ACT2801/ACT2801B/

ACT2801C architecture, a synchronous buck/boost

converter is connected from VOUT to switching

node (SW). With the bidirectional architecture, the

converter could be configured as either buck to

charge battery or boost to discharge battery. With

switching charger and discharger, the higher charge

current and higher conversion

efficiency are

achieved.

Modes of Operation

ACT2801/ACT2801B/ACT2801C has 3 operation

modes: charge mode, boost mode and high-

impedance (HZ) mode. In charge mode, the input

current limit Q1 is enabled and Q2 and Q3 operate

as a buck converter to charge battery. In boost

mode, Q2 and Q3 operate as boost converter to

step battery voltage up to +5V at VOUT, and the

current limit switch Q1 is turned off, and the reverse

current from VOUT to VIN is blocked. In HZ mode,

all the switches are turned off and the drainage

current from battery is very low. ACT2801 system

operation flow chart as shown in Figure 1, and

ACT2801B system operation flow chart as shown in

Figure 2.

Any transitions between boost mode and charge

mode go through HZ mode by turning off all the

switches Q1-Q3 into HZ mode for 2 seconds before

enabling the other mode.

The modes are determined by HZ pin and VIN pin

as shown in the table 1. A valid VIN voltage forces

ACT2801/ACT2801B/ACT2801C into charge mode.

Boost mode is enabled if HZ pin is pulled low and

VIN is invalid or not present. For ACT2801/

ACT2801B, when HZ=0, if PB is pulled low for more

than 30ms, boost converter is enabled. For

ACT2801, during boost on, if PB is pressed more

than 1.5s, boost converter will be off.

Table 1: Mode Selection

Flashlight

ACT2801B has an flashlight function. Once PB is

pressed for 3 seconds, the flashlight is switched on.

The driver will deliver up to 50mA current to the

flashlight. During flashlight on, if PB is pressed for 3

seconds, flashlight will be switched off.

Figure 1:

ACT2801 System Operation Flow Chart

HZ PIN

VIN Valid

Mode

Boost

Charge

Charge Mode

(4.5V<VIN<5.5V)

Boost Mode

(VOUT=5V)

LED Charge Status and

Battery Level Indication

HZ Mode

(Ibat<10µA)

LED Battery Level

Indication Turns on

for 5s

Taking 2s

VIN Invalid and HZ=0

VIN Valid

Taking 2s

HZ: 0—>1 or HZ=0

with: Vbat < 2.9V or PB

is pressed for 1.5s or

Iout < 40mA for 16s

PB is

press

ed fo

r 30m

PB is pre

ssed for

30ms

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