ACT5830 datasheet(39/41 Pages) ACTIVE-SEMI

39 / 41 page

SINGLE-CELL Li+ BATTERY CHARGER (CHGR)

ACT5830

Rev 2, 20-Jan-11

Innovative Power

- 39 -

www.active-semi.com

ActivePMU

TM is a trademark of Active-Semi.

2CTM is a trademark of NXP.

TIMOSET

[1:0 ]

PRECONDITION

TIMEOUT

TOTAL CHARGING

TIMEOUT

1 hour

3 hours

1.43 hours

4.3 hours

2 hours

6 hours

INFINITE

FUNCTIONAL DESCRIPTIONS CONT’D

Charge Safety Timer

While monitoring the charge cycle, the ACT5830

utilizes a charge safety timer to help identify

damaged cells and to ensure that the cell is

charged safely. Three timeout options of 1 hour,

1.43 hours, and 2 hours are available, as

programmed by the CHGR/TIMOSET register, and

a timer-disable option is also available for systems

that do not require the ACT5830 to control charge

timeouts.

The bit assignments for each timeout period are set

as follows:

Table 12:

TIMOSET[ ] Timeout Period Options

CHGR State-Machine

PRECONDITION State

new

charging

cycle

begins

with

the

PRECONDITION state. In this state, the cell is

charged at a reduced current of 10% of ISET, the

programmed fast charge current. During a normal

charge cycle, charging continues at this rate until

VBAT reaches the Precondition Threshold Voltage of

2.9V (typ), at which point the charging state

machine jumps to its FAST-CHARGE state. If VBAT

does not reach the Precondition Threshold Voltage

before the Precondition timeout period expires, then

a damaged cell is detected and the state machine

jumps to the TIMEOUT-FAULT State.

FAST-CHARGE State

In FAST-CHARGE mode, the charger operates in

constant-current (CC) mode and charges the cell at

the current programmed by CHGR/ISET. During a

normal charge cycle fast-charge continues until

VBAT reaches the termination voltage programmed

by VSET, at which point the state machine jumps to

the TOPOFF state. If VBAT does not reach VSET

before the total time out period expires then the

state-machine will jump to the “SLEEP” state.

TOP-OFF State

In the TOP-OFF state, the cell is charged in

constant-voltage (CV) mode. With the charge

current limited by the internal chemistry of the cell,

decreases as charging continues. During a normal

charging cycle charging proceeds until the charge

current decreases beyond the End-Of-Charge

(EOC) threshold, defined as 10% of ISET. When

this happens, the state machine terminates the

charge cycle and jumps to the SLEEP state.

SLEEP State

In SLEEP mode the ACT5830 presents a high-

impedance to the battery, allowing the cell to “relax”

and minimizing battery leakage current. The

ACT5830 continues to monitor the cell voltage,

however, so that it can re-initiate charging cycles as

necessary to ensure that the cell remains fully

charged. Under normal operation, the state

machine initiates a new charging cycle by jumping

to the FAST-CHARGE state when VBAT drops below

the Charge Termination Threshold (programmed by

VSET) by more than the Charge Restart Threshold

of 200mV (typ).

SUSPEND State

The ACT5830 features a user-selectable suspend-

charge mode (SUSCHG), which disables the

charger but keeps other circuitry functional.

Charging continues in the SUSPEND state until

CHGR/SUSPEND is cleared, at which point the

charge timer is reset and the state machine jumps

to the PRECHARGE state.

Suspend charge by setting CHGR/SUSCHG = [1].

Permit charging by clearing CHGR/SUSCHG to [0].

TIMEOUT-FAULT State

In order to prevent continued operation with a

damaged cell, there is no direct path to resume

charging once a Timeout Fault occurs. In order to

resume charging, the state machine must jump to

the SUSPEND state as a result of any of the

following events:

1) Microprocessor Sets CHGR/SUSCHG to [1],

2) Microprocessor Pulls nENCHG high,

The input supply is removed or the input supply

voltage drops below the UVLO threshold (4V), or

the battery is removed. Once any of these events

occur, the state machine jumps to the SUSPEND

ACT5830 Datasheet(PDF) 39 Page - Active-Semi, Inc

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