ACT5880 datasheet(78/87 Pages) ACTIVE-SEMI

78 / 87 page

ACT5880

Rev 2, 03-Sep-13

- 78 -

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I2CTM is a trademark of NXP.

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The charger circuit in the ACT5880 deploys the

constant current and constant voltage scheme for

charging,

with

pre-condition

charging

and

suspending. Most parameters for CC/CV control is

programmable, together with the battery installed

detection, the adaptor charging detection, the

battery thermal condition, the die temperature

regulation, the charging time-out counters and the

LDO mode operation, it composes an autonomic-

able, flexible yet powerful battery management sub

system, which satisfies most applications.

Program and Manipulate

Most of the charging profile control parameters are

programmed by writing respective registers though

the I2C interface. The charge states, the logic inputs

are read and the charge behavior is manipulated

through the same interface by reading or writing

respective bits.

Most programming and manipulation are done with

one time access to respective register. For

changing the battery regulation voltage and the fast

charger current, which are safe related, an enable

bit, the ENVISET[ ] register has to be set firstly, to

avoid the accidental change. Refer to the

section for

more details.

Power Path Management

The ACT5880 has simple power path management.

Refer to Figure 15, the charger only has one

controlled path for pre-condition charging, fast

charging and providing power to the load. By any

time, the regulated voltage and regulated current

apply to the load and the battery simultaneously.

The load directly pours current from the battery or

from the charge path, provides the most efficient

way of using the energy stored in the battery.

This is the most common path management in

cellular phone and smart phone designs. Few

issues need to be carefully designed for the

optimizing use of this path management:

1.Start from a weak/dead battery;

2.Charging termination.

The ACT5880 provides rich of programmability and

effective solutions for dealing with these issues

against system designer's trade-off. The ACT5880

has a pre-condition timer and a total charge timer

for safe charging of a weak/dead battery, and it

does not start the system until the battery voltage is

charged to high enough voltage. The ACT5880

itself is designed to start at as low voltage as the

precondition finishes, which reduces the time to

wait before start. Additionally, the ACT5880

provides a LDO mode for starting system without

battery.

Figure 15:

The Power Path of the Charger in the ACT5880.

The ACT5880 provides rich of programmability and

effective solutions for dealing with these issues

against system designer's trade-off. The ACT5880

has a pre-condition timer and a total charge timer for

safe charging of a weak/dead battery, and it does not

start the system until the battery voltage is charged

to high enough voltage. The ACT5880 itself is

designed to start at as low voltage as the pre-

condition finishes, which reduces the time to wait

before start. Additionally, the ACT5880 provides a

LDO mode for starting system without battery.

When the current goes into load is bigger than the

current threshold for end of charge detection, the

charging termination may never happen. The

system operates in this situation, is known as long

cord powered time operation. In this situation the

system could program the charger to output at a

slightly lower voltage for safe floating.

Adaptor Input Detection

The ACIN is the detection of adaptor charging input,

which is a logic input with precise logic thresholds.

A resistor divider can be used for sensing the

voltage applies at the adaptor input receptacle for

simple detection. Ref to the "USB Charging" and

"Dual Input and USB-OTG Paths" for detection of

USB adaptor.

Battery Installed Detection

A grounded resistor in battery assembly is desired

together with the BATID of the ACT5880 for the

battery installed detection. The BATID is a logic

input with higher voltage precise logic thresholds ,

please refer to the SINGEL-CELL LI+ CHARGER

ELECTRICAL CHARACTERISTICS

table for more

details.

SINGLE-CELL LI+ BATTERY CHARGER

Charger

Control

System

Load

Joint-node

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