ACT3780 datasheet(12/20 Pages) ACTIVE-SEMI

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ACT3780

Rev 8, 09-Jul-13

Innovative PowerTM

- 12 -

www.active-semi.com

Active-Semi Proprietary―For Authorized Recipients and Customers

ActivePath

TM is a trademark of Active-Semi.

CHG_IN Voltage

nACOK

VUVLO < VCHG_IN < VOVP

Low

VCHG_IN > VOVP

High

VCHG_IN < VUVLO

High

nSTAT3

Low

High

VBAT STATE

nBLV2

nBLV1

VBAT < 2.8V

Low

2.8V ≤ VBAT < 3.6V

Low

High

3.6V ≤ VBAT < 4V

High

Low

4V ≤ VBAT

High

Charging Status Indication

The ACT3780 provides nSTAT1 and nSTAT2

Outputs to indicate the Charging Status of the

charger. These are two open-drain outputs which

sink current went asserted and high-Z otherwise.

These outputs have internal 6mA current limits, and

are capable of directly driving LEDs, without the

need of current-limiting resistors or other external

circuitry, for a visual charge-status indication. To

drive an LED, simply connect the LED between

each pin and an appropriate supply (typically VSYS).

For a logic level indication, simply connect a

resistor from each output to a appropriate voltage

supply. For more details, see table 2 for LED

indication:

Table 2:

Charging Status Indication Table

Battery Voltage Level Indication

When the battery is being charged, the ACT3780

senses VBAT and features nBLV1 and nBLV2 as

two battery voltage level indicator outputs. These

are two open-drain outputs which sink current

whenever asserted. For logic level indication,

simply connect a resistor from each output to an

appropriate voltage supply. See below table 3 for

more information:

Table 3:

Battery Voltage Level Indication Table

nACOK Output

The ACT3780's nACOK output provides a logic-

level indication of the status of the voltage at

CHG_IN. nACOK is an open-drain output which

sinks current when a valid input is applied to

CHG_IN.

Table 4:

nACOK Output Table

Over Voltage Protection (OVP)

The ACT3780 provides over voltage protection

function. When the ACT3780 detects the voltage at

CHG_IN pin is greater than 6.9V, it automatically

turns off the Q1 Power FET and turns on the Q2 to

supply the system load from the battery.

nSTAT3 Output

The ACT3780's nSTAT3 output provide a logic level

indication of OVP. This is an open-drain Output

which sinks current whenever VCHG_IN is greater

than 6.9V.

Enable/Disable Input

The ACT3780's EN is used to enable the IC. Driving

this pin to a logic high enables the ACT3780.

Driving EN pin to a logic low forces the device to

enter suspend mode. In suspend mode, if a valid

input is present at CHG_IN pin, Q1 is turned off.

And the system is powered by the battery via Q2.

This feature is designed to limit the power drawn

from the input supply (such as USB in suspend

mode).

CC/CV Regulation Loop

At the core of the ACT3780's battery charger is a

CC/CV regulation loop, which regulates either

current or voltage as necessary to ensure fast and

safe charging of the battery. In a normal charge

cycle, this loop regulates the current to the value

set by the external resistor at the ISET pin.

Charging continues at this current until the battery

cell voltage reaches the termination voltage (default

is 4.2V or 4.1V). At this point the CV loop takes

over, and charge current is allowed to decrease as

necessary to maintain charging at the termination

voltage.

Enable/Disable Charging

The ACT3780's DCCC pin can be used to disable

charging. By floating the DCCC pin, the charger will

be disabled.

STATE

nSTAT1

nSTAT2

Precondition

Low

Fast Charge

Low

High

Charge Complete

High

Disabled

High

Input Floating

High

Fault

High

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