ACT8934A datasheet(39/45 Pages) ACTIVE-SEMI

39 / 45 page

ACT8934A

Rev 1, 22-Oct-12

Innovative Power

ActivePMU

TM and ActivePathTM are trademarks of Active-Semi.

2CTM is a trademark of NXP.

- 39 -

www.active-semi.com

include pin-programmable fast-charge current and

one current-limited nSTAT output that can directly

drive LED indicator or provide a logic-level status

signal to the host microprocessor

Dynamic Charge Current Control (DCCC)

The ACT8934A's ActivePath charger features

dynamic charge current control (DCCC) circuitry,

which acts to ensure that the system remains

powered while operating within the maximum output

capability of the power adapter. The DCCC circuitry

continuously monitors VVSYS, and if the voltage at

VSYS drops by more than 200mV, the DCCC

circuitry automatically reduces charge current in

order to prevent VVSYS from continuing to drop.

Charge Current Programming

The ACT8934A's ActivePath charger features a

flexible charge current-programming scheme that

combines the convenience of internal charge

current programming with the flexibility of resistor

based charge current programming. Current limits

and charge current programming are managed as a

function of the ACIN and CHGLEV pins, in

combination with RISET, the resistance connected to

the ISET pin.

ACIN is a logic input that configures the current-limit

of ActivePath's linear regulator as well as that of the

battery charger. ACIN features a precise 1.2V logic

threshold, so that the input voltage detection

threshold may be adjusted with a simple resistive

voltage divider. This input also allows a simple, low-

cost dual-input charger switch to be implemented

with just a few, low-cost components.

When the voltage at ACIN is above the 1.2V

threshold, the charger operates in “AC-Mode” with a

charge current programmed by RISET, and the RISET

is given by:

RISET (kΩ) = 2336 × (1V/ICHG (mA)) - 0.205

With a given RISET then charge current will reduce 5

times when CHGLEV is driven low.

When ACIN is below the 1.2V threshold, the

charger operates in “USB-Mode”, with a maximum

CHGIN input current and charge current defined by

the CHGLEV input; 450mA, if CHGLEV is driven to

a logic-high, or 100mA, if CHGLEV is driven to a

logic-low.

The ACT8934A's charge current settings are

summarized in Table 10.

Note that the actual charge current may be limited

to a current lower than the programmed fast charge

current due to the ACT8934A’s internal thermal

regulation loop. See the Thermal Regulation section

for more information.

Charger Input Interrupts

In order to ease input supply detection and

eliminate the size and cost of external detection

circuitry, the charger has the ability to generate

interrupts based upon the status of the input supply.

This function is capable of generating an interrupt

when the input is connected, disconnected, or both.

An interrupt is generated any time the input supply

is connected when INSTAT[ ] bit is set to 1 and the

INCON[-] bit is set to 1, and an interrupt is

generated any time the input supply is disconnected

when INSTAT[ ] bit is set to 1 and the INDIS[ ] bit is

set to 1.

INDAT[-] indicates the status of the CHGIN input

supply. A value of 1 indicates that a valid CHGIN

input (CHGIN UVLO Threshold<VCHGIN<CHGIN

OVP Threshold) is present, a value of 0 indicates a

valid input is not present.

When an interrupt is generated by the input supply,

reading the INSTAT[ ] returns a value of 1.

INSTAT [ ] is automatically cleared to 0 upon

reading. When no interrupt is generated by the

input supply, reading the INSTAT[ ] returns a value

of 0.

When responding to an Input Status Interrupt, it is

often useful to know the state of the ACIN input. For

example, in a dual-input charger application

knowing the state of the ACIN input can identify

which type of input supply has been connected. The

state of the ACIN input can be read at any time by

reading the ACINSTAT[-] bit, where a value of 1

indicates that the voltage at ACIN is above the 1.2V

threshold (indicating that a wall-cube has been

attached), and a value of 0 indicates that the

voltage is below this threshold (indicating that ACIN

input is not valid and USB supply input is selected).

ACIN

CHGLEV

CHARGE CURRENT

(mA)

PRECONDITION CHARGE CURRENT

(mA)

450

ICHG/5

10% × ICHG

ICHG

10% × ICHG

Table 10:

ACIN and CHGLEV Inputs

ACT8934A Datasheet(PDF) 39 Page - Active-Semi, Inc

ACT8934A Datasheet(HTML) 39 Page - Active-Semi, Inc

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45

Datasheet Download

Link URL