MCP73831-2ACISLASHMC datasheet(15/28 Pages) MICROCHIP

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 2005-2014 Microchip Technology Inc.

DS20001984G-page 15

MCP73831/2

5.0

DETAILED DESCRIPTION

5.1

Analog Circuitry

5.1.1

BATTERY MANAGEMENT INPUT

SUPPLY (VDD)

The VDD pin is the input supply pin for the MCP73831/

2 devices. The MCP73831/2 automatically enter a

Power-Down mode if the voltage on the VDD input falls

below the UVLO voltage (VSTOP). This feature prevents

draining the battery pack when the VDD supply is not

present.

5.1.2

CURRENT REGULATION SET

(PROG)

Fast charge current regulation can be scaled by placing

a programming resistor (RPROG) from the PROG input

to VSS. The program resistor and the charge current

are calculated using the following equation:

The preconditioning trickle charge current and the

charge termination current are ratiometric to the fast

charge current based on the selected device options.

5.1.3

BATTERY CHARGE CONTROL

OUTPUT (VBAT)

The battery charge control output is the drain terminal

of an internal P-channel MOSFET. The MCP73831/2

provide constant current and voltage regulation to the

battery pack by controlling this MOSFET in the linear

region. The battery charge control output should be

connected to the positive terminal of the battery pack.

5.2

Digital Circuitry

5.2.1

STATUS INDICATOR (STAT)

The charge status output of the MCP73831 has three

different states: High (H), Low (L), and High-

Impedance (High Z). The charge status output of the

MCP73832 is open-drain. It has two different states:

Low (L) and High-Impedance (High Z). The charge sta-

tus output can be used to illuminate one, two or tri-color

LEDs. Optionally, the charge status output can be used

as an interface to a host microcontroller.

Table 5-1 summarizes the state of the status output

during a charge cycle.

5.2.2

DEVICE DISABLE (PROG)

The current regulation set input pin (PROG) can be

used to terminate a charge at any time during the

charge cycle, as well as to initiate a charge cycle or

initiate a recharge cycle.

Placing a programming resistor from the PROG input to

VSS enables the device. Allowing the PROG input to

float or by applying a logic-high input signal, disables

the device and terminates a charge cycle. When

disabled, the device’s supply current is reduced to

25 µA, typically.

REG

1000V

PROG

-----------------

Where:

RPROG

=kOhms

IREG

milliampere

TABLE 5-1:

STATUS OUTPUT

Charge Cycle State

STAT1

MCP73831 MCP73832

Shutdown

High Z

No Battery Present

High Z

Preconditioning

Constant-Current Fast

Charge

Constant Voltage

Charge Complete –

Standby

HHigh Z

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