MCP73830 datasheet(10/22 Pages) MICROCHIP

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MCP73830/L

DS20005049D-page 10

 2011-2014 Microchip Technology Inc.

5.0

DETAILED DESCRIPTION

5.1

Undervoltage Lockout (UVLO)

An Internal Undervoltage Lockout (UVLO) circuit

monitors the input voltage and keeps the charger in

Shutdown mode until the input supply rises above the

UVLO threshold. In the event a battery is present when

the input power is applied, the input supply must rise

approximately 150 mV above the battery voltage

before the MCP73830/L devices become operational.

The UVLO circuit places the device in Shutdown mode

if the input supply falls to approximately 150 mV above

the battery voltage. The UVLO circuit is always active.

Any time the input supply is below the UVLO threshold,

or approximately 150 mV of the voltage at the VBAT pin,

the MCP73830/L devices are placed in Shutdown

mode.

5.2

Charge Qualification

When the input power is applied, the input supply must

rise 150 mV above the battery voltage before the

MCP73830/L becomes operational.

The automatic power-down circuit places the device in

Shutdown mode if the input supply falls to within

+50 mV of the battery voltage.

The automatic circuit is always active. Any time the

input supply is within +50 mV of the voltage at the

VBAT pin, the MCP73830/L is placed in Shutdown

mode.

For a charge cycle to begin, the automatic power-

down conditions must be met, and the charge enable

input must be above the input high threshold. The

battery voltage should be less than 96.5% of VREG.

5.2.1

BATTERY MANAGEMENT INPUT

SUPPLY (VDD)

The VDD input is the input supply to the MCP73830/L.

The MCP73830/L automatically enters Power-Down

mode if the voltage on the VDD input falls to within

+50 mV of the battery voltage. This feature prevents

draining the battery pack when the VDD supply is not

present.

5.2.2

BATTERY CHARGE CONTROL

OUTPUT (VBAT)

The battery charge control output is the drain terminal

of an internal P-channel MOSFET. The MCP73830/L

provides 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.

5.2.3

BATTERY DETECTION

The MCP73830/L device detects the battery presence

by monitoring the voltage at VBAT. The charge flow will

initiate when the voltage on VBAT is pulled below the

VRECHARGE threshold. Refer to Section 1.0 “Electri-

cal Characteristics” for VRECHARGE values. The value

will be the same for non-rechargeable devices.

When VBAT >VREG + Hysteresis, the charge will be

suspended or not started, depending on the condition,

to prevent the overcharge that may occur.

5.3

Preconditioning

If the voltage at the VBAT pin is less than the precondi-

tioning threshold, the MCP73830/L devices enter

Preconditioning mode. The preconditioning threshold

is factory set. Refer to Section 1.0 “Electrical Charac-

teristics” for preconditioning threshold options.

In this mode, the MCP73830/L devices supply 10% of

the fast charge current (established with the value of

the resistor connected to the PROG pin) to the battery.

When the voltage at the VBAT pin rises above the pre-

conditioning threshold, the MCP73830/L device enters

the Constant Current (Fast Charge) mode.

5.3.1

TIMER EXPIRED DURING

PRECONDITIONING MODE

If the internal timer expires before the voltage threshold

is reached for Fast Charge mode, a timer fault is

indicated, and the charge cycle terminates. The

MCP73830/L devices remain in this condition until the

battery is removed, the input power is cycled, or CE is

toggled. If the battery is removed, the MCP73830/L

devices enter Standby mode, where they remain until a

battery is reinserted.

Note:

The MCP73830/L devices also offer

options with no preconditioning.

Note:

The typical preconditioning timers for the

MCP73830/L are 60 minutes.

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