MCP73113 datasheet(17/34 Pages) MICROCHIP

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DS22183C-page 17

MCP73113/4

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 MCP73113/4 device becomes 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.

At any time, the input supply is below the UVLO

threshold or approximately 150 mV of the voltage at the

VBAT pin, the MCP73113/4 device is placed in a

shutdown mode.

5.2

Overvoltage Protection (OVP)

An internal overvoltage protection (OVP) circuit

monitors the input voltage and keeps the charger in

shutdown mode when the input supply rises above the

OVP

threshold.

The

hysteresis

OVP

approximately 150 mV for the MCP73113/4 device.

The MCP73113/4 device is operational between UVLO

and OVP threshold. The OVP circuit is also recognized

as overvoltage lock out (OVLO).

5.3

Charge Qualification

When the input power is applied, the input supply must

rise 150 mV above the battery voltage before the

MCP73113/4 becomes operational.

The automatic power down circuit places the device in

a shutdown mode if the input supply falls to within

+50 mV of the battery voltage.

The automatic circuit is always active. At any time the

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

VBAT pin, the MCP73113/4 is placed in a 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.

5.3.1

BATTERY MANAGEMENT INPUT

SUPPLY (VDD)

The VDD input is the input supply to the MCP73113/4.

The MCP73113/4 automatically enters a 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.

5.3.2

BATTERY CHARGE CONTROL

OUTPUT (VBAT)

The battery charge control output is the drain terminal

of an internal P-channel MOSFET. The MCP73113/4

devices

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.

5.3.3

BATTERY DETECTION

The MCP73113/4 detects the battery presence with

charging of the output capacitor. The charge flow will

initiate when the voltage on VBAT is pulled below the

VRECHARGE threshold. Refer to Section 1.0 “Electrical

Characteristics” for V

RECHARGE values. The value will

be the same for non-rechargeable device.

When VBAT > VREG + Hysteresis, the charge will be

suspended or not started, depends on the condition to

prevent over charge that may occur.

5.4

Preconditioning

If the voltage at the VBAT pin is less than the

preconditioning threshold, the MCP73113/4 device

enters a preconditioning mode. The preconditioning

threshold is factory set. Refer to

Section 1.0

“Electrical

Characteristics”

for

preconditioning

threshold options.

In this mode, the MCP73113/4 device supplies 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 MCP73113/4 device

enters the constant current (fast charge) mode.

5.4.1

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

MCP73113/4 device remains in this condition until the

battery is removed or input power is cycled. If the

battery is removed, the MCP73113/4 device enters the

standby mode where it remains until a battery is

reinserted.

Note:

The MCP73113/4 also offer options with

no preconditioning.

Note:

The

typical

preconditioning

timer

for

MCP73113/4

minutes.

The

MCP73113/4 also offer options with no

preconditioning timer.

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