MCP73213 datasheet(17/34 Pages) MICROCHIP

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DS22190A-page 17

MCP73213

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 MCP73213 device 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.

At any time, the input supply is below the UVLO

threshold or approximately 150 mV of the voltage at the

VBAT pin, the MCP73213 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

typical 13V, OVP threshold. The hysteresis of OVP is

approximately 150 mV for the MCP73213 device.

The MCP73213 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

MCP73213 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 MCP73213 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 MCP73213.

The MCP73213 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 MCP73213

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.

5.3.3

BATTERY DETECTION

The MCP73213 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

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 start, 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 MCP73213 device

enters a preconditioning mode. The preconditioning

threshold

factory

set.

Refer

Section 1.0

“Electrical

Characteristics”

for

preconditioning

threshold options.

In this mode, the MCP73213 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

preconditioning threshold, the MCP73213 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

MCP73213 device remains in this condition until the

battery is removed or input power is cycled. If the

battery is removed, the MCP73213 device enters the

Stand-by mode where it remains until a battery is

reinserted.

Note:

The MCP73213 device also offers options

with no preconditioning.

Note:

The

typical

preconditioning

timer

for

MCP73213 is 32 minutes. The MCP73213

also offers options with no preconditioning

timer.

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