RT9519A Просмотр технического описания (PDF) - Richtek Technology

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RT9519A

Linear Single Cell Li-lon Battery Charger with Auto Power Path Management

Richtek Technology 

RT9519A

Applications Information

The RT9519A is a fully integrated single-cell Li-ion battery

charger ideal for portable applications. The internal thermal

feedback circuitry regulates the die temperature to optimize

the charge rate for all ambient temperatures. Other features

include under voltage protection and over voltage

protection.

Pre-charge Mode

When the output voltage is lower than 2.8V, the charging

current will be reduce to a fast-charge current ratio set by

RISETA to protect the battery life time.

Fast-charge Mode

When the output voltage is higher than 3V, the charging

current will be equal to the fast-charge current set by

RISETA.

Constant Voltage Mode

When the output voltage is near 4.2V, and the charging

current fall below the termination current, after a deglitch

time check of 25ms, the charger will become disabled

and CHG will go from L to H.

Re-charge Mode

When the chip is in charge termination mode, the charging

current will gradually go down to zero. However, once the

voltage of the battery drops to below 4.1V, there will be a

deglitch time of 100ms and then the charging current will

resume again.

Charging Current Decision

The charge current can be set according to the following

equations :

If ISET = H (for ICHG1)

ICHG_FAST

=

VISETA

RISETA

× 300

If ISET = L (for ICHG2 )

ICHG_FAST

=

VISETA

RISETA

×150

ICHG_PRE = 10%×ICHG_FAST

Time Fault

During the fast charge phase, several events may increase

the charging time.

For example the system load current may have activated

the APPM loop which reduces the available charging

current. the device has entered thermal regulation because

the IC junction temperature has exceeded TREG.

During each of these events, if 3V < VBAT < 4.1V, the

internal charging time is slowed down proportionately to

the reduction in charging current. However, once the

duration exceed the fault time, the CHG output will flash

at approximately 2Hz to indicate a fault condition and the

charge current will be reduced to about 1mA.

tFCHG_true

=

tFCHG

×

2V

VISETA

tFCHG_true : modified timer in fast

tFCHG : original timer in fast charger

t FCHG

=

14400

sec × ( CTIMER

1μF

)

t PCHG

=

tFCHG

8

tPCHG : timer in pre-charge

Time fault release methods :

(1) Re-plug power

(2) Toggle EN

(3) Enter/exit suspend mode

(4) Remove Battery

(5) OVP

Note that the fast charge fault time is independent of the

charge current.

Power Good

VIN Power Good ( PGOOD = L)

Input State

VIN < VUVLO

VUVLO < VIN < VBAT + VOS_H

VBAT + VOS_H < VIN < VOVP

VIN > VOVP

PGOOD Output

High Impedance

High Impedance

Low Impedance

High Impedance

www.richtek.com

10

DS9519A-02 April 2011

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