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

The external power supply provides the power to the

system.

Input DPM Mode

For the RT9519A, the input voltage is monitored when

the USB100 or USB500 is selected. If the input voltage is

lower than VDPM, the input current limit will be reduced to

stop the input voltage from dropping any further. This can

prevent the IC from damaging improperly configured or

inadequately designed USB sources.

APPM Mode

Once the sum of the charging and system load currents

becomes higher than the maximum input current limit,

the SYS pin voltage will be reduced. When the SYS pin

voltage is reduced to the VAPPM, the RT9519A will

automatically operate in APPM mode. In this mode, the

charging current is reduced while the SYS current is

increased to maintain system output. In APPM mode,

the battery termination function is disabled.

Battery Supplement Mode Short Circuit Protect

In APPM mode, the SYS voltage will continue to drop if

the charge current is zero and the system load increases

beyond the input current limit. When the SYS voltage

decreases below the battery voltage, the battery will kick

in to supplement the system load until the SYS voltage

rises above the battery voltage.

While in supplement mode, there is no battery supplement

current regulation. However, a built in short circuit

protection feature is available to prevent any abnormal

current situations. While the battery is supplementing the

load, if the difference between the battery and SYS voltage

becomes more than the short circuit threshold voltage,

SYS will be disabled. After a short circuit recovery time,

tSHORT_R, the counter will be restarted. In supplement

mode, the battery termination function is disabled. Note

that for the battery supply mode exit condition, VBAT −

VSYS < 0V.

Thermal Regulation and Thermal Shutdown

The RT9519A provides a thermal regulation loop function

to monitor the device temperature. If the die temperature

rises above the regulation temperature, TREG, the charge

current will automatically be reduced to lower the die

temperature. However, in certain circumstances (such as

high VIN, heavy system load, etc.) even with the thermal

loop in place, the die temperature may still continue to

increase. In this case, if the temperature rises above the

thermal shutdown threshold, TSD, the internal switch

between VIN and SYS will be turned off. The switch

between the battery and SYS will remain on, however, to

allow continuous battery power to the load. Once the die

temperature decreases by ΔTSD, the internal switch

between VIN and SYS will be turned on again and the

device returns to normal thermal regulation.

Charging Profile

Battery Voltage

Charging Current

VPRECH

ICHG_PRE = 10% x ICHG_FAST

4.16 to 4.2 to 4.23V

-40 to 85°C

VRECH

If ISETL = H, ISETU = H

ISETL = L, ISETU = X

ITERMI = 10% x ICHG_FAST

If ISETL = H, ISETU = L

ITERMI = 3.3% x ICHG_FAST

ITERM

ITERM2

Time

Figure 2

www.richtek.com

12

DS9519A-02 April 2011

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