RT9480 datasheet(11/16 Pages) RICHTEK

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RT9480

DS9480-04

December 2014

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Application Information

The RT9480 is a high integrated IC for Li-Ion battery power

bank. This chip includes a linear charger, a synchronous

Boost, two output load management, LED indicator and

torch function.

Pre-Charge Mode

When the output voltage is lower than 2.3V, the charging

current will be reduced to a fast-charge current ratio to

protect the battery life time.

Fast-Charge Mode

When the output voltage is higher than 2.5V, the charging

current will be equal to the fast-charge current with 1.2A.

Constant-Voltage Mode

When the output voltage is near 4.2V or 4.35V, the charging

current will fall below the termination current.

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 4.05V or 4.2V, then

the charging current will resume again.

Charge Termination

When the charge current is lower than the charge

termination current ratio (10%) for VBAT > 4.05V or 4.2V

and the time is larger than the deglitch time (25ms), it will

be latched high unless the power is re-toggled.

Input DPM Mode

If the input voltage is lower than VDPM (4.5V), 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.

Temperature Regulation

In order to maximize charge rate, the RT9480 features a

junction temperature regulation loop. If the power

dissipation of the IC results in junction temperature greater

than the thermal regulation threshold (105

°C), the RT9480

will cut back on the charge current and disconnect the

battery in order to maintain thermal regulation at around

105

°C. This operation continues until the junction

temperature falls below the thermal regulation threshold

(105

°C) by the hysteresis level. This feature prevents the

maximum power dissipation from exceeding typical design

conditions.

Time Fault

The Fast-Charge Fault Time is set by 24hours.

When time fault happens, the charger cycle will be turned

off charging function.

Battery Pack Temperature Monitoring

The RT9480 features an external battery pack temperature

monitoring input. The TS input connects to the NTC

thermistor in the battery pack to monitor battery

temperature and prevent danger over temperature

conditions. If at any time the voltage at TS falls outside of

the operating range, charging will be suspended. The NTC

thermistor recommends using 10k

Ω.

JEITA Function

For JEITA battery temperature standard :

CV regulation voltage will change at the following battery

Temp ranges 45

°C to 60°C.

Synchronous Step-Up

The converter operates in fixed frequency PWM Mode

with 250kHz, Continuous Current Mode (CCM), and

Discontinuous Current Mode (DCM) with internal

MOSFETs.

4.35V or 4.2V

4.2V or 4.05V

100% Ichg

50% Ichg

010

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