RT5021 datasheet(42/67 Pages) RICHTEK

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RT5021

DS5021-01 April 2013

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

The Control Temperature Used in JEITA Operation

The above calculation gives R1 and R2. JEITA control thresholds for full charging current and 4.2V regulation voltage are

at TS/VP ratio = 32% and 52% (for TSSEL = L), 35% and 64% (for TSSEL = H). With the ratio, the corresponding NTC

thermistor resistances from the resistors in the voltage divider circuit can be obtained. According to the NTC resistances,

the corresponding temperatures can be found. The two temperatures are the control temperatures used in JEITA operation.

Operation State Diagram for TS Pin (TSSEL = H)

Any State

74% x VVP < VTS < 2.85V

Or VTS < 28% x VVP

Yes

VTS > 2.85V

Yes

TS fault State

ICHG = 0A

CHG 4Hz flash rate

Battery Remove State

ICHG = 0A

CHG 4Hz flash rate

Power Switch

For the charger, there are three power scenarios :

When a battery and an external power supply (USB or adapter) are connected simultaneously

If the system required load exceeds the input current limit, the battery will be used to supplement the current to the

load. However, if the system load is less than the input current limit, the excess power from the external power supply

will be used to charge the battery.

When only the battery is connected to the system

The battery provides the power to the system.

When only an external power supply is connected to the system

The external power supply provides the power to the system.

Input DPM Mode

For the charger, the input voltage is monitored when 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 further. This can prevent the IC from

damaging improperly configured or inadequately designed USB sources.

If VIN charger type is detected as SDP, the DPM function always is enabled.

For other types, the DPM function always is disabled but user can set A0.ENDPM to turn on the DPM function.

Enable the charger VIN DPM function. But if VIN charger type is detected as SDP

(CHG_TYP [2:0] = 000), the DPM function always is enabled.

0 : VIN DPM function disabled.

ENDPM

1 : VIN DPM function enabled.

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