RT9527 查看數據表（PDF） - Richtek Technology

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比赛名单

RT9527

Single Cell Li-Ion Battery Charger with Adjustable Charging Current for Portable Applications

Richtek Technology 

RT9527

Battery Connect Reverse

If battery is connected reversely, it causes that the voltage

of BAT pin is negative. RT9527 will disable charger function

until battery voltage is normal.

Temperature Regulation

In order to maximize charge rate, the RT9527 features a

junction temperature regulation loop. If the power

dissipation of the IC results in junction temperature greater

than the thermal regulation threshold (125°C), the RT9527

will cut back on the charge current and disconnect the

battery in order to maintain thermal regulation at around

125°C. This operation continues until the junction

temperature falls below the thermal regulation threshold

(125°C) by the hysteresis level. This feature prevents the

maximum power dissipation from exceeding typical design

conditions.

Sleep mode

The RT9527 enters sleep mode if both the AC and USB

ports are removed from the input. This feature prevents

draining the battery during the absence of an input supply.

Battery Pack Temperature Monitoring

The RT9527 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

timers maintain their values but suspend counting. When

charging is suspended due to a battery pack temperature

fault, the CHG pin remains low and continues to indicate

charging.

VIN

Too Cold +

NTC_fault

-

+

Too Hot

-

RT1

TS

RNTC RT2

R T2

=

310RTCRTH

117RTC  427RTH

R T1

=

7RTHRT2

3RTH  RT2 

Time Fault

The Fast-Charge Fault Time is set according to the following

equations :

Fast-Charge Fault Time : tFCHG = 14400 x CTIMER (s)

Pre-Charge Fault Time : tPCHG = 1 / 8 x tFCHG (s)

where the CTIMER unit is in μF.

When time fault happens, the charger cycle will be turned

off and the CHG pin will become high impedance.

Thermal Considerations

For continuous operation, do not exceed absolute

maximum junction temperature. The maximum power

dissipation depends on the thermal resistance of the IC

package, PCB layout, rate of surrounding airflow, and

difference between junction and ambient temperature. The

maximum power dissipation can be calculated by the

following formula :

PD(MAX) = (TJ(MAX) − TA) / θJA

where TJ(MAX) is the maximum junction temperature, TA is

the ambient temperature, and θJA is the junction to ambient

thermal resistance.

For recommended operating condition specifications, the

maximum junction temperature is 125°C. The junction to

ambient thermal resistance, θJA, is layout dependent. For

WDFN-8L 2x2 package, the thermal resistance, θJA, is

120°C/W on a standard JEDEC 51-7 four-layer thermal

test board. The maximum power dissipation at TA = 25°C

can be calculated by the following formula :

PD(MAX) = (125°C − 25°C) / (120°C/W) = 0.833W for

WDFN-8L 2x2 package

The maximum power dissipation depends on the operating

ambient temperature for fixed TJ(MAX) and thermal

resistance, θJA. The derating curve in Figure 1 allows the

designer to see the effect of rising ambient temperature

on the maximum power dissipation.

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

DS9527-02 May 2014

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

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