Analog Devices ADP2291 Evaluation Board ADP2291RM-EVALZ ADP2291RM-EVALZ 数据表

ADP2291 

 

 

Rev. A | Page 14 of 20 

A typical application circuit is shown in Figure 22. The circuit is 
capable of a 750 mA charge current for an input voltage of 4.5 V 
to 6 V. Higher input voltages can be used, but the increased power 
dissipation of the pass device must be taken into account.  

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022

In some applications, the charger is required to terminate charg-
ing when the EOC threshold is reached. Automatic charger 
restart is not desired. Adding components R1, C1, and Q2 
terminates charging when the CHG pin opens and prevents 
further charging until the adapter is removed and reasserted.  

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In applications where the charge current needs to be selectable, 
use the circuit shown in Figure 24. This circuit allows a proces-
sor to determine if the charge current needs to be reduced due 
to an input source limitation or a different battery capacity 
option or simply to reduce the stress on the pass transistor.  
R2 and Q2 allow the charge current to be selected between 
high, which results in a charge current of 750 mA; and low, 
which results in a charge current of 250 mA.  

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In applications where the overall size must be small or the input 
voltage range is wide, adding thermal regulation is suggested. 
This allows the charger to monitor the temperature of the pass 
device and decrease the charge current as the temperature 
increases. By adding an NTC thermistor to the ADJ pin, it is 
possible to accomplish this; however, care is still required to 
ensure that the power dissipation of the pass device is not 
exceeded.  

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Some suggested NTC thermistor suppliers are listed in Table 6. 

BetaTHERM 

SMD2500KJ435J  

www.betatherm.com  

Murata  

NCP18WM474J  

www.murata .com  

Panasonic  

ERTJ0EV474J  

www.panasonic.com  

Vishay  

2322 615 1.474  

www.vishay.com