ADP3510ARU Просмотр технического описания (PDF) - Analog Devices

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производитель

ADP3510ARU

CDMA Power Management System

Analog Devices 

NONCHARGING

MODE

CHARGER DETECTED NO

CHRIN > BATSNS

YES

VBAT > UVLO

YES

NO

LOW CURRENT

CHARGE MODE

VSENSE = 15mV

BATTERY TYPE

NiMH

Li؉

CHGEN = HIGH

CHGEN = LOW

HIGH CURRENT

CHARGE MODE

VSENSE = 172mV

NiMH

CHARGING MODE

GATEIN = PULSED

NO

VBAT > 5.5V

NO

VBAT > 4.2V

YES

YES

NiMH

CHARGER OFF

GATEIN = HIGH

CONSTANT

VOLTAGE MODE

VBAT < 5.5V

NO

NO

END OF CHARGE

VSENSE < 12mV

YES

EOC = HIGH

YES

ADP3510

poll the battery to determine which chemistry is present and set

the charger to the proper mode.

Lithium Ion Charging

For lithium ion charging, the CHGEN input must be low. This

allows the ADP3510 to continue charging the battery at the full

current. The full charge current can be calculated by using:

172 mV

I = R CHR(FULL )

SENSE

(4)

If the voltage at BATSNS is below the charger’s output voltage of

4.2 V, the battery will continue to charge in the constant current

mode. If the battery has reached the final charge voltage, a con-

stant voltage is applied to the battery until the charge current has

reduced to the charge termination threshold. The charge termination

threshold is determined by the voltage across the sense resistor.

If the battery voltage is above 4.0 V and the voltage across the

sense resistor has dropped to 12 mV, then an end of charge signal

is generated and the EOC output goes high (see Figure 7).

The baseband processor can either let the charger continue to

charge the battery for an additional amount of time or terminate

the charging. To terminate the charging, the processor must

pull the GATEIN and CHGEN pins high.

4.2V

VBAT

3.2V

HIGH

CURRENT

ICHARGE

0

LOW

CURRENT

EOC

CURRENT

TERMINATE CHARGE

CHREN = HIGH

GATEIN = HIGH

Figure 6. Battery Charger Flowchart

Trickle Charging

When the battery voltage is below the UVLO threshold, the

charge current is set to the low current limit, or about 10% of

the full charge current. The low current limit is determined by the

voltage developed across the current sense resistor. Therefore,

the trickle charge current can be calculated by:

15 mV

I = R CHR(TRICKLE )

SENSE

(3)

Trickle charging is performed for deeply discharged batteries to

prevent undue stress on either the battery or the charger.

Trickle charging will continue until the battery voltage exceeds

the UVLO threshold.

Once the UVLO threshold has been exceeded, the charger will

switch to the high current limit, the LDOs will start up, and the

baseband processor will start to run. The processor must then

EOC

INDICATOR

Figure 7. Lithium Ion Charging Diagram

NiMH Charging

For NiMH charging, the processor must pull the CHGEN pin high.

This disables the internal Li+ mode control of the gate drive pin. The

gate drive must now be controlled by the baseband processor. By

pulling GATEIN high, the GATEDR pin is driven high, turning the

PMOS off. By pulling the GATEIN pin low, the GATEDR pin is

driven low, and the PMOS is turned on. So, by pulsing the GATEIN

input, the processor can charge a NiMH battery. Note that when

charging NiMH cells, a current limited adapter is required.

During the PMOS off periods, the battery voltage needs to be moni-

tored through the MVBAT pin. The battery voltage is continually

polled until the final battery voltage is reached. Then the charge

can either be terminated or the frequency of the pulsing reduced. An

alternative method of determining the end of charge is to monitor

the temperature of the cells and terminate the charging when a

rapid rise in temperature is detected.

REV. 0

–13–

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