SC14480 データシートの表示（PDF） - Unspecified

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SC14480

1.8V Single Chip for DECT

Unspecified 

4.1 CHARGE CONTROL

The SC14480A5M, SC14480A2M6 contains a con-

stant voltage, constant current charging control circuit.

The intended applications are depicted in the applica-

tion diagrams.

See also “AN-D-139 SC14480 power management”

The charge circuit has two modes of operation:

• Continuous current/voltage source mode. The con-

trol circuit keeps the charge voltage or the charge

current equal to the defined values (whichever of the

two is reached first). The values can be changed via

BAT_CTRL2_REG. This mode is used when the

charger supply adapter has low output resistance.

• On/off mode (SC1443x compatible mode). In case of

charging via an adapter with significant output

resistance, it is also possible to use the external

pass transistor as a switch. When the charge current

is set to “unlimitted”, a small hysteresis is added to

the charge voltage and the external transistor is

either completely open or completely closed. This

will significantly reduce the dissipated power in the

external transistor (excessive power is now dissi-

pated in the output resistance of the adapter).

The charging control circuit is initially supplied from the

l CHARGE-pin (after start-up, VBAT will take over). The

complete charging circuit is powered down if the

tia CHARGE pin is low for more than 10ms or by setting

the BAT_CTRL2_REG[CHARGER_ON]=0. In Li-ion

application, the charger is also disabled if the voltage

on the NTC pin is in “too hot” region. (See "Charger

n Auto shut off circuit" on page 26)

e Non rechargable batteries

fid To check for non-rechargable batteries,

BAT_CTRL2_REG[bit0] bit is set to ‘1’ (the charge volt-

age is increased above normal levels) and an ADC

conversion can be started. As soon as the conversion

n is ready, BAT_CTRL2_REG[bit0] is automatically reset

to 0 (see Table 79) in order to return to normal charge

o voltages.

C Charge status

If a charger voltage on pin CHARGE pin is high, the

CHARGE_STS in BAT_STATUS_REG (0xFF4816) is

set to 1. The software has to reset this bit. The actual

value of the CHARGE pin can be read from the

P1_DATA_REG.

Charge regulator used as general purpose LDO in

basestation

In basestation applications the charge circuit can be

used as general purpose LDO. See applicatin dia-

grams. The output voltage is set with the

BAT_CTRL2_REG[CHARGE_LEVEL] bits. Vinput

ranges depend on the “output voltage” and maximum

dissipation of the PNP transistor.

In this application the SOC circuit is used to regulate

the start-up current. After start-up the

BAT_CTRL2_REG[CHARGE_CUR] bits have no effect

anymore.

© 2008-2009 SiTel Semiconductor

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Version: January 21, 2009 v1.0

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