ACT8810
Active- Semi
Rev 4, 01-Oct-09
RTC LOW-DROPOUT LINEAR REGULATOR
FUNCTIONAL DESCRIPTION
Backup Battery Charging
General Description
REG6 features a constant current-limit, which
REG6 is an always-on, low-dropout linear regulator
(LDO) that is optimized for RTC and backup-battery
applications. REG6 features low-quiescent supply
current, current-limit protection, and reverse-current
protection, and is ideally suited for always-on power
supply applications, such as for a real-time clock, or
as a backup-battery or super-cap charger.
protects the IC under output short-circuit conditions
as well as provides a constant charge current, when
operating as a backup battery charger.
As shown in Figure 10, REG6 features a CC/CV
output characteristic, regulating its output voltage
for load currents up to 30mA, and regulating output
current when the load exceeds (typically) 60mA.
Output Voltage
Figure 10:
By default, REG6's output voltage is as defined in
the Ordering Information section. However, this
voltage may be programmed by writing to the
REG6CFG/VSETx[ ] register via the I2C interface.
REG6 Output Voltage
REG6 Output Voltage vs. Load Current
4
Reverse-Current Protection
REG6 features internal circuitry that limits the
reverse supply current to less than 1µA when the
input voltage falls below the output voltage, as can
be encountered in backup-battery charging
applications. REG6's internal circuitry monitors the
input and the output, and disconnects internal
circuitry and parasitic diodes when the input voltage
falls below the output voltage, greatly minimizing
backup battery discharge.
3
2
Constant Voltage Region
Constant Current Region
1
0
0
20
40
60
80
100
Typical Application
Load Current (mA)
Voltage Regulators
REG6 is ideally suited for always-on voltage-
regulation applications, such as for real-time clock
and memory keep-alive applications. This regulator
requires only a small ceramic capacitor with a
minimum capacitance of 1μF for stability. For best
performance, the output capacitor should be
connected directly between the output and GA, with
a short and direct connection.
Figure 9:
Typical Application of RTC LDO
OUT6
ACT8810
RTC
Supper cap or
Back-up battery
Innovative PowerTM
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