ACT8810 datasheet(39/54 Pages) ACTIVE-SEMI

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RTC LOW-DROPOUT LINEAR REGULATOR

ACT8810

Rev 9, 15-Nov-12

Innovative Power

- 39 -

www.active-semi.com

ActivePMU

TM and ActivePathTM are trademarks of Active-Semi.

2CTM is a trademark of NXP.

General Description

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.

Output Voltage

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.

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

encountered

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.

Typical Application

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

Backup Battery Charging

REG6 features a constant current-limit, which

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.

Figure 10:

REG6 Output Voltage

FUNCTIONAL DESCRIPTION

REG6 Output Voltage vs. Load Current

Constant Voltage Region

Constant Current Region

Load Current (mA)

100

ACT8810

RTC

Supper cap or

Back-up battery

OUT6

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