RCM2000 datasheet(68/80 Pages) DIGI

68 / 80 page

RabbitCore RCM2000

The drain on the battery by the RCM2000 is typically 10 µA when no other power is sup-

plied. If a 950 mA·h battery is used, the battery can last more than 6 years:

Since the shelf life of the battery is 10 years, the battery can last for its full shelf life. The

actual life in your application will depend on the current drawn by components not on the

RCM2000 and the storage capacity of the battery.

C.1.2 Battery-Backup Circuit

The battery-backup circuit serves three purposes:

•

It reduces the battery voltage to the SRAM and to the real-time clock, thereby limiting

the current consumed by the real-time clock and lengthening the battery life.

•

It ensures that current can flow only out of the battery to prevent charging the battery.

•

A voltage, VOSC, is supplied to U5, which keeps the 32.768 kHz oscillator working

when the voltage begins to drop.

VRAM and Vcc are nearly equal (<100 mV, typically 10 mV) when power is supplied to

the RCM2000.

Figure C-2 shows the RCM2000 battery-backup circuit.

Figure C-2. RCM2000 Battery-Backup Circuit

VRAM is also available on pin 34 of header J2 to facilitate battery backup of the external

circuit. Note that the recommended minimum resistive load at VRAM is 100 k

Ω, and new

battery life calculations should be done to take external loading into account.

950 mA·h

10 µA

------------------------

10.8 years (shelf life = 10 years).

R11

10 kW

VRAM

VBAT-EXT

External Battery

R12

47 kW

2 kW

R14

RT1

22 kW

mPBAT

Vcc

22 kW

47 kW

pin 5

thermistor

C19

1 nF

RCM2000 Datasheet(PDF) 68 Page - Digi International Inc.

RCM2000 Datasheet(HTML) 68 Page - Digi International Inc.

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