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Backup Battery

 

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Many Toradex Carrier Boards contain a holder for a backup battery. It is used to keep the RTC powered for uninterrupted timekeeping while primary power is disconnected.

The following carrier boards use the listed battery types:

CoM Family Carrier Board Battery Notes
Apalis Apalis Evaluation Board CR2032 Select between powering the Internal & External RTC using JP22
Apalis Ixora Carrier Board CR1225 Connected to External RTC. Internal RTC may be powered by removing R40 and assembling R39
Colibri Colibri Evaluation Board CR2032 Select between powering the Internal & External RTC using JP23
Colibri Iris Carrier Board CR1225 Connected to External RTC
Colibri Viola Carrier Board CR1225 The battery holder is not assembled on V1.0A Viola Carrier Boards
Colibri Orchid Carrier Board CR2032

Battery Circuit

Refer to the following articles for details regarding each CoM family's backup battery characteristics:

CoM Family Relevant Article
Apalis VCC_BACKUP
Colibri VCC_BATT

In general, the following circuitry is recommended for uninterrupted power supply of the RTC utilizing a non-rechargeable battery:


Some modules provide battery charging functionality. Therefore, when using a single non-rechargeable voltage source, the inline diode and resistor will still be required to protect the supply from reverse current. A FET may also be used for reverse current protection. Take care to ensure the circuit's reverse leakage current is low enough for safe operation with the chosen battery/power supply. High quality and/or redundant diodes should be used to safeguard against component failure which could result in battery fire/explosion.

Battery Charging

Although not standard for all Toradex modules, battery charging is a feature of some modules. The following table identifies module battery charging characteristics:

Module Charge Current (mA) Voltage Range (V) PMIC Control Register
Apalis iMX6 0.06 2.5-3.3 COINCTL
Apalis T30 0.65 2.5-VBAT BBCH_REG
Colibri T30 0.65 2.5-VBAT BBCH_REG
Colibri T20 20 2.5-3.3 SUPPLYV4,SUPPLYV6
Colibri VF61 tbd ~3 -
Colibri VF50 tbd ~3 -