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|
Refer to the following articles for details regarding each CoM family's backup battery characteristics:
|CoM Family||Relevant Article|
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.
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|