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 |
|---|---|
| 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.
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 | - |
