SLUUCG7 April 2024 BQ76922
The REG1 LDO in the BQ76922 device is for customer use, and its output voltage can be programmed to 1.8V, 2.5V, 3.0V, 3.3V, or 5.0V. The voltage level is selected using the Settings:Configuration:REG1 Config[REG1V_2:REG1V_0] configuration bits as shown below. The LDO is enabled using the Settings:Configuration:REG1 Config[REG1_EN] configuration bit, and its setting can be modified during operation using the 0x0098 REG1_CONTROL() subcommand. This subcommand takes an 8-bit value that matches the bits in the Settings:Configuration:REG1 Config configuration register. It is important that the voltage selection not be changed in CONFIG_UPDATE mode while the LDO is enabled.
REG1V_2:0 | REG1 Voltage (V) |
---|---|
0x0 - 0x3 | 1.8 |
0x4 | 2.5 |
0x5 | 3.0 |
0x6 | 3.3 |
0x7 | 5.0 |
The BQ76922 OTP is programmed in the TI factory to enable the REG1 LDO and REG0 pre-regulator, with the REG1 voltage set to 3.3V. Thus, when the device is initially powered from SHUTDOWN mode, the REG1 and REG0 regulators will be powered as well. If REG1 is disabled, the LDO output is pulled to VSS with an internal resistance of ≅2.5-kΩ. If the pullup resistors for the serial communications are connected to the REG1 voltage output and it is disabled on the manufacturing line, the REG1 voltage can be overdriven from an external voltage supply, to allow communications with the device. The BQ76922 device can then be programmed to enable REG0 and REG1 with the desired configuration, and this setting can be programmed into OTP memory. Thus, at each later power-up, the device will autonomously load the OTP settings and enable the LDO as configured, without requiring communications first.