SLUSDQ4 April 2019 BQ79606A-Q1
The WAKEUP input pin is used to wake up and reset the base device from SLEEP or SHUTDOWN mode. Additionally, the WAKEUP input defines a "base" device. The WAKEUP input pin is monitored continuously for a low pulse of at least tHLD_WAKE (but shorter than tHLD_SD) followed by driving the input high. The command is accepted after WAKEUP is high for 30us. This high-low-high (1-0-1) transition (WAKE pulse) signals the BQ79606A-Q1 to enter ACTIVE mode. When a valid WAKEUP signal is received, all settings are reset to the OTP programmed values and the device enters ACTIVE mode and sends a WAKE tone up the stack. If already in ACTIVE mode, the settings are reset and the WAKE tone is sent up the stack. If a command to send a WAKE or SLEEPtoACTIVE tone is received while in the middle of sending a tone (WAKE or SLEEPtoACTIVE), the second command is ignored.
WAKEUP pin must be pulled up to VIO for a base device (for stack devices, connect WAKEUP pin to AVSS). When the IC exits a RESET condition (either through a software RESET, or receiving a WAKE pulse), the WAKEUP pin is sampled. If WAKEUP is high, the device is recognized as a "base" device and disables the COML receiver. This prevents an infinite communication loop when using the ring architecture.
The RX input pin of the UART interface is used to send a SLEEPtoACTIVE signal to the base device of a stack. Hold RX low for tUART(StA) to send a SLEEPtoACTIVE signal. When a valid SLEEPtoACTIVE signal is received in SLEEP mode, the BQ79606A-Q1 transitions to ACTIVE mode without resetting its parameters and sends a SLEEPtoACTIVE tone up the stack. Additionally, a communication clear is detected to clear the bus for new communication traffic. When a SLEEPtoACTIVE signal is received in ACTIVE mode, the BQ79606A-Q1 does not perform any action other than the communication clear and sending a SLEEPtoACTIVE tone up the stack. SLEEPtoACTIVE is ignored in SHUTDOWN Mode. COMM_FAULT errors when sending a SLEEPtoACTIVE signal to the base device due to the communication clear. See Communication Clear (Break) Detection for details.
In addition to waking up the device, the WAKEUP input pin is used to send the device to SHUTDOWN mode when it does not respond to a normal reset command (either through the UART or WAKEUP). To send a HARDWARE SHUTDOWN command using WAKEUP pin, drive WAKEUP pin low for tHLD_SD followed by driving it high. The command is accepted after WAKEUP is high for 30us. Upon receiving the SHUTDOWN, the IC immediately enters SHUTDOWN mode. The next time the IC receives a WAKEUP command, it enters ACTIVE mode with the COMH and COML receivers and the COML transmitter are disabled (COMH transmitter is the only one that is enabled). This allows the base device to reject any communication from the stack while it is attempting to be re-initialized. The host must re-enable the necessary receivers before resuming normal operation.
After the wakeup or a shutdown pulse is received on the WAKEUP pin, the user should wait for the device to fully wake up (tSU(WAKE)) or fully shutdown (tSDorSLP) before sending another pulse in that pin.
Stack devices (devices communicating over the daisy chain only) must connect WAKEUP pin to AVSS to avoid being mis-recognized as a base device.
When a WAKE or SLEEPtoACTIVE command is sent, the host MUST wait for the device to fully wake up ( tSU(WAKE) ) before sending additional WAKE, shutdown, or SLEEPtoACTIVE command. Failure to do so may result the device to enter unknown state.
|Current State||WAKE Pulse (1-0-1 on WAKEUP pin)||SLEEPtoACTIVE Signal on RX Pin|
|SHUTDOWN||Transition to ACTIVE, perform soft-reset, propagate WAKE tone to the stack devices||Ignored, not propagated up the stack|
|SLEEP||Transition to ACTIVE, perform soft-reset, propagate WAKE tone to the stack devices||Transition to ACTIVE, propagate SLEEPtoACTIVE tone to the stack devices|
|ACTIVE||Perform soft-reset, propagate WAKE tone to the stack devices||No action, but propagate SLEEPtoACTIVE tone to the stack devices|