SLUSDQ4 Data sheet

SLUSDQ4 April 2019 BQ79606A-Q1

PRODUCTION DATA.

8.5.1.4.2 Stack Device Wakeup and Hardware Shutdown

The daisy-chain interface is capable of sending/receiving three different tones. The first, WAKE, resets all settings of the BQ79606A-Q1 and transitions the device to active mode. The second, SLEEPtoACTIVE, only transitions the BQ79606A-Q1 to active mode (if the device in sleep mode) and does NOT reset any settings. The third, SHUTDOWN, transitions the device to shutdown mode. In SHUTDOWN Mode, only the WAKE tone is recognized, any SHUTDOWN or SLEEPtoACTIVE tones are ignored. Both WAKE and SLEEPtoACTIVE tones are accepted and propagated during SLEEP and ACTIVE modes. The SHUTDOWN tone is accepted in SLEEP and ACTIVE modes, but NOT propagated up the stack. In ACTIVE mode, SLEEPtoACTIVE causes no action, however, it is propagated up the stack. WAKE tones are sent out under 4 conditions: when a WAKE tone is received, when a WAKEUP pulse occurs on the WAKEUP pin, when a soft reset is commanded through CONTROL1[SOFT_RESET]=1 or when the CONTROL1[SEND_WAKE] bit is set. Similarly, SLEEPtoACTIVE tones are sent out when a SLEEPtoACTIVE tone is received, when a SLEEPtoACTIVE command is received from the UART (RX hold low for t_UART(StA)), or when the CONTROL1[SEND_SLPTOACT] bit is set. If a command to send a WAKE, SHUTDOWN, or SLEEPtoACTIVE tone is received while in the middle of sending a tone (WAKE, SHUTDOWN, or SLEEPtoACTIVE), the second command is ignored. A SHUTDOWN tone is only sent when the CONTROL1[SEND_SHUTDOWN] bit is set. It is only sent to the next device in the stack and is not propagated. The SHUTDOWN tone command is intended to be a last effort to reset a device that has become unresponsive to normal reset methods (SOFT-RESET or WAKE). Once the SHUTDOWN tone is received, the device immediately transitions to SHUTDOWN mode. Unlike base devices, the receivers and transmitters for stack devices are unaffected by the SHUTDOWN tone.

Table 24. Transition Table for Wake Tones on Stack Devices

Current State	WAKE Action	SLEEPtoACTIVE Action	SHUTDOWN Action
SHUTDOWN	Transition to ACTIVE, perform soft-reset, propagate WAKE up the stack	Ignored, not propagated up the stack	Ignored, not propagated up the stack
SLEEP	Transition to ACTIVE, perform soft-reset, propagate WAKE up the stack	Transition to ACTIVE, propagate SLEEPtoACTIVE up the stack	Transition to SHUTDOWN, not propagated up the stack
ACTIVE	Perform soft-reset, propagate WAKE up the stack	No action, but propagate SLEEPtoACTIVE up the stack	Transition to SHUTDOWN, not propagated up the stack

The tones are made up of bit-pair couplets (complementary bits, similar to the daisy chain communication) transmitted at a fixed frequency. WAKE couplets are logic '1', while SHUTDOWN and SLEEPtoACTIVE couplets are logic '0'. All tones are transmitted at t_COMTONE. WAKE tones are detected once n_WAKEDET WAKE couplets are received. Similarly, a SLEEPtoACTIVE tone is detected once n_SLPtoACTDET SLEEPtoACTIVE/SHUTDOWN couplets are received and a SHUTDOWN tone is detected once n_SDNDET SLEEPtoACTIVE/SHUTDOWN couplets are received. See Figure 30 for a graphical representation of the COM* tones.

Figure 30. Communication Tones