Document No. 002-14949 Rev. *E
Page 24 of 113
PRELIMINARY
CYW43353
Figure 5. Startup Signaling Sequence
5.5.3 BBC Power Management
The following are low-power operations for the BBC:
■
Physical layer packet-handling turns the RF on and off dynamically within transmit/receive packets.
■
Bluetooth-specified low-power connection modes: sniff, hold, and park. While in these modes, the CYW43353 runs on the
low-power oscillator and wakes up after a predefined time period.
■
A low-power shutdown feature allows the device to be turned off while the host and any other devices in the system remain
operational. When the CYW43353 is not needed in the system, the RF and core supplies are shut down while the I/O
remains powered. This allows the CYW43353 to effectively be off while keeping the I/O pins powered so they do not draw
extra current from any other devices connected to the I/O.
HostResetX
VDDIO
LPO
BT_GPIO_0
(BT_DEV_WAKE)
BT_UART_CTS_N
CLK_REQ_OUT
BT_GPIO_1
(BT_HOST_WAKE)
BT_REG_ON
BT_UART_RTS_N
Host IOs configured
Host IOs
unconfigured
BTH IOs configured
BTH IOs
unconfigured
T
4
T
5
T
3
T
2
T
1
Notes :
x
T
1
is the time for the host to settle its IOs after a reset.
x
T
2
is the time for the host to drive BT_REG_ON high after the host IOs are configured.
x
T
3
is the time for the BTH device to settle its IOs after a reset and the reference clock settling time has elapsed.
x
T
4
is the time for the BTH device to drive BT_UART_RTS_N low after the host drives BT_UART_CTS_N low. This assumes
the BTH device has completed initialization.
x
T
5
is the time for the BTH device to drive CLK_REQ_OUT high after BT_REG_ON goes high. The CLK_REQ_OUT pin is used
in designs that have an external reference clock source from the host. It is irrelevant on clock-based designs where the
BTH device generates its own reference clock from an external crystal connected to its oscillator circuit.
x
The timing diagram assumes that VBAT is present.
Driven
Pulled
Host drives
this low.
BTH device drives this
low indicating
transport is ready.