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LPO
VDDIO
HostResetX
BT_GPIO_0
(BT_DEV_WAKE)
BT_REG_ON
BT_GPIO_1
(BT_HOST_WAKE)
BT_UART_CTS_N
BT_UART_RTS_N
CLK_REQ_OUT
Notes :
x T
is the time for the host to settle its IOs after a reset.
1
x T
is the time for the host to drive BT_REG_ON high after the host IOs are configured.
2
x T
is the time for the BTH device to settle its IOs after a reset and the reference clock settling time has elapsed.
3
x T
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
4
the BTH device has completed initialization.
x T
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
5
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.
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 oper-
■
ational. When the CYW43353 is not needed in the system, the RF and core supplies are shut down while the I/O remains pow-
ered. 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.
Document Number: 002-14949 Rev. *G
PRELIMINARY
Figure 5. Startup Signaling Sequence
Host IOs
unconfigured
Host IOs configured
T
1
T
2
T
5
BTH IOs
BTH IOs configured
unconfigured
T
3
T
4
CYW43353
Host drives
this low.
BTH device drives this
low indicating
transport is ready.
Driven
Pulled
Page 24 of 113
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