PRELIMINARY
CYW43340
Figure 7. Startup Signaling Sequence
LPO
Host I/Os
ƵŶconĮŐƵƌĞĚ
VDDIO
Host I/Os ĐŽŶĮŐƵƌĞĚ
BTH IOs
ƵncoŶĮŐƵƌĞĚ
BTH IOs ĐŽŶĮŐƵƌĞĚ
BT_REG_ON
BT_GPIO_1
(BT_HOST_WAKE)
TƐĞƩůĞ
T1
/ŶĚiĐĂƚĞƐ that BTH
ĚĞǀicĞ is ƌĞĂĚLJ.
BT_UART_RTS_N
BT_UART_CTS_N
T2
CLK_REQ
TƐĞƩůĞ
DƌiǀĞn
PƵůůĞĚ
EŽƚĞƐ͗ꢀꢀ
T1 is ƚŚĞ ƟŵĞ foƌ ƚŚĞ BTH ĚĞǀŝĐĞ to ƐĞƩůĞ its IOs aŌĞƌ a ƌĞƐĞƚ ĂŶĚꢀƌĞĨ ĐůŬ ƐĞƩůŝŶŐ ƟŵĞꢀĞůapsĞĚ.
T2 is ƚŚĞ ƟŵĞ foƌ ƚŚĞ BT ĚĞǀŝĐĞ to ĐŽŵƉůĞtĞ ŝŶŝƟĂůŝnjĂƟon ĂŶĚ ĚƌŝǀĞ BT_UART_RTS_N ůŽǁ͘
TƐĞƩůĞ is thĞ ƟŵĞ foƌ ƚŚĞ ƌĞf cůŬ siŐŶaů ĨƌŽŵ thĞ host to bĞ ŐƵaƌaŶƚĞĞĚ to haǀĞ ƐĞƩůĞĚ.
5.4.3 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 CYW43340 runs on the low-power
oscillator and wakes up after a predefined time period.
■ Alow-powershutdownfeatureallowsthedevicetobeturnedoffwhilethehostandanyotherdevicesinthesystemremainoperational.
When the CYW43340 is not needed in the system, the RF and core supplies are shut down while the I/O remains powered. This
allows the CYW43340 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.
During the low-power shut-down state, provided VDDIO remains applied to the CYW43340, all outputs are tristated, and most input
signals are disabled. Input voltages must remain within the limits defined for normal operation. This is done to prevent current paths
or create loading on any digital signals in the system and enables the CYW43340 to be fully integrated in an embedded device to take
full advantage of the lowest power-saving modes.
Two CYW43340 input signals are designed to be high-impedance inputs that do not load the driving signal even if the chip does not
have VDDIO power supplied to it: the frequency reference input (WRF_TCXO_IN) and the 32.768 kHz input (LPO). When the
CYW43340 is powered on from this state, it is the same as a normal power-up, and the device does not contain any information about
its state from the time before it was powered down.
Document Number: 002-14943 Rev. *L
Page 19 of 96
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