BCM4354 Data Sheet
Bluetooth Power Management Unit
The timing for the startup sequence is defined in Figure 6.
Figure 6: Startup Signaling Sequence
LPO
VDDIO
Host I/Os
unconfigured
Host I/Os
configured
HostResetX
T1
BT_GPIO_0
(BT_DEV_WAKE
)
BTH I/Os
unconfigured
T2
BT_REG_ON
BTH I/Os
configured
BT_GPIO_1
(BT_HOST_WAKE)
T3
Host side drives
this line low
BT_UART_CTS_N
BTH device drives this line low
indicating transport is ready
T4
BT_UART_RTS_N
CLK_REQ_OUT
T5
Driven
Pulled
Notes:
T1 is the time for Host to settle it’s IOs after a reset.
T2 is the time for Host to drive BT_REG_ON high after the Host IOs are configured.
T3 is the time for BTH (Bluetooth) device to settle its IOs after a reset and reference clock settling time has elapsed.
T4 is the time for BTH device to drive BT_UART_RTS_N low after the Host drives BT_UART_CTS_N low. This assumes the BTH device has already
completed initialization.
T5 is the time for BTH device to drive CLK_REQ_OUT high after BT_REG_ON goes high. Note this pin is used for designs that use an external reference
clock source from the Host. This pin is irrelevant for Crystal reference clock based designs where the BTH device generates it’s own reference clock from
an external crystal connected to it’s oscillator circuit.
Timing diagram assumes VBAT is present.
Broadcom®
October 15, 2014 • 4354-DS109-R
Page 38
BROADCOM CONFIDENTIAL
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