BCM43455 Preliminary Data Sheet
Bluetooth Power Management Unit
Figure 7 shows the startup signaling sequence prior to software download.
Figure 7: Startup Signaling Sequence Prior to Software Download
LPO
Host IOs unconfigured
Host IOs configured
VDDIO
T1
HostResetX
BT_DEV_WAKE
BT_REG_ON
T2
BTH IOs unconfigured
BTH IOs configured
T3
BT_HOST_WAKE
BT_UART_CTS_N
Host side drives this line
low
BT_UART_RTS_N
BTH device drives this line low
indicating transport is ready
T4
T5
CLK_REQ_OUT
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®
November 5, 2015 • 43455-DS109-R
Page 42
BROADCOM CONFIDENTIAL
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