Theory of Operation: Bluetooth 3-69
Figure 3-52. Detailed Low-Frequency Transmit/Receive Paths
3.5.1 Bluetooth Power
Our Bluetooth IC operates from a 3.6V (U6504, VBAT) switching regulator located on the VOCON
board to supply the Bluetooth IC core and a 1.85V (U6508, VDDS) supply for the I/O. It has a
shutdown (U2415 pin L3) that must be high for operation to work. The power-up/down sequence
required for operation is shown in Figure 3-53.
Figure 3-53. Chip Power-Up/Power-Down Sequence (Exernal Input/Output Shown)
32KHZ_3.3V
R2457M3
15K
C2475M3
1000PF
R2474M3
270K
O/P
NFC
ANTENNA
L2407M3
6.8 mH
1
C2457M3
18PF
U2412M3
NL17SZ02
R2475M3
150
USART1_TX
R2477M3
100K
7
16
15
R24
1
G1
R2476M3
100K
TC1_OCA
4
TX path
I/P
GPS_BT_3.3V
12
1
9
1
6
8
1
2
SCL
CL_DAT
DAT
SDO
XOUT
WARE
NC1
NC2
VCC
CS
SDI
XIN
LFN
LFP
VSS
GND
CTGND
C2465M3
1UF
U2403M3
AS3930
51009360002
11
13
5
4
3
RX path
NFC_CS_INV
C2454M3
220PF
1%
APX 5000/ APX 6000/
APX 6000XE/ SRX2200
Partial Current Tree
7.5V Batt
VDDS
VBAT
VDD1P8
RTC
Startup
CLK_REQ_POL
TCXO_CLK_REQ
VDD_TCXO
Hi Z - PD
Max 36.5 ms
5 ms
Analog PORz (~135 RTC cycles) +
Efuse shifting (~1000 RTC cycles)
Max time from clock request/
voltage to TCXO_CLK availability
Hi Z - PD
TCXO_CLK
REF_CLK_REQ
(OR of
nshutdown
pins)
<2.5ms
or