Kenwood NX-5300 Service Manual page 20

2.4.9 Bluetooth/GPS Circuit
The main component of the BT/GPS circuit is BT/GPS IC (IC850).
The clocks of BT/GPS IC require 19.2MHz for core and 32.768kHz slow clock (X850) for UART.
19.2MHz clock (X700) is shared with MPU/DSP (IC702), and is supplied through the clock buffer IC (IC700).
The BT/GPS IC communicates to the MPU/DSP (IC702) on the HCI UART. Interface of UART & Digital audio (PCM) between the
MPU/DSP (IC702) and the BT/GPS IC (IC850), have level conversion at the level conversion IC (IC852, IC853).
The BT/GPS IC is powered by 1.8V and 3.3V which are supplied from two discrete external regulators (IC38 and IC37). The input of
these regulators is sourced from a switching regulator (IC33) which regulates the battery voltage to 3.8V.
GPS antenna
Matching
HPF
BT antenna
2.4.9.1 Bluetooth Circuit
The BT/GPS IC (IC850) support Bluetooth 3.0 up to HCI level.
The TX/RX frequency is 2400-2483.5MHz (79ch Hopping, 2402-2480MHz, 1MHz step). The transmit power is +2dBm at Bluetooth
antenna input.
The Bluetooth antenna is made of sheet metal, and connected to the BT/GPS IC (IC850) through the LC filter (L855).
Frequency configuration for Bluetooth is following:
There are two LO modes: 2X and Offset LO (OSLO). 2X where LO is 2*RF_FREQ (e.g. when transmitting at 2441MHz it is at
4882MHz). OSLO where LO is at 2/3*RF_FREQ (e.g. when transmitting at 2441MHz it is at 1627.333MHz).
In RX the 2X is always used.
In GFSK TX if power is 10dBm or more then OSLO is used.
In EDR2 TX if power is -12dBm or more then OSLO is used.
In EDR3 TX if power is -12dBm or more then OSLO is used.
Otherwise 2X is used for TX as well.
MPU/DSP
X700
TCXO
19.2MH
1-20 (No.RA015<Rev.002>)
LNA Supply
LNA Enable
Pre-SAW LNA
LC filter
Fig.5 Bluetooth/GPS circuit
IC702 IC852
UART
Level
Conversion
IC853
PCM
Level
Conversion
IC700
Clock
Buffer
Fig.6 Bluetooth circuit
IC850
VDD_TCXO(G1)
GPS_EXT_LNA_EN(H6)
GPS IC(IC850)
GPS_LNA_IN(L2)
Attenuator Post-SAW
BTFM_nSHUTDOWN(A6)
IC700
TCXO Clock
TCXO_CLK_LV(F1)
19.2MHz Buffer
BT_RF
IC850
UART
L855
LC
BT/GPS
Filter
IC
PCM
X850
32.768kHz
Clock
BT/GPS IC
VBAT1(A2)
3.3V
TCXO_LDO_IN(H1)
1.8V
VDDS
GPS_TX
BT_HCI_UART_TX(A4)
GPS_RX
Conversion
BT_HCI_UART_RX(B5)
GPS PA EN(G3)
OSCILLATOR
RTC_CLK(H9)
32.768kHz
Bluetooth
Anttena
Sheet metal
IC702
Level
MPU/DSP