Transcript
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Power Suppply and UART Circuit D
D
Power Management Circuit
Customer's MCU
TXD_MCU
SI2333DS
R106 47K
R101
D101
24K
Q102
TIMER
RB520S30T1G
VCC_MODULE_3.3V
C
1K
TXD
Q101
VCC_MCU_3.3V
R105
RXD_MCU
C102
MCU
RXD
100nF
GPS_EN
GND
C
l e t l c a i e t u n Q fide n o C
GPIO_X
D103
VCC
GPIO_RESET
C101
VCC_MCU_3.3V
GPIO_X
4.7uF
U101
DTC143ZEBTL
D102
GPS_EN
RB520S30T1G
UART Circuit R102
TIMER: An open drain output signal can be used to control L80's main power
RXD1_MODULE
TXD_MCU
100R R103
RXD_MCU
100R
B
on/off. Please Note that when TIMER function is used in L80 module, ensure
that V_BAKP is constantly supplied with power.
TXD1_MODULE
B
For more details about TIMER, please refer to L80 Hardware Design.
R102,R103 are resrved for debugging the waveform of UART, and they can prevent L80 module from ESD interference. In general, 100R for R102 and R103 is recommended, but 0R also works well.
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Module Interface
D
Module Interface U301 TIMER
RESET EX_ANT
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TIMER 1PPS NC V_BCKP NC VCC GND RESET EX_ANT TXD1 GND RXD1
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Charging Circuit for RTC Domain
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VCC_MODULE_3.3V TXD1_MODULE RXD1_MODULE
C
C301
C302
10uF
100nF
VCC_MCU_3.3V
Test Points
VCC_MODULE_3.3V
1PPS V_BCKP
L80
D
TXD1
TXD1_MODULE
RXD1
RXD1_MODULE
VCC
VCC_MODULE_3.3V
GND
GND
D302 RB520S30T1G Schottky Diode R302 1K
V_BCKP
1. UART can be used to output NMEA message as well as to upgrade firmware.
B301
XH414
C303
4.7uF
C304
100nF
C
The V_BCKP pin can be directly supplied power by an external
2. The test points are reserved for debugging the GPS module.
rechargeable battery. Furthermore, it is necessary to add an external charging circuit for rechargeable battery.
Reset Circuit
Indicating Circuit
RESET
VCC_MODULE_3.3V
B
B
D301
1PPS
Q302
GPIO_RESET
R301 1K
DTC143ZEBTL
Q301
1. If the reset function is unused,the RESET pin can be connected
DTC143ZEBTL
to the VCC directly.
The 1PPS indicator will blink at 1Hz frequency after fixing the position.
2. RESET has been pulled up internally.
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Antenna Interface D
D
Inner Patch Antenna
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1. Keep at least 10mm distance to the nearest edge of the mother board. It will be better for L80 to be placed in the center of the mother board.
The minimum distance between antenna and enclosure is 1mm.
2. Keep enough distance between L80 antenna and tall components (h>6mm) and the minimum d is 10mm.
5. It is recommended that the mother board is bigger than 80mm×40mm for the better performance, and pour ground copper on the whole mother board
3. Put L80 on the top of the device, which can guarantee antenna to face to open sky and
C
4. Device enclosure should be made of non-metal materials especially around antenna area.
achieve good receiving performance during operation.
C
6. Other antennas such as BT/WIFI/GSM should be kept minimum 10mm distance far away from the embedded patch antenna in L80.
For more details, please refer to L80 Hardware Design.
EXT Active Antenna
By default, C401 and C402 are not mounted, R401 is 0R.
1. Pi circuit (C401,R401,C402) is reserved for impedance matching for antenna.
J401
2. R401 must not be a capacitance, because DC will flow from the R401 to the antenna.
B
R401
kept as short as possible.
0R C402 NM
C401 NM
B
3. Impedance of RF trace should be controlled by 50 ohm and the length should be
EX_ANT
Active Antenna
For more details, please refer to L80 Hardware Design.
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