Quectel L76 Guide

L76 Series
Reference Design
GNSS Module Series
Rev. B
Date: 2016-05-17
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GNSS Module Series
L76 Series Reference Design
L76_Series_Reference_Design Confidential / Released 1 / 4
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About the Document
History
Revision
Date
Author
Description
A
2016-04-26
Storm BAO
Initial
B
2016-05-17
Storm BAO
Added I2C information of L76-L
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L76 Series Reference Design
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Contents
About the Document...................................................................................................................................2
Contents.......................................................................................................................................................3
1Introduction..........................................................................................................................................4
1.1. Introduction................................................................................................................................4
1.2. Schematics................................................................................................................................4
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L76 Series Reference Design
L76_Series_Reference_Design Confidential / Released 4 / 4
1Introduction
1.1. Introduction
This document is a reference design for L76 series module. The schematics included in this document
are preliminary and are subject to change without prior notice.
1.2. Schematics
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Reference DesignL76 Series
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A2
UART Circuit
Power Management Circuit (Optional)
3.3V Power Suppply and UART Circuit
Customer's MCU
Generally, 100R for R102 and R103 is recommended, but 0R also works well.
R102, R103 are reserved for debugging the waveform of UART,
and they are also beneficial to ESD protection.
There are two ways to enter into backup mode and back to full on mode, you can choose
1. Send command “$PMTK225,4*2F” to enter into backup mode forever. The only way to
wake up the module is pulling the FORCE_ON high. Here, Q101, Q102, R101 are not
2. Cutting off VCC and keeping V_BCKP powered will make the module enter into backup
mode from full on mode. As long as the VCC pin is powered, the module will enter into full on
the dedicated way base on your requirement.
mounted; R104 and R106 are 0 ohm.
mode immediately. Here, Q101, Q102, R101 are mounted; R104 and R106 are not mounted.
C102
100nF
R105
1K
D101
C101
4.7uF
Q101
SI2333DS
R101
10K
Q102
DTC143ZEBTL
R104
NM_0R
VCC
GND
GPIO_X
RXD
GPIO_X
TXD
GPIO_X
U101
MCU
R102
100R
R103
100R
R106
NM_OR
VCC_MCU_3.3V GPS_EN
TXD_MCU
RXD_MCU
GPIO_RESET
GPIO_STANDBY
TXD_MCU RXD1_MODULE
RXD_MCU TXD1_MODULE
GPS_EN
VCC_MODULE_3.3V
VCC_MCU_3.3V
FORCE_ON
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Reference DesignL76 Series
A2
LDO Circuit
Customer's MCU
The transistor circuit will realize the voltage level shifting between
current from one power-on device to another power-off device.
Level Shifting for UART
5V Power Suppply and UART Circuit
VCC_MCU_5V and VCC_MODULE_3.3V, and block the leakage
1VIN
2GND
3CE
5
VOUT
4
NC
U202
XC6209F332MR
+
C201
100uF
C204
100nF
C202
100nF
R204
4.7K
R203
4.7K
Q202
R205
4.7K
Q201
R202
4.7K
R207
1K
D201
C203
4.7uF
R201
4.7K
R206
10K
VCC
GND
GPIO_X
RXD
GPIO_X
TXD
GPIO_X
U201
MCU
VCC_MCU_5V
TXD_MCU
RXD_MCU
VCC_MCU_5V
RXD_MCU
VCC_MCU_5V
VCC_MODULE_3.3V
TXD1_MODULE
VCC_MODULE_3.3V
RXD1_MODULE
TXD_MCU
VCC_MCU_5V
GPIO_RESET
GPIO_STANDBY
GPS_EN
VCC_MODULE_3.3V
GPS_EN
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Reference DesignL76 Series
A2
V_BCKP is designed to supply power for L76 series RTC
Indicating Circuit
Module Interface
The 1PPS indicator will blink at 1Hz frequency
Module Interface
Test Points
Charge Circuit for RTC Logic
logic circuit when VCC_MODULE_3.3V is powered off.
after fixing the position.
Reset Circuit
1. If the reset function is unused, the RESET
pin can be connected to the VCC directly.
Standby Circuit
2. Enter into standby mode: change the STANDBY pin
from high to low level.
3. Exit from standby mode: change the STANDBY pin
from low to high level.
For more details, please refer to L76 Series Hardware Design.
Schottky Diode
2. RESET has been pulled up internally.
1. STANDBY has been pulled up internally.
3. The test points are reserved for debugging the GNSS module.
2. For L76-L, pin16 and pin17 are I2C_SDA and I2C_SCL, respectively .
1. UART1 can be used to output NMEA message as well as to upgrade firmware.
For L76/L76B, pin16 and 17 are reserved,and please keep them open.
I2C Circuit for L76-L
1. I2C_SDA/I2C_SCL is pulled up to 2.8V inside L76-L moule.
There is no need to add a pull-up resistor externally.
2. The voltage threshold of I2C is 2.8V. If the system voltage
is not consistent with it,a level shifter circuit must be used.
B301 MS621FE-FL11E
R302
1K
D302
RB520S30T1G
Q301
DTC143ZEBTL
R301
1K
D301
L76_SERIES_RXD1
L76_SERIES_TXD1
GND
L76_SERIES_VCC
10 GND
11 RF_IN
12 GND
13 ANTON
14 VCC_RF
15 NC
16 RESERVED/I2C_SDA
17 RESERVED/I2C_SCL
18 FORCE_ON
9
RESET
8
VCC
7
NC
6
V_BCKP
5
STANDBY
4
1PPS
3
RXD1
2
TXD1
1
GND
U301
C302
100nF
Q302
DTC143ZEBTL
Q303
DTC143ZEBTL
C301
10uF
C303 4.7uF
C304 100nF
1VCC
2SDA
3SCL
4GND
U302
VCC_MODULE_3.3V
1PPS
TXD1_MODULE
RXD1_MODULE
VCC_MODULE_3.3V
GND
RF_IN
VCC_RF
VCC_MODULE_3.3V
RESET
GPIO_RESET
STANDBY
GPIO_STANDBY
VCC_MODULE_3.3V
V_BCKP
ANTON
RESET
VCC_MODULE_3.3V
V_BCKP
STANDBY
1PPS
TXD1_MODULE
RXD1_MODULE
FORCE_ON
I2C_SDA
I2C_SCL
I2C_SDA
I2C_SCL
VCC_MCU
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Reference DesignL76 Series
A2
Antenna Interface
1. Pi circuit (C401, C402, C403) is reserved for impedance matching for antenna.
For more details, please refer to L76 Series Hardware Design.
5. Impedance of RF trace should be controlled as 50 ohm and the trace length
should be kept as short as possible.
2. VCC_RF can be used as power supply for active antenna. Its typical value is 3.3V,
and the voltage ranges from 2.8V to 4.3V (VCC_RF=VCC). If it does not meet the
By default, C402 and C403 are not mounted; C401 is 100pF.
1.There is no need to use an external LNA for L76-L module
because an embedded LNA is already used inside the module.
Active Antenna
Passive Antenna
requirement of the active antenna, an external LDO could be used.
3. The voltage level of ANTON will be pulled down in standby mode.
4. If the L76 series module never enter into standby mode in the design, the ANTON
pin should be kept floated.
Optional:used to save
power if necessary.
(Optional)
LNA Circuit
2. Pi circuit (R405, C405, C406) is reserved for impedance matching for antenna.
By default, C405 and C406 are not mounted; R405 is 0R.
3. If an external LNA is added between passive antenna and L76/76B module, the total
sensitivity will be improved by about 3dB, which is beneficial for improving TTFF.
4. One typical reference circuit with BGA524N6 is given in the left figure. Here,
By default, C407 is 1nF; L402 is 8.2nH; and L403 is not mounted.
For more details, please refer to L76 Series Hardware Design.
7. Impedance of RF trace should be controlled as 50 ohm and the trace length should be
kept as short as possible.
5. VCC_RF can be used as power supply for LNA. Its voltage range is from 2.8V to 4.3V,
and its typical value is 3.3V (VCC_RF=VCC)
6. ANTON is an optional pin which can be used to control the enable pin of an external
LNA. If “ANTON” function is not used, please connect the pin “LNA ENABLE”
to VCC to keep LNA always on.
C407, L402 and L403 form a reserved matching circuit for the LNA BGA524N6.
No need to add for L76-L
which has an embedded LNA
C401
100pF
J401
Active Antenna
C403
NM
C402
NM
R401
10R
L401
47nH R402
10K
Q401
SI2333
Q402
DTC143ZEBTL
R405
0R
J402
Passive Antenna C406
NM
C405
NM
C409
33nF
C408
100pF
L402
8.2nH
L403
NM
4GND
5AI
6PON
3
AO 2
VCC 1
GND
U401
BGA524N6
C407
1nF
R403
100R
R404
100R
VCC_RF
RF_IN
ANTON
VCC_RF
RF_IN
ANTON
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