Quectel L76 Supplement

L76&L76-L
Hardware Design
GNSS Module Series
Version: 3.2
Date: 2021-08-16
Status: Released

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While Quectel has made efforts to ensure that the functions and features under development are free
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Copyright
The information contained here is proprietary technical information of Quectel. Transmitting, reproducing,
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or registration of a utility model or design.
Copyright © Quectel Wireless Solutions Co., Ltd. 2021. All rights reserved.

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Safety Information
The following safety precautions must be observed during all phases of operation, such as usage, service,
or repair of any terminal or mobile incorporating the module. Manufacturers of the terminal should notify
users and operating personnel of the following safety information by incorporating these guidelines into all
product manuals. Otherwise, Quectel assumes no liability for customers’ failure to comply with these
precautions.
Ensure that the product may be used in the country and the required environment,
as well as that it conforms to the local safety and environmental regulations.
Keep away from explosive and flammable materials. The use of electronic
products in extreme power supply conditions and locations with potentially
explosive atmospheres may cause fire and explosion accidents.
The product must be powered by a stable voltage source, and the wiring shall
conform to security precautions and fire prevention regulations.
Proper ESD handling procedures must be followed throughout the mounting,
handling and operation of any devices and equipment that incorporate the module
to avoid ESD damages.

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About the Document
Revision History
Document Information
Title
L76&L76-L Hardware Design
Subtitle
GNSS Module Series
Document Type
Hardware Design
Document Status
Released
Version
Date
Description
-
2013-02-08
Creation of the document
1.0
2013-02-08
First official release
1.1
2013-03-21
1. Deleted PMTK 291 command.
2. Changed R3 to 100R in figure 17.
3. Updated chapter 2.4.
4. Changed typical voltage of V_BCKP to 3.3 V.
1.2
2014-05-10
1. Modified the input power at RF_IN.
2. Changed the tracking sensitivity to -165 dBm.
1.3
2014-06-11
1. Updated packaging information.
2.0
2014-08-28
1. Added related information of L76B module.
2. Added the description of power supply requirement.
2.1
2015-11-11
1. Added the description of 1PPS VS NMEA.
2. Added the information about L76G module.
3.0
2016-04-26
1. Deleted the information about L76G module.
2. Added the information about L76-L module.
3. 3. Added chapter 3.9: EPO Data Service
3.1
2016-05-18
Added the description of I2C about L76-L module.

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3.2
2021-08-16
1. Deleted the information about L76B;
2. Added the information about the L76-L(L) module;
3. Updated the name of PIN2 from TXD1 to TXD;
4. Updated the name of PIN3 from RXD1 to RXD;
5. Updated the name of PIN9 from RESET to RESET_N;
6. Updated the name of PIN14 from VCC_RF to VDD_RF;
7. Updated the name of PIN18 from WAKE_UP to WAKEUP;
8. Added chapters 1.5, 1.6, 3.1, 3.4, 3.5, 5.2.2, 5.3, 8.2, and 9;
9. Updated the maximum altitude and accuracy of 1 PPS signal value
(Table 2);
10. Added the GLP mode (Chapter 3.3.5);
11. Updated the reference design for I2C interface (Figure 12);
12. Updated the recommended reflow soldering thermal profile
(Chapter 8.3).

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Contents
Safety Information.......................................................................................................................................3
About the Document...................................................................................................................................4
Contents.......................................................................................................................................................6
Table Index...................................................................................................................................................8
Figure Index.................................................................................................................................................9
1Product Description...........................................................................................................................10
1.1. Overview..................................................................................................................................10
1.2. Features ..................................................................................................................................11
1.3. Performance............................................................................................................................12
1.4. Block Diagram.........................................................................................................................13
1.5. GNSS Constellations ..............................................................................................................14
1.5.1. GPS................................................................................................................................14
1.5.2. BeiDou............................................................................................................................14
1.5.3. GLONASS......................................................................................................................14
1.5.4. Galileo............................................................................................................................15
1.5.5. QZSS..............................................................................................................................15
1.6. Augmentation System.............................................................................................................15
1.6.1. SBAS..............................................................................................................................15
1.7. AGNSS....................................................................................................................................15
1.7.1. EASY™ ..........................................................................................................................15
1.7.2. EPO™ ............................................................................................................................16
1.8. LOCUS....................................................................................................................................16
1.9. Multi-tone AIC..........................................................................................................................16
2Pin Assignment..................................................................................................................................18
3Power Management...........................................................................................................................21
3.1. Power Unit...............................................................................................................................21
3.2. Power Supply..........................................................................................................................22
3.2.1. VCC................................................................................................................................22
3.2.2. V_BCKP.........................................................................................................................23
3.3. Power Mode............................................................................................................................24
3.3.1. Continuous Mode...........................................................................................................24
3.3.2. Standby Mode................................................................................................................24
3.3.3. Backup Mode .................................................................................................................25
3.3.4. Periodic Mode................................................................................................................26
3.3.5. GLP Mode......................................................................................................................27
3.3.6. AlwaysLocate™ Mode ...................................................................................................28
3.4. Power-Up Sequence...............................................................................................................29
3.5. Power-Down Sequence ..........................................................................................................30
4Application Interfaces .......................................................................................................................31

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4.1. I/O Pins....................................................................................................................................31
4.1.1. Communication Interfaces.............................................................................................31
4.1.2. ANTON...........................................................................................................................33
4.1.3. 1PPS..............................................................................................................................33
4.1.4. System Pin.....................................................................................................................34
5Design .................................................................................................................................................36
5.1. Recommended Footprint.........................................................................................................36
5.2. Antenna Design.......................................................................................................................37
5.2.1. Antenna Specification ....................................................................................................37
5.2.2. Antenna Selection Guide...............................................................................................37
5.2.3. Active Antenna Reference Design.................................................................................38
5.2.4. Passive Antenna Reference Design..............................................................................40
5.3. Coexistence with Cellular Systems.........................................................................................41
5.3.1. In-Band Interference ......................................................................................................42
5.3.2. Out-of-Band Interference...............................................................................................43
5.3.3. Ensuring Interference Immunity.....................................................................................43
6Electrical Specification......................................................................................................................45
6.1. Absolute Maximum Ratings ....................................................................................................45
6.2. Recommended Operating Conditions.....................................................................................46
6.3. ESD Protection........................................................................................................................47
7Mechanical Dimensions....................................................................................................................48
7.1. Top, Side and Bottom View Dimensions ................................................................................48
7.2. Top and Bottom Views............................................................................................................49
8Product Handling...............................................................................................................................50
8.1. Packaging................................................................................................................................50
8.1.1. Tapes .............................................................................................................................50
8.1.2. Reels..............................................................................................................................51
8.2. Storage....................................................................................................................................51
8.3. Manufacturing and Soldering..................................................................................................52
9Labelling Information ........................................................................................................................55
10 Appendix References........................................................................................................................56

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Table Index
Table 1: Product Features.......................................................................................................................... 11
Table 2: Product Performance................................................................................................................... 12
Table 3: I/O Parameter Definition ..............................................................................................................18
Table 4: Pinout...........................................................................................................................................19
Table 5: Recommended Antenna Specifications....................................................................................... 37
Table 6: Intermodulation Distortion (IMD) Products...................................................................................43
Table 7: Absolute Maximum Ratings......................................................................................................... 45
Table 8: Recommended Operating Conditions..........................................................................................46
Table 9: Reel Packaging............................................................................................................................ 51
Table 10: Recommended Thermal Profile Parameters.............................................................................53
Table 11: Related Documents....................................................................................................................56
Table 12: Terms and Abbreviations........................................................................................................... 56

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Figure Index
Figure 1: Block Diagram............................................................................................................................. 14
Figure 2: Pin Assignment........................................................................................................................... 18
Figure 3: Internal Power Supply................................................................................................................. 22
Figure 4: VCC Input Reference Circuit ......................................................................................................23
Figure 5: RTC Powered by Non-rechargeable Battery.............................................................................. 23
Figure 6: Reference Charging Circuit for a Rechargeable Battery............................................................ 24
Figure 7: Enter/Exit from Backup Mode Sequence ................................................................................... 26
Figure 8: Periodic Mode............................................................................................................................. 27
Figure 9: AlwaysLocate™ Mode ................................................................................................................28
Figure 10: Power-Up Sequence.................................................................................................................29
Figure 11: Power-Down Sequence............................................................................................................ 30
Figure 12: UART Interface Reference Design...........................................................................................31
Figure 13: RS-232 Level Shift Circuit.........................................................................................................32
Figure 14: I2C Interface Reference Design for L76-L Module................................................................... 33
Figure 15: 1PPS & NMEA Timing.............................................................................................................. 34
Figure 16: Reference OC Circuit for Module Reset...................................................................................34
Figure 17: Reset Sequence .......................................................................................................................35
Figure 18: Recommended Footprint.......................................................................................................... 36
Figure 19: Active Antenna Reference Design without ANTON.................................................................38
Figure 20: Reference Design for Active Antenna with ANTON.................................................................39
Figure 21: Passive Antenna Reference Design without Additional LNA................................................... 40
Figure 22: Reference Design for Passive Antenna with Additional LNA...................................................41
Figure 23: In-Band Interference on GPS L1.............................................................................................. 42
Figure 24: Out-of-Band Interference on GPS L1....................................................................................... 43
Figure 25: Interference Source and Its Path..............................................................................................44
Figure 26: Top, Side and Bottom View Dimensions.................................................................................. 48
Figure 27: Top and Bottom Views..............................................................................................................49
Figure 28: Tape and Reel Specifications...................................................................................................50
Figure 29: Recommended Reflow Soldering Thermal Profile ...................................................................53
Figure 30: Labelling Information ................................................................................................................55

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1Product Description
1.1. Overview
The document contains L76, L76-L, L76-L(L) modules. You can choose the dedicated module based on
your requirement.
The modules support multiple global positioning and navigation systems: BeiDou, GPS, Galileo,
GLONASS and QZSS. These modules also support SBAS (including WAAS, EGNOS, MSAS and
GAGAN) and AGNSS functions. The default constellation configuration is GPS + GLONASS.
Key features:
⚫All the modules are single-band, multi-constellation GNSS devices and feature high-performance
and high reliability positioning engines. The modules facilitate a fast and precise GNSS positioning
capability.
⚫All the modules support serial UART communication interfaces. I2C is only supported by L76-L
module.
⚫Embedded with many advanced power saving modes including GLP, AlwaysLocate™, Standby and
Backup, the modules feature low-power consumption in different scenes.
⚫All the modules are featured with EASY™technology, one kind of AGNSS. Capable of collecting and
processing all internal aiding information like GPS time, ephemeris, last position, etc., the modules
deliver a very short Time to First Fix (TTFF) in either hot or warm start.
⚫The embedded flash memory provides the capacity for storing user-specific configurations and future
firmware updates.
⚫L76 and L76-L, the standard I/O voltage variants, have 2.7–2.9 V I/O voltage; L76-L(L), the low I/O
voltage variant has a 1.7–1.9 V I/O voltage.
⚫The three module variants are of a SMD form factor measuring 10.1 mm x 9.7 mm x 2.5 mm and can
be embedded in your application using the 18 LCC pins.
⚫The three modules are EU ROHS Directive compliant.

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1.2. Features
Table 1: Product Features
1
The I2C interface is supported only on certain firmware versions.
Features
L76
L76-L
L76-L(L)
Grade
Industrial



Automotive
-
-
-
Category
Standard Precision GNSS



High Precision GNSS
-
-
-
DR
-
-
-
RTK
-
-
-
Timing
-
-
-
Supply
2.8-4.3 V, Typical: 3.3 V



I/O
Typical: 2.8 V


-
Typical: 1.8 V
-
-

Communication
Interfaces
UART



SPI
-
-
-
I2C 1
-

-
Features
Additional LNA
-


Additional SAW



RTC crystal



TCXO oscillator



6-axis IMU
-
-
-
Constellations
GPS/QZSS
L1 C/A



L5
-
-
-

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For more information about GNSS constellation configuration, see document [1].
1.3. Performance
Table 2: Product Performance
2
Room temperature, all satellites at -130 dBm.
Galileo
E1



E5a
-
-
-
BeiDou
B1I



B2a
-
-
-
GLONASS
L1



IRNSS
L5
-
-
-
SBAS
L1



Temperature
Range
Operating temperature range: -40 °C to +85 °C
Storage temperature range: -40 °C to +90 °C
Physical
Characteristics
Size: (10.1 ±0.15) mm ×(9.7 ±0.15) mm ×(2.5 ±0.20) mm
Weight: Approx. 0.6 g
Parameter
Specification
L76
L76-L
L76-L(L)
Power Consumption 2
Acquisition
25 mA
31 mA
31 mA
Tracking
15 mA
31 mA
31 mA
Standby mode
0.5 mA
0.5 mA
0.5 mA
Backup mode
7 μA
8 μA
8 μA
Sensitivity
Acquisition
-148 dBm
-149 dBm
-149 dBm
Reacquisition
-160 dBm
-161 dBm
-161 dBm
NOTE

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1.4. Block Diagram
The following figure shows a block diagram of the modules. The modules include a GNSS IC, an
additional LNA (only supported by L76-L and L76-L(L)), an additional SAW filter, a TCXO and a XTAL.
The LNA is less susceptible to in-band interference in challenged environment (i.e. with a cellular module
transmitting B13 at the same time). This ensures enhanced performance in an environment where
jamming may be encountered.
3
Open-sky, active high precision GNSS antenna, less than 1 km baseline length.
4
CEP, 50%, 24 hours static, -130 dBm, more than 6 SVs.
Tracking
-165 dBm
-167 dBm
-167 dBm
TTFF2
(with AGNSS)
Cold Start
15 s
15 s
15 s
Warm Start
5 s
5 s
5 s
Hot Start
1 s
2 s
2 s
TTFF 3
(without AGNSS)
Cold Start
35 s
32 s
32 s
Warm Start
30 s
30 s
30 s
Hot Start
1 s
2 s
2 s
Horizontal Position Accuracy 4
2.5 m
Update Rate
1 Hz (max. 10 Hz)
Accuracy of 1PPS Signal
Typical accuracy: 100 ns
Time pulse width: 100 ms
Velocity Accuracy 2
Without aid: 0.1 m/s
Acceleration Accuracy2
Without aid: 0.1 m/s²
Dynamic Performance 2
Maximum Altitude: 10000 m
Maximum Velocity: 515 m/s
Acceleration: 4g

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Flash
RF F r on t -
E nd
In t e g r a t e d
L NA
Fractional-N
Syntheszer
GNSS
Engine
PMU
ARM7
Processor
Peripheral
controller
RTC
RAM
RF_IN
Active
Interference
Cancellation
32.768K XTAL
VCC
V_BCKP
I2C
RESET_N
STANDBY
1PPS
VDD_RF
ANTON
WAKEUP
Saw
filter
ROM
UART
(Only supported by L76-L )
LNA
(Only supported by
L76-L and L76-L(L)) TCXO
Figure 1: Block Diagram
1.5. GNSS Constellations
These modules are single-band GNSS receivers that can receive and track GPS, BeiDou, GLONASS,
Galileo, and QZSS signals.
1.5.1. GPS
These modules are designed to receive and track GPS L1 C/A (1574.397–1576.443 MHz) signals
provided by GPS.
1.5.2. BeiDou
They are designed to receive and track BeiDou B1I (1559.052–1563.144 MHz) signals provided by the
BeiDou Navigation Satellite System. The ability to receive and track BeiDou signals in conjunction with
GPS results in higher coverage, improved reliability, and better accuracy.
1.5.3. GLONASS
They are designed to receive and track GLONASS L1 signals (1597.781–1605.656 MHz) provided by
GLONASS.

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1.5.4. Galileo
They are designed to receive and track Galileo E1 (1573.374–1577.466 MHz) signals provided by
Galileo.
1.5.5. QZSS
The Quasi-Zenith Satellite System (QZSS) is a regional navigation satellite system that transmits
additional GPS L1 C/A signals for the Pacific region covering Japan and Australia. These modules can
detect and track these signals concurrently with GPS signals, resulting in better availability especially
under challenged conditions, e.g., in urban canyons.
1.6. Augmentation System
1.6.1. SBAS
The modules all support SBAS (Satellite-Based Augmentation System) broadcast signal reception, and
GPS data are complemented by additional regional or wide area GPS enhancement data. The system
enhances the data through satellite broadcasting, and the data can be used in GNSS receivers to
improve the accuracy of the results. SBAS satellites can also be used as additional signals for range or
distance measurement, further improving availability. Supported SBAS systems include WAAS, EGNOS,
MSAS and GAGAN.
1.7. AGNSS
The supported AGNSS feature significantly reduces the modules’TTFF, especially under lower signal
conditions. To implement AGNSS feature, the modules should get the assistance data including the
current time, rough position, and LTO data.
1.7.1. EASY™
The modules support the EASY™ feature to improve TTFF and improve the acquisition sensitivity. To
achieve that goal, the EASY™ feature provides assistant information, such as the ephemeris, almanac,
last rough position, time, and a satellite status.

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EASY™feature works as embedded software which can accelerate TTFF by predicting satellite
navigation messages from received ephemeris. The GNSS engine automatically calculates and predicts
orbit information for up to 3 days after first receiving the broadcast ephemeris, and saves the predicted
information into the internal memory. The GNSS engine will use the information for positioning if there is
not enough information from satellites. As a result, the function is helpful for positioning and TTFF
improvement.
The EASY™function can reduce TTFF to 5 s in warm start. In this case, RTC domain should be valid. In
order to gain enough broadcast ephemeris information from GNSS satellites, the GNSS module should
keep tracking the information for at least 5 minutes in good signal conditions after it fixes the position.
EASY™function is enabled by default. For more information about the corresponding command to
disable EASY™function, see document [1].
1.7.2. EPO™
The modules all feature a function called EPO™(Extended Prediction Orbit) which is a world leading
technology that supports 30-day orbit predictions to customers. Occasional download from the EPO
server is needed. For more information, see document [2].
1.8. LOCUS
These modules support the embedded logger function called LOCUS. This function can automatically log
position information to internal flash memory when enabled by dedicated LOCUS commands. With this
function, the host can save power consumption and does not need to track the NMEA information all the
time. LOCUS provides typically more log capacity without any added costs.
Software commands can be used to query the current state of LOCUS. For more information about these
commands, see document [1].
The raw data which MCU gets must be parsed via LOCUS parser code provided by Quectel. For more
details, please contact Quectel technical support.
1.9. Multi-tone AIC
The modules all support a function called Active Interference Cancellation (multi-tone AIC) to decease
harmonic distortion of GNSS signal induced by RF signal from Wi-Fi, Bluetooth, and the 2G and 3G
networks.

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Up to 12 multi-tone AIC embedded in each module can provide effective narrow-band interference and
jamming elimination. The GNSS signal could be demodulated from the jammed signal, which can ensure
better navigation quality. AIC function is enabled by default. For more information about the commands
that can be used to set AIC function, see document [1].

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2Pin Assignment
The modules are equipped with 18 LCC pins by which they can be mounted on the PCB.
TXD
GND
RXD
1PPS
STANDBY
V_BCKP
VCC
RESET_N
NC
RESERVED/
I2C_SCL
WAKEUP
RESERVED/
I2C_SDA
NC
VDD_RF
RF_IN
GND
ANTON
GND
9
1
2
3
4
5
6
7
8
10
18
17
16
15
14
13
12
11
L76&L76-L
&L76-L(L)
(Top View)
GND
POWER NC
IO ANTSYSTEM
Figure 2: Pin Assignment
Table 3: I/O Parameter Definition
Type
Description
AI
Analog Input
DI
Digital Input
DO
Digital Output
DIO
Digital Input/Output

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Table 4: Pinout
PI
Power Input
PO
Power Output
Function
Name
No.
I/O
Description
Remarks
Power
VCC
8
PI
Main power supply
Provides clean and steady
voltage.
Assure load current not less
than 150 mA.
V_BCKP
6
PI
Backup power supply for
RTC domain
Supplies power to the RTC
domain when VCC power
supply is disconnected.
IO
TXD
2
DO
Transmits data
UART port is used for NMEA
output, PMTK/PQ commands
input and firmware upgrade.
RXD
3
DI
Receives data
RESERVED/
I2C_SDA
16
DIO
For L76/L76-L(L) modules,
keep it open. For L76-L
module, this pin is
I2C_SDA.
For L76-L module, I2C Interface
outputs NMEA data by default
when reading; it can also
receive PMTK/PQ commands
through I2C bus.
RESERVED/
I2C_SCL
17
DIO
For L76/L76-L(L) modules,
keep it open. For L76-L
module, this pin is
I2C_SCL.
ANTON
13
DO
Control the ENABLE pin of
additional LNA and the
power supply of active
antenna.
If unused, leave the pin N/C (not
connected).
STANDBY
5
DI
Enter or exit from Standby
mode
The pin is pulled up internally. It
is edge-triggered.
If unused, leave the pin N/C (not
connected).
WAKEUP
18
DI
Wake up the modules from
Backup mode
Keep this pin open or pulled low
before entering Backup mode. It
belongs to RTC domain.
If unused, leave the pin N/C (not
connected).
1PPS
4
DO
One pulse per second
Synchronized on rising edge,
and the pulse width is 100 ms.
If unused, leave the pin N/C (not