L70
Quectel GPS Engine
Hardware Design
L70_HD_V1.0
L70 Hardware Design
Document Title
L70 Hardware Design
Revision
1.0
Date
2012-07-13
Status
Released
Document Control ID
L70_HD_V1.0
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General Notes
Quectel offers this information as a service to its customers, to support application and
engineering efforts that use the products designed by Quectel. The information provided is
based upon requirements specifically provided for customers of Quectel. Quectel has not
undertaken any independent search for additional information, relevant to any information
that may be in the customer’s possession. Furthermore, system validation of this product
designed by Quectel within a larger electronic system remains the responsibility of the
customer or the customer’s system integrator. All specifications supplied herein are subject to
change.
Copyright
This document contains proprietary technical information of Quectel Co., Ltd. Copying of
this document, distribution to others, and communication of the contents thereof, are
forbidden without permission. Offenders are liable to the payment of damages. All rights are
reserved in the event of a patent grant or registration of a utility model or design. All
specification supplied herein are subject to change without notice at any time.
Copyright © Quectel Wireless Solutions Co., Ltd. 2012
L70_HD_V1.0
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L70 Hardware Design
Contents
Contents ............................................................................................................................................ 2
Table Index........................................................................................................................................ 4
Figure Index ...................................................................................................................................... 5
0. Revision history ............................................................................................................................ 6
1. Introduction ................................................................................................................................... 7
1.1. Related documents .............................................................................................................. 7
1.2. Terms and abbreviations ...................................................................................................... 7
2. Product concept............................................................................................................................. 9
2.1. Key features ........................................................................................................................ 9
2.2. Block diagram ................................................................................................................... 10
2.3. Evaluation board ............................................................................................................... 11
2.4. New technology................................................................................................................. 11
2.4.1. EASY technology .................................................................................................... 11
2.4.2. AlwaysLocateTM mode ............................................................................................ 11
2.4.3. Multi-tone AIC ........................................................................................................ 12
2.5. Protocol ............................................................................................................................. 13
3. Application interface ................................................................................................................... 14
3.1. Pin assignment of the module ........................................................................................... 14
3.2. Pin description ................................................................................................................... 14
3.3. Operating modes ............................................................................................................... 16
3.4. Power supply ..................................................................................................................... 16
3.5. Turn on and Turn off ......................................................................................................... 17
3.5.1. Turn on .................................................................................................................... 17
3.5.2. Turn off.................................................................................................................... 17
3.5.3. Restart...................................................................................................................... 17
3.6. Power saving mode ........................................................................................................... 18
3.6.1. Standby mode .......................................................................................................... 18
3.6.2. Back up mode .......................................................................................................... 18
3.6.3. Periodic standby mode ............................................................................................ 20
3.6.4. AlwaysLocateTM standby mode ............................................................................... 21
3.7. UART interface ................................................................................................................. 21
3.8. ANTON ............................................................................................................................. 22
4. Antenna interface ........................................................................................................................ 24
4.1. Antenna ............................................................................................................................. 24
4.2. Antenna supply .................................................................................................................. 24
4.2.1. Passive antenna with external LNA......................................................................... 24
4.2.2. Active antenna without external LNA ..................................................................... 25
4.2.3. Active antenna with external LNA .......................................................................... 26
5. Electrical, reliability and radio characteristics ............................................................................ 27
5.1. Absolute maximum ratings................................................................................................ 27
5.2. Operating conditions ......................................................................................................... 27
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L70_HD_V1.0
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L70 Hardware Design
5.3. Current consumption ......................................................................................................... 28
5.4. Electro-static discharge ..................................................................................................... 28
5.5. Reliability test ................................................................................................................... 29
6. Mechanics ................................................................................................................................... 30
6.1. Mechanical view of the module ........................................................................................ 30
6.2. L70 Bottom dimension and recommended footprint......................................................... 30
6.3. Top view of the module .................................................................................................... 31
6.4. Bottom view of the module ............................................................................................... 32
7. Manufacturing ............................................................................................................................. 33
7.1. Assembly and soldering .................................................................................................... 33
7.2. Moisture sensitivity ........................................................................................................... 33
7.3. ESD safe ............................................................................................................................ 34
7.4. Tape and reel ..................................................................................................................... 34
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L70_HD_V1.0
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L70 Hardware Design
Table Index
TABLE 1: RELATED DOCUMENTS ..................................................................................................... 7
TABLE 2: TERMS AND ABBREVIATIONS ......................................................................................... 7
TABLE 3: MODULE KEY FEATURES .................................................................................................. 9
TABLE 4: THE PROTOCOL SUPPORTED BY THE MODULE ........................................................ 13
TABLE 5: PIN DESCRIPTION ............................................................................................................. 14
TABLE 6: OVERVIEW OF OPERATING MODES.............................................................................. 16
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TABLE 7: THE WAYS OF ENTERING AND EXITING FROM STANDBY MODE ......................... 18
TABLE 8: PIN DEFINITION OF THE V_BCKP PIN .......................................................................... 19
TABLE 9: PIN DEFINITION OF THE UART INTERFACES.............................................................. 21
TABLE 10: PIN DEFINITION OF THE ANTON ................................................................................. 23
TABLE 11: ANTENNA SPECIFICATION FOR L70 MODULE .......................................................... 24
TABLE 12: ABSOLUTE MAXIMUM RATINGS................................................................................. 27
TABLE 13: THE MODULE POWER SUPPLY RATINGS ................................................................... 27
TABLE 14: THE MODULE CURRENT CONSUMPTION (PASSIVE ANTENNA) .......................... 28
TABLE 15: THE ESD ENDURANCE TABLE (TEMPERATURE: 25℃, HUMIDITY: 45 %) ........... 28
TABLE 16: RELIABILITY TEST ......................................................................................................... 29
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L70 Hardware Design
Figure Index
FIGURE 1: MODULE BLOCK DIAGRAM ......................................................................................... 10
FIGURE 2: ALWAYSLOCATETM MODE ............................................................................................. 12
FIGURE 3: REFERENCE RESET CIRCUIT USING OC CIRCUIT ................................................... 17
FIGURE 4: REFERENCE RESET CIRCUIT USING BUTTON .......................................................... 17
FIGURE 5: TIMING OF RESTARTING SYSTEM .............................................................................. 18
FIGURE 6: RTC SUPPLY FROM NON-CHARGEABLE BATTERY OR CAPACITOR .................... 19
FIGURE 7: REFERENCE CHARGING CIRCUIT FOR CHARGEABLE BATTERY ........................ 19
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FIGURE 8: SEIKO XH414H-IV01E CHARGE CHARACTERISTIC ................................................. 20
FIGURE 9: PERIODIC MODE ............................................................................................................. 20
FIGURE 10: CONNECTION OF SERIAL INTERFACES ................................................................... 21
FIGURE 11: RS-232 LEVEL SHIFT CIRCUIT .................................................................................... 22
FIGURE 12: ANTON CONTROL CIRCUIT ........................................................................................ 23
FIGURE 13: TIMING OF EXTINT0 AND ANTON ............................................................................. 23
FIGURE 14: REFERENCE DESIGN FOR PASSIVE ANTENNA WITH LNA................................... 25
FIGURE 15: REFERENCE DESIGN FOR ACTIVE ANTENNA WITHOUT LNA ............................ 26
FIGURE 16: REFERENCE DESIGN FOR ACTIVE ANTENNA WITH LNA .................................... 26
FIGURE 17: L70 TOP VIEW AND SIDE VIEW(UNIT:MM) ......................................................... 30
FIGURE 18: L70 BOTTOM DIMENSION(UNIT:MM) .................................................................. 30
FIGURE 19: FOOTPRINT OF RECOMMENDATION(UNIT:MM)............................................... 31
FIGURE 20: TOP VIEW OF THE MODULE ....................................................................................... 31
FIGURE 21: BOTTOM VIEW OF THE MODULE .............................................................................. 32
FIGURE 22: RAMP-SOAK-SPIKE-REFLOW OF FURNACE TEMPERATURE .............................. 33
FIGURE 23: TAPE AND REEL SPECIFICATION ............................................................................... 34
L70_HD_V1.0
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L70 Hardware Design
0. Revision history
Revision
Date
Author
Description of change
1.0
2012-07-10
King HAO
Initial
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L70_HD_V1.0
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L70 Hardware Design
1. Introduction
This document defines and specifies L70 GPS module. It describes L70 hardware interface and its
external application reference circuits, mechanical size and air interface.
This document can help customer quickly understand the interface specifications, electrical and
mechanical details of L70 module. With the help of this document and other related documents,
customer can use L70 module to design and set up applications easily.
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1.1. Related documents
Table 1: Related documents
SN
[1]
[2]
[3]
Document name
Remark
L70_EVB _UGD
L70 EVB User Guide
L70_GPS_Protocol
L70 GPS Protocol Specification
L70_Reference_Design
L70 Reference Design
1.2. Terms and abbreviations
Table 2: Terms and abbreviations
Abbreviation
Description
AGPS
Assisted GPS
AIC
Active Interference Cancellation
CEP
Circular Error Probable
DGPS
Differential GPS
EASY
Embedded Assist System
EGNOS
European Geostationary Navigation Overlay Service
EMC
Electromagnetic Compatibility
EPO
ESD
GPS
Extended Prediction Orbit
Electrostatic Discharge
Global Positioning System
GNSS
Global Navigation Satellite System
GGA
GPS Fix Data
GLL
Geographic Position – Latitude/Longitude
GSA
GNSS DOP and Active Satellites
GSV
GNSS Satellites in View
HDOP
Horizontal Dilution of Precision
IC
Integrated Circuit
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L70 Hardware Design
I/O
Input /Output
Kbps
Kilo Bits Per Second
LNA
Low Noise Amplifier
MSAS
Multi-Functional Satellite Augmentation System
NMEA
National Marine Electronics Association
PDOP
Position Dilution of Precision
PMTK
MTK Proprietary Protocol
PPS
Pulse Per Second
PRN
Pseudo Random Noise Code
QZSS
Quasi-Zenith Satellite System
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RHCP
Right Hand Circular Polarization
RMC
Recommended Minimum Specific GNSS Data
RTCM
Radio Technical Commission for Maritime Services
SBAS
Satellite-based Augmentation System
SAW
Surface Acoustic Wave
TTFF
Time To First Fix
UART
Universal Asynchronous Receiver & Transmitter
VDOP
Vertical Dilution of Precision
VTG
Course over Ground and Ground Speed, Horizontal Course and Horizontal
Velocity
WAAS
Wide Area Augmentation System
Inom
Nominal Current
Imax
Maximum Load Current
Vmax
Maximum Voltage Value
Vnom
Nominal Voltage Value
Vmin
Minimum Voltage Value
VIHmax
Maximum Input High Level Voltage Value
VIHmin
Minimum Input High Level Voltage Value
VILmax
Maximum Input Low Level Voltage Value
VILmin
Minimum Input Low Level Voltage Value
VImax
Absolute Maximum Input Voltage Value
VImin
Absolute Minimum Input Voltage Value
VOHmax
Maximum Output High Level Voltage Value
VOHmin
Minimum Output High Level Voltage Value
VOLmax
Maximum Output Low Level Voltage Value
VOLmin
Minimum Output Low Level Voltage Value
L70_HD_V1.0
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L70 Hardware Design
2. Product concept
The L70 GPS module brings the high performance of the MTK positioning engine to the industrial
applications. It is able to achieve the industry’s highest level of sensitivity, accuracy and TTFF with
the lowest power consumption in a small-footprint lead-free package. With 66 search channels and 22
simultaneous tracking channels, it acquires and tracks satellites in the shortest time even at indoor
signal level. The embedded flash memory provides capacity for storing user-specific configurations
and allows for future updates.
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The L70 module combines with many advanced features including AlwaysLocateTM , EASYTM, and
AIC. These features are beneficial to reduce consumption and accelerate TTFF for L70 module.
The module supports various location, navigation and industrial applications including autonomous
GPS, SBAS (including WAAS, EGNOS, MSAS, and GAGAN), QZSS, and AGPS.
The L70 is an SMD type module with the compact 10.1mm x 9.7mm x 2.5mm form factor, which can
be embedded in customer applications through the 18-pin pads. It provides necessary hardware
interfaces between the module and customer’s board.
The module is fully RoHS compliant to EU regulation.
2.1. Key features
Table 3: Module key features
Feature
Implementation
Power supply
Power consumption (passive
antenna)
Single supply voltage: 2.8V~4.3V



Acquisition
Tracking
Standby
Receiver Type


GPS L1 1575.42MHz C/A Code
66 search channels, 22 simultaneous tracking channels
Sensitivity




Cold Start
Reacquisition
Hot start
Tracking
-145dBm
-157 dBm
-157 dBm
-160 dBm
Sensitivity
(with external LNA)




Cold Start
Reacquisition
Hot Start
Tracking
-148 dBm
-160 dBm
-160 dBm
-163 dBm
Time-To-First-Fix(EASY
enabled)



Cold Start
Warm Start
Hot Start
15s average@-130dBm
5s average@-130dBm
1s @-130dBm
L70_HD_V1.0
typical : 3.3V
25mA@-130dBm
22mA@-130dBm
0.5mA@VCC=3.3V
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L70 Hardware Design


Cold Start (Autonomous)
35s average@-130dBm
Warm Start (Autonomous)
30s average@-130dBm

Hot Start (Autonomous)
1s@-130dBm
Horizontal Position
Accuracy(@-130dBm)

<2.5 m CEP
Max Update Rate

Up to 10Hz,1Hz by default
Accuracy of 1PPS Signal

Typical accuracy <15ns (Not support time service)

Time pulse width 100ms
Velocity Accuracy

Without Aid
0.1 m/s
Acceleration Accuracy

Without Aid
0.1 m/s²
Time-To-First-Fix(EASY
disabled)
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Dynamic Performance
UART Port

Maximum Altitude

Maximum Velocity
515 m/s Maximum

Acceleration
4G


UART Port: TXD1 and RXD1
Supports baud rate from 4800bps to 115200bps,9600bps with
default
UART Port is used for NMEA output, MTK proprietary
messages input and firmware upgrade

18,000 m
Temperature range


Physical Characteristics
Size: 10.1±0.15 x 9.7±0.15 x 2.5±0.15mm
Weight: Approx. 0.6g
Normal operation: -40°C ~ +85°C
Storage temperature: -45°C ~ +125°C
2.2. Block diagram
The following figure shows a block diagram of L70 module. It consists of a single chip GPS IC which
includes RF part and Baseband part, a SAW filter, a TCXO and a crystal oscillator.
RF_IN
Saw
filter
RF Front-End
Integrated LNA
Fractional-N
Syntheszer
Active
Interference
Cancellation
Integrated
LDO
&PMU
VCC
VCC_RF
V_BCKP
GPS Engine
TCXO
UART
Peripheral
controller
ROM
RAM
ARM7
Processor
Serial
Flash
NRESET
EXTINT
1PPS
ANTON
RTC
32.768K XTAL
Figure 1: Module block diagram
L70_HD_V1.0
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L70 Hardware Design
2.3. Evaluation board
In order to help customers on the application of L70 module, Quectel supplies an Evaluation Board
(EVB) with appropriate power supply, RS-232 serial cable, active antenna and other peripherals to test
the module.
For more details, please refer to the document [1].
2.4. New technology
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2.4.1. EASY technology
By Supplying aided information like ephemeris, almanac, rough last position and time, and satellite
status,AGPS can help improve GPS receiver TTFF and the acquisition sensitivity. The L70 module
supports EASY technology which is one kind of AGPS.
EASY works as an embedded software which can accelerate TTFF by predicting satellite navigation
messages from received ephemeris. The GPS engine will calculate and predict orbit information
automatically up to 3 days after first receiving the broadcast ephemeris, and saving the predicted
information into the internal memory. GPS engine will use these information for positioning if no
enough information from satellites, so the function will be helpful for positioning and TTFF
improvement under indoor and urban condition.
The EASY function can reduce TTFF to 5s for warm start. In this case, the backup power which
supplies power for the RTC circuit is necessary. If no backup power, L70 module cannot store the
extended ephemeris information and predict orbit information, in other words, it will become the cold
start. Although the EASY also can accelerate TTFF in cold start, the backup power is still strongly
recommended.
In order to gain enough broadcast ephemeris information from GPS satellites, the GPS module should
receive the information for at least 5 minutes in the good signal condition after it turned on.
EASYTM function is enabled by default. The command “$PMTK869,0*29” can be used to query the
status of EASY. If EASY is enabled, the module returns “ $PMTK869,2,1*36”, else returns
“$PMTK869,2,0*37”.
2.4.2. AlwaysLocateTM mode
AlwaysLocateTM is an intelligent controller of L70 normal mode and sleep mode. It is one of the
power saving modes. According to the environmental and motion conditions, L70 can adaptively
adjust the on/off time to achieve the balance between positioning accuracy and power consumption.
L70_HD_V1.0
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L70 Hardware Design
The following picture has shown the rough relationship between power consumption and the different
scenarios in daily life when the AlwaysLocateTM mode is enabled.
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Figure 2: AlwaysLocateTM mode
The position accuracy in AlwaysLocateTMmode will be somewhat degraded, especially in high speed.
So this mode is not recommended in the applications of vehicle system.
AlwaysLocateTMmode is disabled by default. Using the MTK proprietary commands can enable the
AlwaysLocateTMmode. Please refer to the following commands to set the AlwaysLocateTM mode.
Enable AlwaysLocateTM mode: $PMTK225,8*23;Return: $PMTK001,225,3*33
Back to normal mode: $PMTK225,0*2B
2.4.3. Multi-tone AIC
Up to 12 multi-tone AIC (Active interference Cancellation) can provide effective narrow-band
interference and jamming elimination. The GPS signal could be recovered from the jammed signal,
which can ensure better navigation quality.
Because different applications (Wi-Fi, GSM/GPRS, 3G/4G, Bluetooth) are integrated into navigation
system, the harmonic of RF signal will influence the GPS reception. The multi-tone AIC can reject
external RF interference which comes from other active components on the main board, to improve
the capacity of GPS reception without any hardware change in the design.
AIC function is enabled by default. The following commands can be used to set AIC function.
Enable AIC function: $PMTK 286,1*23
Disable AIC function: $PMTK 286,0*22
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L70 Hardware Design
2.5. Protocol
The module supports standard NMEA-0813 protocol and MTK proprietary protocol (PMTK messages)
that can be used to provide extended capabilities for many applications. The module is capable of
supporting the following NMEA formats: GGA, GSA, GLL, GSV, RMC, VTG .
Table 4: The protocol supported by the module
Protocol
NMEA
PMTK
Type
Output, ASCII, 0183, 3.01
Input, MTK proprietary protocol
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Note: Please refer to document [2] about NMEA standard protocol and MTK proprietary protocol.
L70_HD_V1.0
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L70 Hardware Design
3. Application interface
The module is equipped with an 18-pin 1.1mm pitch SMT pad that connects to the user application
platform. Sub-interfaces included in these pads are described in details in the following chapters.
3.1. Pin assignment of the module
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VRESET
9
VCC
8
NC
7
V_BCKP
6
EXTINT0
5
TIMEPULSE
4
NC
RXD1
3
17
NC
TXD1
2
18
RESERVED
GND
1
10
GND
11
RF_IN
12
GND
13
ANTON
14
VCC_RF
15
RESERVED
16
L70
(Top View)
3.2. Pin description
Table 5: Pin description
Power Supply
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
VCC
8
I
Supply voltage
Vmax= 4.3V
Vmin=2.8V
Vnom=3.3V
Supply current of no less
than 150mA.
V_BCKP
6
I
Backup voltage
supply
Vmax=4.3V
Vmin=2.0V
Vnom=2.8V
IBCKP=7uA@Backup
mode
Power supply for RTC
domain when VCC does not
supply for the system.
VCC_RF
14
O
Output voltage RF
section
Vmax=4.3V
Vmin=2.8V
Vnom=3.3V
Imax=50mA
Usually supply for external
active antenna or LNA. If
unused, keep this pin open.
VVCC_RF≈ VVCC
Reset
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L70 Hardware Design
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
VRESET
9
I
System reset, low
level active.
VILmin=-0.3V
VILmax=0.8V
VIHmin=2.0V
VIHmax=3.6V
If unused, keep this pin
open or connect it to the
VCC.
General purpose input/output
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
EXTINT0
5
I
External interrupt
input
VILmin=-0.3V
VILmax=0.8V
VIHmin=2.0V
VIHmax= 3.6V
This pin can be used to
enter or exit from the
standby mode. If unused,
keep this pin open.
Internally pulled up.
O
Time pulse
VOLmin=-0.3V
VOLmax=0.4V
VOHmin=2.4V
VOHmax=3.1V
1 pulse per second (1PPS).
Synchronized at rising edge,
the pulse width is100ms. If
unused, keep this pin open.
COMMENT
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TIMEPULSE 4
UART port
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
RXD1
3
I
Receive data
VILmin=-0.3V
VILmax=0.8V
VIHmin=2.0V
VIHmax= 3.6V
2
O
Transmit data
VOLmin=-0.3V
VOLmax=0.4V
VOHmin=2.4V
VOHmax=3.1V
PIN NAME
PIN
NO.
I/O
DESCRIPTION
DC
CHARACTERISTICS
COMMENT
RF_IN
11
I
GPS signal input
Characteristic
impedance of 50Ω
Refer to chapter 4
13
O
Active antenna or
external LNA control
pin in power standby
mode
The typical value is
2.8V.
This pin can be used to
control the power supply of
the Active antenna or the
enable pin of the external
LNA in the standby mode.
If unused, keep this pin
open.
TXD1
RF interface
ANTON
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L70 Hardware Design
3.3. Operating modes
The table below briefly summarizes the various operating modes of L70 module.
Table 6: Overview of operating modes
Mode
Function
Acquisition mode
The module starts to search satellite, determine visible satellites and
coarse carrier frequency and code phase of satellite signals. When the
acquisition is completed, it switches to tracking mode automatically.
The module refines acquisition’s message, as well as keeps tracking
and demodulating the navigation data from the specific satellites.
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Tracking mode
Standby mode
Power
saving
mode
Using EXTINT0 pin or PMTK command can make the module enter
the standby mode. In this mode, the UART port is still accessible, but
has no NEMA messages output, the current consumption of the
module is also minimal.
Backup mode
When cutting off the main power supply, the module will enter the
backup mode. In this mode, the RTC (Real Time Clock) power
supply is needed. It can supply power for backed-up memory which
contains all the necessary GPS information for quick start-up and a
small amount of user configuration variables.
Periodic standby
mode
Periodic standby mode is a periodic mode that can control the on/off
time of L70 module periodically to reduce power consumption. It
supports the module to switch automatically between normal mode
and standby mode.
AlwaysLocateTM
standby mode
AlwaysLocateTM is an intelligent controller of L70 periodic mode.
AlwaysLocateTM standby mode supports the module to switch
automatically between normal mode and standby mode. According to
the environmental and motion conditions, the module can adaptively
adjust the on/off time to achieve the balance between positioning
accuracy and power consumption.
3.4. Power supply
The main power supply is fed through the VCC pin. It is important that the system power supply
circuitry is able to support the peak power. So the power supply must be able to provide sufficient
current up to 150mA.
The power supply of RTC circuit is fed through the V_BCKP pin. For more details, please refer to
chapter 3.6.2.
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L70 Hardware Design
3.5. Turn on and Turn off
3.5.1. Turn on
The module will be turned on when VCC is supplied.
3.5.2. Turn off
Shutting down the module's main power supply is the only way to turn off the module. In this case, if
the backup power is still present, the module will enter the backup mode.
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3.5.3. Restart
L70 module can be restarted by driving the VRESET to a low level voltage for a certain time and then
releasing it. An OC driver circuit as shown below is recommended to control the VRESET.
VRESET
4.7K
Input pulse
47K
Figure 3: Reference reset circuit using OC circuit
The other way to control the VRESET pin is using a button directly. A TVS component needs to be
placed close to the button for ESD protection. While pressing the key, ESD strike may generate from
finger. A reference circuit is illustrated in Figure 4.
S1
VRESET
TVS1
Close to S1
Figure 4: Reference reset circuit using button
L70_HD_V1.0
- 17 -
L70 Hardware Design
The restart timing has been illustrated in Figure 5.
VCC
<170ms
Pulldown
> 10ms
VIH >2.0V
VRESET
(INPUT)
VIL<0.8V
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Figure 5: Timing of restarting system
3.6. Power saving modes
3.6.1. Standby mode
Standby mode is one of the power saving modes, in this mode, the UART serial port is still accessible,
but has no NEMA messages output, the current consumption of the module is also minimal. The
following table has shown the ways how to enter and exit from the standby mode.
Table 7: The ways of entering and exiting from standby mode
Mode
Operation
Changing the level of EXTINT0 pin from high to low.
Enter the
standby mode
Sending the MTK proprietary command“$PMTK l61,0*28 ”.
Changing the level of EXTINT0 pin from low to high.
Exit from
standby mode
Sending any byte through the UART port.
Note: Recommended to pull EXTINT0 pin high before turning on the module.
3.6.2. Back up mode
When cutting off the main power supply, the module will enter the backup mode. In this mode, the
RTC (Real Time Clock) power supply is needed. It can supply power for backed-up memory which
contains all the necessary GPS information for quick start-up and a small amount of user configuration
variables. The RTC power supply of module can be directly provided by an external capacitor or
battery (rechargeable or non-chargeable) through the V_BCKP pin.
L70_HD_V1.0
- 18 -
L70 Hardware Design
Table 8: Pin definition of the V_BCKP pin
Name
Pin No.
Function
V_BCKP
6
Backup voltage supply
Note: The V_BCKP could not keep open. The V_BCKP pin should be connected to a battery or a
capacitor for GPS module warm/hot start and AGPS.
Please refer to the following figure for RTC backup:
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MODULE
V_BCKP
RTC
LDO
Non-chargeable
battery or capacitor
Figure 6: RTC supply from non-chargeable battery or capacitor
The V_BCKP pin does not implement charging for rechargeable battery. It is necessary to add a
charging circuit for rechargeable battery, shown as the following figure:
VCC
1K
Charge Circuit
MODULE
V_BCKP
RTC
LDO
Chargeable
Backup Battery
Figure 7: Reference charging circuit for chargeable battery
 Coin-type Capacitor backup
Coin-type Rechargeable Capacitor such as XH414H-IV01E from Seiko can be used.
L70_HD_V1.0
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L70 Hardware Design
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Figure 8: Seiko XH414H-IV01E charge characteristic
3.6.3. Periodic standby mode
Periodic standby mode is a periodic mode that can control the on/off time of L70 module periodically
to reduce power consumption. It supports the module switches automatically between normal mode
and standby mode. The following figure has shown the operation of periodic mode.
Figure 9: Periodic mode
Sending PMTK command can enter periodic standby mode. The ratio of run time and sleep time can
be set by the command. For more details, please refer to document [2] about the MTK proprietary
protocol.
L70_HD_V1.0
- 20 -
L70 Hardware Design
3.6.4. AlwaysLocateTM standby mode
AlwaysLocateTM is an intelligent controller of L70 normal mode and standby mode. AlwaysLocateTM
standby mode supports the module to switch automatically between normal mode and standby mode.
According to the environmental and motion conditions, the module can adaptively adjust the on/off
time to achieve the balance between positioning accuracy and power consumption.
For more details, please refer to chapter 2.4.2.
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3.7. UART interface
The module provides one universal asynchronous receiver & transmitter serial port. The module is
designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data
Terminal Equipment) connection. The module and the client (DTE) are connected through the
following signal shown as Figure 10. It supports data baud-rate from 4800bps to 115200bps.
UART port
 TXD1: Send data to the RXD signal line of DTE
 RXD1: Receive data from the TXD signal line of DTE
Table 9: Pin definition of the UART interfaces
Interface
UART Port
Name
Pin No.
Function
TXD1
2
Transmit data
RXD1
3
Receive data
MODULE (DCE)
Serial port
CUSTOMER (DTE)
TXD1
TXD
RXD1
RXD
GND
GND
Figure 10: Connection of serial interfaces
This UART port has the following features:
 UART port can be used for firmware upgrade, NMEA output and PMTK proprietary messages
L70_HD_V1.0
- 21 -
L70 Hardware Design


input.
The default output NMEA type setting is RMC, VTG, GGA, GSA, GSV, GLL.
UART port supports the following data rates:
4800, 9600, 14400, 19200, 38400, 57600, 115200.
The default setting is 9600bps, 8 bits, no parity bit, 1 stop bit .
Hardware flow control and synchronous operation are not supported.
The UART port does not support the RS-232 level but only supports the CMOS level. If the module’s
UART port is connected to the UART port of a computer, it is necessary to add a level shift circuit
between the module and the computer. Please refer to the following figure.
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28
25
1
3
TXD1
Module
3.3V
V+
C1-
GND
C2+
VCC
C2-
V-
24
23
22
19
T1IN
T2IN
T3IN
T4IN
17
T5IN
16
21
20
18
RXD1
C1+
13
/R1OUT
R1OUT
R2OUT
R3OUT
T4OUT
T2OUT
T3OUT
T1OUT
T5OUT
R1IN
R2IN
R3IN
27
2
26
3.3V
4
10
6
7
5
12
8
9
11
ONLINE
15
/STATUS
14
/SHUTDOWN
6
7
8
9
To PC serial port
1
2
3
4
5
GND
Figure 11: RS-232 level shift circuit
3.8. ANTON
The ANTON is an optional pin which can be used to control the power supply of active antenna or the
enable pin of the external LNA. The recommended circuit diagram is shown in Figure 12. When L70
module enters the standby mode, the ANTON pin will be pulled down, the Q1 and Q2 are in high
impedance state and the power supply for antenna is cut off. In normal mode, the voltage value of
ANTON is about 2.8V, it will make Q1 and Q2 in the on-state, then VCC_RF will provide power
supply for the active antenna. Figure 13 has shown the timing between the ANTON pin and the
EXTINT0 pin.
L70_HD_V1.0
- 22 -
L70 Hardware Design
Table 10: Pin definition of the ANTON
Name
Pin No.
Function
ANTON
13
Control the power supply of the active GPS antenna or the enable pin of
the external LNA.
Active Antenna
L70_Module
LNA
RF_IN
EN
VCC
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L1 47nH
R3 100R
R1 10R
ANTON
Q1
Q2
R2 10K
VCC_RF
Figure 12: ANTON control circuit
Figure 13: Timing of EXTINT0 and ANTON
L70_HD_V1.0
- 23 -
L70 Hardware Design
4. Antenna interface
The L70 module receives L1 band signal from GPS satellites at a nominal frequency of 1575.42MHz.
The RF signal is connected to the RF_IN pin. Customer should use a controlled impedance
transmission line of 50 Ohm to connect to RF_IN.
4.1. Antenna
L70 module can be connected to passive or active antenna.
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Table 11: Antenna specification for L70 module
Antenna type
Specification
Passive antenna
Center frequency:
Band Width:
Gain:
Polarization:
Active antenna
Center frequency:
Band Width:
Minimum gain:
Maximum noise figure:
Maximum gain:
Polarization:
1575.42 MHz
>20 MHz
>0 dBi
RHCP or Linear
1575.42 MHz
>5 MHz
15-20dB(compensate signal loss in RF cable)
1.5dB
50dB
RHCP or Linear
4.2. Antenna supply
4.2.1. Passive antenna with external LNA
Typically a design using a passive antenna requires more attention regarding the layout of the RF
section. An external LNA between the passive antenna and the L70 module is strongly recommended
to add for improving receiver sensitivity. It is always beneficial to reserve a П or L passive matching
network between the passive antenna and the LNA. Figure14 is the rough reference design. For more
details, please refer to document [3].
L70_HD_V1.0
- 24 -
L70 Hardware Design
Passive Antenna
BGA715L7
R1 0R
C1 NM
C2 NM
П matching circuit
R2
150R
RF_IN
EN
vcc
LNA
L70_Module
R3
100R
ANTON
VCC_RF
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Figure 14: Reference design for passive antenna with LNA
Note: VCC_RF is directly connected to the power supply of L70 module internally. If VCC_RF is
not suitable to the external LNA, using R2 as a divider or adding an external LDO circuit to get the
required voltage. R3 is used as a current limiting resistor.
4.2.2. Active antenna without external LNA
Active antenna could be connected to RF_IN directly and you also can reserve a П or L passive
matching network between the active antenna and the L70 module. If an active antenna is connected
to RF_IN, the integrated low-noise amplifier of the antenna must be powered by an external correct
supply voltage. Generally, the supply voltage is fed to the antenna through the coaxial RF cable. An
active antenna’s loading current is between 5mA to 20mA. The inductor L1 outside of the module
prevents the RF signal from leaking into the VCC_RF pin and routes the bias supply to the active
antenna. Please refer to the reference circuit shown in Figure 15.
If the VCC_RF voltage does not meet the requirements for powering the active antenna, an external
LDO could be used.
L70_HD_V1.0
- 25 -
L70 Hardware Design
Active Antenna
П matching circuit
L70_Module
C1 NM
C2 NM
R3 0R
RF_IN
10R
L1 47nH
R1
ANTON
R2
10K
Q1
Q2
VCC_RF
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Figure 15: Reference design for active antenna without LNA
Note: The rated power of resistor R1 should be chosen no less than 1 watt in case active antenna is
shorted unexpectedly. In order to reduce consumption, the value of resistor R2 is not recommended
to choose too small.
4.2.3. Active antenna with external LNA
In order to obtain better receiver sensitivity, an active antenna and an external LNA are recommended.
You also can reserve a П or L passive matching network between the active antenna and the LNA. The
rough reference circuit is shown in Figure16. For more details, please refer to document [3].
Active Antenna
П matching circuit
C1 NM
C2 NM
L70_Module
LNA
R3 0R
EN
VCC
RF_IN
R4
R5
L1
R1
Q1
Q2
R2
ANTON
VCC_RF
Figure 16: Reference design for active antenna with LNA
L70_HD_V1.0
- 26 -
L70 Hardware Design
5. Electrical, reliability and radio characteristics
5.1. Absolute maximum ratings
Absolute maximum rating for power supply and voltage on digital pins of the module are listed in
Table 12.
Table 12: Absolute maximum ratings
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Parameter
Min
Max
Unit
Power supply voltage (VCC)
-0.3
4.3
V
Backup battery voltage (V_BCKP)
-0.3
4.3
V
Input voltage at digital pins
-0.3
3.6
V
VCC_RF output current (Ivccrf)
50
mA
Input power at RF_IN (Prfin)
0
dBm
125
°C
-45
Storage temperature
Note: Stressing the device beyond the “Absolute Maximum Ratings” may cause permanent damage.
These are stress ratings only. The product is not protected against over voltage or reversed voltage.
If necessary, voltage spikes exceeding the power supply voltage specification, given in table above,
must be limited to values within the specified boundaries by using appropriate protection diodes.
5.2. Operating conditions
Table 13: The module power supply ratings
Parameter
Description
Conditions
Min
Typ
Max
Unit
VCC
Supply voltage
Voltage must stay
within the min/max
values, including
voltage drop, ripple,
and spikes.
2.8
3.3
4.3
V
IVCCP*
Peak supply current
VCC=3.3V
150
mA
V_BCKP
Backup voltage supply
4.3
V
VCC_RF
Output voltage RF
section
VCC
V
IVCC_RF
VCC_RF output
current
50
mA
TOPR
Normal Operating
temperature
85
℃
L70_HD_V1.0
2.0
-40
3.3
25
- 27 -
L70 Hardware Design
* This figure can be used to determine the maximum current capability of power supply.
Note: Operation beyond the "Operating Conditions" is not recommended and extended exposure
beyond the "Operating Conditions" may affect device reliability.
5.3. Current consumption
The values for current consumption are shown in Table 14.
Table 14: The module current consumption (passive antenna)
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Parameter
Condition
Min
Typ
Max
Unit
Icc @Acquisition
@-130dBm
25
mA
Icc @Tracking
@-130dBm(For Cold Start, 10
minutes after First Fix. For Hot
Start, 15 seconds after First
Fix.)
22
mA
Icc @Standby
@VCC=3.3V
0.5
mA
IBCKP @backup
@V_BCKP=3.3V
7
uA
Note: In the standby mode, the power supply to active antenna through VCC_RF is cut off. It will
be re-activated when the module exits from the standby mode.
5.4. Electro-static discharge
L70 module is an ESD sensitive device. ESD protection precautions should still be emphasized.
Proper ESD handing and packaging procedures must be applied throughout the processing, handing
and operation of any application.
The ESD bearing capability of the module is listed in Table 15. Note that the customer should add
ESD components to module pins in the particular application except RF_IN, VCC and GND pins.
Table 15: The ESD endurance table (Temperature: 25℃, Humidity: 45 %)
Pin
Contact discharge
Air discharge
VCC,GND
±5KV
±5KV
±10KV
±10KV
UART
±3KV
±6KV
Others
±2KV
±4KV
RF_IN
L70_HD_V1.0
- 28 -
L70 Hardware Design
5.5. Reliability test
Table 16: Reliability test
Test term
Condition
Standard
Thermal shock
-30°C...+80°C, 144 cycles
Damp heat, cyclic
+55°C; >90% Rh 6 cycles for 144 hours
Vibration shock
2
3
GB/T 2423.22-2002 Test
Na
IEC 68-2-14 Na
2
3
5~20Hz,0.96m /s ;20~500Hz,0.96m /s -3dB/oct,
IEC 68-2-30 Db Test
2423.13-1997 Test Fdb
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Heat test
1hour/axis; no function
IEC 68-2-36 Fdb Test
85°C, 2 hours, Operational
GB/T 2423.1-2001 Ab
IEC 68-2-1 Test
Cold test
-40°C, 2 hours, Operational
GB/T 2423.1-2001 Ab
IEC 68-2-1 Test
Heat soak
90°C, 72 hours, Non-Operational
GB/T 2423.2-2001 Bb
IEC 68-2-2 Test B
Cold soak
-45°C, 72 hours, Non-Operational
GB/T 2423.1-2001 A
IEC 68-2-1 Test
L70_HD_V1.0
- 29 -
L70 Hardware Design
6. Mechanics
This chapter describes the mechanical dimensions of the module.
6.1. Mechanical view of the module
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Figure 17: L70 Top view and Side view(Unit:mm)
6.2. L70 Bottom dimension and recommended footprint
Figure 18: L70 Bottom dimension(Unit:mm)
L70_HD_V1.0
- 30 -
L70 Hardware Design
Keep Out
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Figure 19: Footprint of recommendation(Unit:mm)
Notes:
1. The keep-out area should be covered by solder mask and top silk layer for isolation between the
top layer of host board and the bottom layer of the module.
2. For easy maintenance of this module and accessing to these pads, please keep a distance of no
less than 3mm between the module and other components in host board.
6.3. Top view of the module
1
18
9
10
Figure 20: Top view of the module
L70_HD_V1.0
- 31 -
L70 Hardware Design
6.4. Bottom view of the module
18
1
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10
9
Figure 21: Bottom view of the module
L70_HD_V1.0
- 32 -
L70 Hardware Design
7. Manufacturing
7.1. Assembly and soldering
L70 is intended for SMT assembly and soldering in a Pb-free reflow process on the top side of the
PCB. It is suggested that the minimum height of solder paste stencil is 130um to ensure sufficient
solder volume. Pad openings of paste mask can be increased to ensure proper soldering and solder
wetting over pads. It is suggested that peak reflow temperature is 235~245ºC (for SnAg3.0Cu0.5
alloy). Absolute max reflow temperature is 260ºC. To avoid damage to the module when it is
repeatedly heated, it is suggested that the module should be mounted after the first panel has been
reflowed. The following picture is the actual diagram which we have operated.
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℃
Preheat
Heating
Cooling
250
Liquids Temperature
217
200℃
200
40s~60s
160℃
150
70s~120s
100
Between 1~3℃/S
50
0
50
100
150
200
250
300
s
Time(s)
Figure 22: Ramp-soak-spike-reflow of furnace temperature
7.2. Moisture sensitivity
L70 is sensitivity to moisture absorption. To prevent L70 from permanent damage during reflow
soldering, baking before reflow is required in following cases:


Humidity indicator card: At least one circular indicator is no longer blue
The seal is opened and the module is exposed to excessive humidity.
L70_HD_V1.0
- 33 -
L70 Hardware Design
L70 should be baked for 192 hours at temperature 40℃+5℃/-0℃ and <5% RH in low-temperature
containers, or 24 hours at temperature 125℃±5℃ in high-temperature containers. Care should be
taken that plastic tray is not heat resistant. L70 should be taken out before preheating, otherwise, the
tray maybe damaged by high-temperature heating.
7.3. ESD safe
L70 module is an ESD sensitive device and should be careful to handle.
7.4. Tape and reel
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Out direction
Unit: mm
Figure 23: Tape and reel specification
L70_HD_V1.0
- 34 -
Shanghai Quectel Wireless Solutions Co., Ltd.
Room 501, Building 13, No.99, TianZhou Road, Shanghai, China 200233
Tel: +86 21 5108 6236
Mail: info@quectel.com