Lierda TB25 Series LoRaWAN Node Module Hardware Design Manual
Hardware Specification
LoRa Standard Module
Module Type: L-LRNTB25-97UN4
Legal Statement
By receiving this document from Lierda Technology Group Co., LTD. (hereinafter referred to as "Lierda"), you agree to the following terms. If you do not agree to the following terms, please stop using this document.
The copyright of this document is reserved by Lierda Technology Group Co., LTD. Any rights not expressly granted in this document are reserved. The documents contain proprietary information about Lierda. Without the prior written permission of Lierda, no entity or individual may copy, transmit, distribute, use or disclose this document and any pictures, forms, data and other information contained in this document.
The product complies with the design requirements of environmental protection and personal safety. The storage, use and disposal of the product shall be carried out in accordance with the requirements of the product manual, relevant contracts or relevant laws and regulations.
The Company reserves the right to modify and improve the products described in this manual without prior notice; We reserve the right to revise or withdraw this manual at any time.
Document Revision History
| Version | Change date | Reviser | Auditor | Change content |
|---|---|---|---|---|
| Rev1.0 | 2023-10-19 | wfy | lxy | Initial release |
1 Introduction
This document defines the standard application development specifications for the L-LRNTB25-97UN4 module (hereinafter referred to as the module), and describes its hardware interfaces, electrical characteristics, application methods, and mechanical specifications.
This document can help users quickly understand the hardware interface specifications, electrical, mechanical characteristics and other related information of the module. Combined with other relevant documents, you can quickly master the application development method of the module.
2 Product Overview
The L-LRNTB25-97UN4 is a LoRaWAN End Node module developed by Lierda Internet of Things Technology Co., LTD. The module uses a serial interface to exchange data and instructions with user equipment, which can easily provide users with fast LoRaWAN network access and wireless data transmission functions. The module supports three working modes: sleep, receive, and transmit. Users can choose the appropriate working mode according to their own application scenarios. The module has many characteristics, such as a wide transmitting power range, low receiving sensitivity, and strong anti-interference ability.
2.1 Product Features
| Main Parameters | Instructions |
|---|---|
| Operating frequency | 860~930MHz |
| Modulation mode | LoRa |
| Receiving sensitivity | -124dBm@PER=5%_SF7_BW125 |
| Maximum transmitting power | 22dBm@25°C |
| Communication interface | UART |
| Supply voltage | DC 3.3V |
| Transmit current | Avg.120mA@TX power_22dBm Avg.8.5mA@RX |
| Dimension | 17.7×15.8×2.4mm |
| Operating temperature | -40~+85°C |
2.2 Hardware Block Diagram
The hardware block diagram illustrates the core components: a STM32 L051 microcontroller connected via SPI to the SX1262 LoRa transceiver. The SX1262 interfaces with a matching network and a SWITCH (SPDT) for antenna control. Key interfaces include VDD, GND, UART, SPI, RESET, and general I/O pins. The ANT pin is dedicated for antenna connection.
2.3 Pin Definition
The pin distribution diagram visually maps pin numbers (1-44) to their functions. It highlights power (VDD, GND), communication (UART TX/RX, SWDIO, SWCLK), control (RESET_N, BOOT), and RF (ANT_RF) pins. Various pins are designated as 'NC' (No Connect) or functional I/O. A legend clarifies pin types: 'POWER', 'GND', 'UART', 'SWD', 'Functional', 'Antenna', 'IO', and 'Unused'.
2.4 Module Pin Description
2.4.1 UART
| Pin Name | Pin No. | Instructions | Pin Type | Dc characteristic | Remarks |
|---|---|---|---|---|---|
| UART_TXD | 17 | UART | O | - | - |
| UART_RXD | 18 | UART | I | - | - |
| DEBUG_RXD | 38 | UART | I | - | - |
| DEBUG_TXD | 39 | UART | O | - | - |
2.4.2 Power
| Pin Name | Pin No. | Instructions | Pin Type | Dc characteristic | Remarks |
|---|---|---|---|---|---|
| VDD | 42, 43 | Power | PI | Vmin= 2V Vtype= 3.3V Vmax= 3.7V | - |
| VDD_EXT | 24 | Power | PO | - | - |
| GND | 1, 10, 27, 34, 36, 37, 40, 41, 56, 57, 58 | GND | G | - | - |
2.4.3 SWD
| Pin Name | Pin No. | Instructions | Pin Type | Dc characteristic | Remarks |
|---|---|---|---|---|---|
| SWDIO | 2 | SWD | I/O | - | - |
| SWCLK | 3 | SWD | I | - | - |
2.4.4 Functional Pin Interfaces
| Pin Name | Pin No. | Instructions | Pin Type | Dc characteristic | Remarks |
|---|---|---|---|---|---|
| P0 | 4 | Reserve | I/O | - | Default high resistance state |
| P1 | 5 | Reserve | I/O | - | Default high resistance state |
| P2 | 6 | Reserve | I/O | - | Default high resistance state |
| BOOT | 7 | - | I | - | Default low |
| P3 | 8 | Reserve | I/O | - | Default high resistance state |
| RESET_N | 15 | Reset | I | - | Active low |
| WAKE | 19 | - | I | - | - |
| MODE | 20 | - | I | - | - |
| STAT | 21 | - | O | - | Default high |
| BUSY | 22 | - | O | - | Default high |
| NC | 9, 11, 12, 13, 14, 16, 23, 25, 26, 28, 29, 30, 31, 32, 33, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55 | NC | - | - | NC |
2.4.5 ANT
| Pin Name | Pin No. | Instructions | Pin Type | Dc characteristic | Remarks |
|---|---|---|---|---|---|
| ANT_RF | 35 | ANT | I/O | - | - |
Pin type: "O"=Output, "I"= Input, "P"=Power, "G"=Ground
3 Operating Characteristics
3.1 Working Mode
| Working mode | Module state |
|---|---|
| Normal working mode | Networking status, Users can initiate communication through serial port commands |
| Sleep mode | In low-power state, the user needs to wake up the module and then initiate communication through the serial port command |
3.2 Power Supply Circuit
VDD is the input end of the whole module power supply, and the power supply directly affects the performance of the module. During the design, a power supply capable of providing at least 0.3A current must be selected to ensure that the input voltage to the VDD is not lower than the minimum operating voltage to prevent abnormal operation of the module due to voltage drop.
If the pressure difference between the input voltage and the power supply voltage of the module is not very large, it is recommended to choose LDO as the power supply. If there is a relatively large pressure difference between the input and output, DC-DC is used for power conversion, and EMI problems caused by DC/DC should be paid attention to.
The power wiring is as short as possible and the GND plane of the power supply part should be as complete as possible and have more ground holes, and the capacitor should be as close as possible to the VDD pin of the module.
3.3 RESET
The reset pin of the module remains at a low level of 100 subtle or above, and the module is reset.
4 Typical Reference Design Circuit
The following is the typical design circuit of the module, and the use of other pins should be adjusted according to the actual application requirements.
When the VDD of the module is 3.3V, if the terminal serial port is not 3.3V level, the serial port level conversion circuit needs to be added.
The typical reference design circuit schematic shows how the L-LRNTB25-97UN4 module can be integrated. It depicts connections for power (VDD, GND), serial communication (UART TX/RX), and antenna. Supporting components like capacitors (C1-C4) and resistors (R1) are shown. A terminal block is included for serial interface access, and a level shifter may be required if the host system's serial voltage differs from 3.3V.
5 Specification Parameter
5.1 Absolute Maximum Ratings
Only the maximum load that can be borne is given here, and it does not mean that the functional operation of the device under these conditions is correct. The reliability of the device may be affected if the device works at the maximum value for a long time.
| Main Parameters | Minimum | Maximum | Units | Remarks |
|---|---|---|---|---|
| Supply voltage | -0.3 | +3.9 | V | - |
| Max RF input power | - | +10 | dBm | ANT port |
5.2 Operating Range
| Main Parameters | Minimum | Typical | Maximum | Units | Remarks |
|---|---|---|---|---|---|
| Supply voltage | +2 | +3.3 | +3.7 | V | - |
| Operating temperature | -40 | - | +85 | °C | - |
| Storage temperature | -40 | - | +85 | °C | - |
Digital Logic Level Characteristics
| Main Parameters | Minimum | Typical | Maximum | Remarks |
|---|---|---|---|---|
| VIH(V) | 0.7*VDD | - | - | - |
| VIL(V) | - | - | 0.3*VDD | - |
| VOH(V) | VDD-0.45 | - | - | 2V≤VDD≤3.7V |
| VOL(V) | - | - | 0.4 | - |
Radio-frequency Parameter
| Main Parameters | Minimum | Typical | Maximum | Units | Remarks |
|---|---|---|---|---|---|
| Operating frequency | 860 | - | 930 | MHz | The module hardware supports the 860-930MHz band. The specific operating band is selected according to the user's software configuration. |
| TX power | 20.5 | 21 | 22 | dBm | VDD=+3.3V@25°C; At 25 °C, the operating voltage VDD ≥ 3.2V, the maximum transmitting power ≥20.5dBm; When 2.7V ≤ VDD < 3.2V, the maximum transmit power ≥ 17.5dBm; When 2V ≤ VDD < 2.7V, the maximum transmitting power is ≥14.5dBm; |
| Transmit current | - | 120 | 135 | mA | TX power@22dBm |
| Sleep current | - | 2 | 3 | uA | - |
| Receiving sensitivity | -125 | -124 | -123 | dBm | SF7_BW125 |
Note
- The test conditions are: temperature: 25°C, center frequency: 863.1MHz/902.1MHz, working voltage: 3.3V; Unless otherwise specified, all test temperatures are 25°C, the same below.
- The user can configure the working frequency band according to the local regulations of the terminal market, and must comply with the local regulations. If the frequency band is not allowed by the regulations, our company does not assume any responsibility. For domestic terminal market applications, please refer to the Catalogue and Technical Requirements of Micro-power Short-range Radio Transmission Equipment.
6 Mechanical Dimension
6.1 Dimension Drawing
Mechanical dimension drawings provide the physical specifications of the module. The top layer view shows a square footprint with rounded corners, detailing overall width and length (17.7x15.8 mm) and pad dimensions. The bottom layer view illustrates the pin grid array (PGA) layout, indicating the arrangement and spacing of the pins.
7 Operation Instruction
7.1 Steel Mesh Opening Design
In principle, the thickness selection of the steel network on the bottom plate is selected according to the comprehensive consideration of the packaging type of the devices in the plate, and the following requirements should be focused on:
The module pad position can be locally thickened to 0.15~0.20mm to avoid air welding.
7.2 Reflux Welding Operation Instruction
Note: This operation instruction is only suitable for lead-free operations and is for reference only.
The Reflux welding operation instruction presents a temperature profile graph and a table for automated soldering. The graph outlines temperature stages: Ramp-up (150-180°C, 60-120 sec), Soaking Zone (150-180°C, 45-90 sec), and Peak Temp (240°C), with specific temperature ranges for top and bottom layers. The table details conveyor speed (900 mm/min) and critical temperature parameters like peak temperature (240±5°C), preheat temperature range (150-180°C), and cooling slope (<4°C/s). It also lists required tools such as a thermometer and heat-resistant gloves.
Federal Communication Commission (FCC) Radiation Exposure Statement
When using the product, maintain a distance of 20cm from the body to ensure compliance with RF exposure requirements.
This device complies with part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.
NOTE: The manufacturer is not responsible for any radio or TV interference caused by unauthorized modifications or changes to this equipment. Such modifications or changes could void the user's authority to operate the equipment.
NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
- Reorient or relocate the receiving antenna.
- Increase the separation between the equipment and receiver.
- Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
- Consult the dealer or an experienced radio/TV technician for help.
ORIGINAL EQUIPMENT MANUFACTURER (OEM) NOTES
FCC Caution: Any changes or modifications not expressly approved by the party responsible for compliance could void the user's authority to operate this equipment.
The OEM must certify the final end product to comply with unintentional radiators (FCC Sections 15.107 and 15.109) before declaring compliance of the final product to Part 15 of the FCC rules and regulations. Integration into devices that are directly or indirectly connected to AC lines must add with Class II Permissive Change.
The OEM must comply with the FCC labeling requirements. If the module's label is not visible when installed, then an additional permanent label must be applied on the outside of the finished product which states: "Contains transmitter module FCC ID: 2AOFDL-LRNTB25". Additionally, the following statement should be included on the label and in the final product's user manual: "This device complies with Part 15 of the FCC Rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interferences, and (2) this device must accept any interference received, including interference that may cause undesired operation."
The module is allowed to be installed in mobile and portable applications. A module or modules can only be used without additional authorizations if they have been tested and granted under the same intended end-use operational conditions, including simultaneous transmission operations. When they have not been tested and granted in this manner, additional testing and/or FCC application filing may be required. The most straightforward approach to address additional testing conditions is to have the grantee responsible for the certification of at least one of the modules submit a permissive change application. When having a module grantee file a permissive change is not practical or feasible, the following guidance provides some additional options for host manufacturers. Integrations using modules where additional testing and/or FCC application filing(s) may be required are: (A) a module used in devices requiring additional RF exposure compliance information (e.g., MPE evaluation or SAR testing); (B) limited and/or split modules not meeting all of the module requirements; and (C) simultaneous transmissions for independent collocated transmitters not previously granted together.
This Module is full modular approval, it is limited to OEM installation ONLY. Integration into devices that are directly or indirectly connected to AC lines must add with Class II Permissive Change. (OEM) Integrator has to assure compliance of the entire end product include the integrated Module. Additional measurements (15B) and/or equipment authorizations (e.g. Verification) may need to be addressed depending on co-location or simultaneous transmission issues if applicable. (OEM) Integrator is reminded to assure that these installation instructions will not be made available to the end user.
