CN3791 MPPT 3.7V 4.2V Lithium Battery Charging Module

CN3791 MPPT 3.7V 4.2V Lithium Battery Charging Module is a high-efficiency PWM switch-mode single-cell lithium-ion and LiPo battery charger module engineered around the Consonance CN3791 photovoltaic MPPT charge controller IC. Featuring Maximum Power Point Tracking (MPPT) constant-voltage input regulation, this module dynamically tracks the peak power point of solar panels to maximize energy harvesting under fluctuating sunlight conditions. Capable of delivering up to 2A charging current with automatic trickle, constant-current (CC), and constant-voltage (CV) 4.2V termination stages, it is purpose-built for solar-powered IoT nodes, outdoor weather stations, and off-grid lithium battery systems.

Key Features:

• True Solar MPPT Tracking: Constant-voltage MPPT algorithm automatically adjusts charging current to prevent solar panel voltage collapse and extract maximum power.
• High-Efficiency PWM Buck Architecture: Switch-mode step-down topology operates at 300 kHz with up to 94% conversion efficiency and minimal heat dissipation.
• 3-Stage Smart Lithium Charging: Automatically manages deep-discharge trickle pre-charging, high-speed constant-current charging, and 4.2V ±1% constant-voltage termination.
• Automatic Recharge & Sleep Mode: Automatically enters ultra-low-power sleep mode when input solar voltage drops below battery voltage, eliminating reverse leakage.
• Dual Status LEDs: Onboard red (charging in progress) and green/blue (charge complete or standby) SMD LEDs provide clear visual diagnostics.

Technical Specifications:

• Controller IC: Consonance CN3791 MPPT Lithium Charger IC
• Input Supply Voltage:Nominal 6V, 9V, or 12V DC (Solar Panel MPPT Version Specific)
• Target Battery Chemistry: Single-cell (1S) 3.7V Nominal Li-ion / LiPo (4.20V Full Charge)
• Maximum Charging Current: Up to 2.0 A (Determined by onboard current-sense resistor)
• Charge Termination Voltage: 4.20V ± 1%
• Switching Frequency: 300 kHz fixed PWM
• Overvoltage Protection: Integrated battery overvoltage detection
• Operating Temperature Range: -40°C to +85°C

Mechanical Specifications:

• PCB Material: FR-4 Double-Sided Industrial Fiberglass PCB with thermal copper pours
• Input / Output Connectors: 2 × 2-pin JST PH 2.0mm connectors and through-hole solder pads
• Inductor: Shielded SMD power inductor for low EMI radiation
• Weight: Approximately 8 grams

Dimensions:

• Length: 45.0 mm
• Width: 20.0 mm
• Height: 9.5 mm

Pinout and Wiring:

• IN+ (SOLAR+): Positive DC input terminal from solar panel or DC power supply.
• IN- (SOLAR-): Negative ground input terminal from solar panel.
• BAT+ (OUT+): Positive output terminal connecting to 1S 3.7V lithium battery positive pole.
• BAT- (OUT-): Negative output terminal connecting to 1S 3.7V lithium battery negative pole.

Datasheet Reference:

• Refer to the official Consonance Electronics CN3791 MPPT Solar Powered Li-ion Battery Charger IC Datasheet for MPPT resistor calculations and charging curves.

Commonly Used in:

• Solar-powered LoRaWAN, ESP32, and GSM remote environmental monitoring stations
• Autonomous outdoor security cameras, trail cameras, and agricultural soil sensors
• Off-grid portable solar power banks and emergency LED lighting units
• Educational renewable energy and solar MPPT power harvesting demonstrations

Applications:

• Photovoltaic Lithium Charging: Direct high-efficiency charging of 18650, 21700, and LiPo pouch cells from 6V/9V/12V solar panels.
• Unattended IoT Field Nodes: Maintaining continuous battery charge across multi-season outdoor deployments.
• Solar Garden & Street Lamps: Replacing inefficient linear solar charge circuits with switch-mode MPPT control.

Equivalent Models:

• SD05CRMA (CN3791) Mini Solar Charger: Ultra-compact 5V/6V solar MPPT charger module for single-cell 18650 batteries.
• CN3065 Mini Solar LiPo Charger: Linear 500mA solar charger module suitable for lower-power 5V/6V miniature solar panels.
• BQ24650 MPPT Solar Charger: Texas Instruments synchronous switch-mode MPPT charger supporting multi-cell lithium and lead-acid batteries.
• TP5100 2A Switch-Mode Charger: Non-MPPT 1S/2S step-down lithium battery charger for stable DC adapter inputs.

Package Includes:

• 1 × CN3791 MPPT 3.7V 4.2V Lithium Battery Charging Module