Battery charging module 2-cell - TX5817

This module
is a wide-voltage input charging management chip specifically designed for dual-cell lithium batteries, compatible with 5V and 9V adapters.

With 5V power supply, it achieves boost charging with a maximum battery charging current of 1.5A.
With 9V power supply, it achieves buck charging with a maximum battery charging current of 1A.
The charging current can be set via an external resistor RSET.

Project Parameters
: • Built-in OVP
• High input voltage up to 26V, excellent surge protection
• Automatic recognition of 5V or 9V charger input
• Adaptive input current function
• Minimal external components, supports 2.2μH inductor
• Battery charging current up to 1.5A
• Adjustable charging constant current
• Trickle, constant current, and constant voltage charging modes
• Charging status indication
• NTC battery high and low temperature protection
• Frequency dithering design for ultra-low EMI
• Built-in undervoltage and overtemperature protection
• Lead-free and halogen-free package, ESOP8
Application Areas:
• Bluetooth speakers
• Walkie-talkies
• Smart home
• Power tools
Principle Analysis (Hardware Description) Charging Current

Design Formula: To prevent damage to the chip from transient high voltage during hot-plugging of the charging head, two 22μF capacitors need to be added near the charging interface. Additionally, add a 1μF capacitor near the VIN pin of the TX5817 chip to filter out high-frequency noise. For the VSYS pin, choose a 22μF ceramic chip capacitor and place it as close as possible to the negative end of the Schottky diode. Also, choose a 0.1μF capacitor and place it as close as possible to the VSYS pin. The indicator light status NTC circuit has built-in over-temperature protection, or an external NTC circuit can be used. The calculation formula is as follows: The above diagram shows the application circuit and calculation method for the NTC pin temperature detection of the TX5817. The resistance values ​​of a 10K NTC resistor with a B value of 3950 at the preset high and low temperature protection points are (e.g., at -5℃, RNTC=41.306kΩ, at 50℃, RNTC'=3.588kΩ). Precautions .