SolarLader/LNSC-2420
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A PWM-Type solar charger for 24V systems. Maximum current: 20A
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Thomas Kolb 973d1f0b6f Added resistors to protect the driver MOSFET gates 
These were missing in v1.0 and have been patched in during assembly.
Without R32 and R33, too much voltage difference would be applied to the
gates of the driver transistors Q2 and Q7, destroying the transistors.
2021-06-12 21:58:17 +02:00
.gitignore Initial commit 2021-04-29 23:15:44 +02:00
control.sch Apply license: CERN-OHL-P v2 2021-06-12 21:25:10 +02:00
LICENSE Apply license: CERN-OHL-P v2 2021-06-12 21:25:10 +02:00
LNSC-2420-cache.lib Initial commit 2021-04-29 23:15:44 +02:00
LNSC-2420.kicad_pcb Apply license: CERN-OHL-P v2 2021-06-12 21:25:10 +02:00
LNSC-2420.pro Fixed input polarity of INA139 2021-05-12 21:27:41 +02:00
LNSC-2420.sch Apply license: CERN-OHL-P v2 2021-06-12 21:25:10 +02:00
README.md Apply license: CERN-OHL-P v2 2021-06-12 21:25:10 +02:00
switching.sch Added resistors to protect the driver MOSFET gates 2021-06-12 21:58:17 +02:00

README.md

Hardware for the LNSC-2420 Solar Charger

The LNSC-2420 is a PWM-based solar charge regulator for 24 V systems supporting up to 20 A charging current.

WARNING

The version 1.0 currently in the repository contains a mistake will destroy the driver MOSFETs (the power MOSFETs are safe)! Do not build it as-is!

This notice will be removed once the design is fixed.

Noteworthy Features

  • High-side switching with N-Channel MOSFETs:
    • Gate voltage is provided by a charge pump which doubles the battery voltage.
    • Using N-Channel MOSFETs allows to drastically reduce the Rds_on compared to P-Channel MOSFETs, resulting in lower loss.
    • High-side switching allows to have a shared ground connection between solar panel, battery and all devices connected as load.
  • Current and voltage measurement:
    • The solar current, load current, solar voltage, battery voltage and charge pump output voltage are measured using the internal ADC of the STM32F030.
    • The voltages are measured via high-resistance voltage dividers which are buffered using ultra-low-power OpAmps.
  • Low power usage:
    • The charge pump is disabled if both power FETs are off.
    • Additionally, the microcontroller is put into deep sleep (Stop Mode) if no solar power is available and the battery voltage is in undervoltage protection.
    • During normal operation (with LEDs on), the controller itself consumes below 300 mW.
    • In deep sleep, power consumption is below 25 mW.
  • LED status display:
    • 6 LEDs show the internal charging and discharging state.
    • The LEDs are controlled using Charlieplexing (i.e. only 3 GPIOs are needed)
  • Protections:
    • Solar panel reverse current
    • Battery overvoltage
    • Battery undervoltage
    • Load current limit

License

The design in this repository is licensed under the CERN Open Hardware Licence Version 2 - Permissive (CERN-OHL-P.