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|LNSC-2420-cache.lib||1 year ago|
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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.
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.
- 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)
- Solar panel reverse current
- Battery overvoltage
- Battery undervoltage
- Load current limit
The design in this repository is licensed under the CERN Open Hardware Licence Version 2 - Permissive (CERN-OHL-P.