47 lines
1.9 KiB
Markdown
47 lines
1.9 KiB
Markdown
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# Hardware for the LNSC-2420 Solar Charger
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The LNSC-2420 is a PWM-based solar charge regulator for 24 V systems supporting
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up to 20 A charging current.
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## WARNING
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The version 1.0 currently in the repository contains **a mistake will destroy the
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driver MOSFETs** (the power MOSFETs are safe)! Do not build it as-is!
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This notice will be removed once the design is fixed.
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## Noteworthy Features
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- High-side switching with N-Channel MOSFETs:
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- Gate voltage is provided by a charge pump which doubles the battery
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voltage.
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- Using N-Channel MOSFETs allows to drastically reduce the Rds\_on compared
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to P-Channel MOSFETs, resulting in lower loss.
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- High-side switching allows to have a shared ground connection between solar
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panel, battery and all devices connected as load.
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- Current and voltage measurement:
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- The solar current, load current, solar voltage, battery voltage and charge
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pump output voltage are measured using the internal ADC of the STM32F030.
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- The voltages are measured via high-resistance voltage dividers which are
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buffered using ultra-low-power OpAmps.
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- Low power usage:
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- The charge pump is disabled if both power FETs are off.
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- Additionally, the microcontroller is put into deep sleep (Stop Mode) if no
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solar power is available and the battery voltage is in undervoltage
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protection.
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- During normal operation (with LEDs on), the controller itself consumes
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below 300 mW.
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- In deep sleep, power consumption is below 25 mW.
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- LED status display:
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- 6 LEDs show the internal charging and discharging state.
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- The LEDs are controlled using Charlieplexing (i.e. only 3 GPIOs are needed)
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- Protections:
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- Solar panel reverse current
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- Battery overvoltage
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- Battery undervoltage
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- Load current limit
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## License
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The design in this repository is licensed under the [CERN Open Hardware Licence Version 2 - Permissive (CERN-OHL-P](LICENSE).
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