Building a Monophasic TENS Device for the Hand
I’ve always been fascinated by the intersection of electronics and the human body —how a few carefully shaped pulses can interact with nerves and muscles. Recently, I built a monophasic TENS (Transcutaneous Electrical Nerve Stimulation) device for a family member, specifically tailored for the hand.
🔋 Power Stage
The heart of any stimulator is its power supply. I started with a 3.7V LiPo battery as the energy source, managed by the MCP73831 charger IC. This gave me a simple USB-C charging interface and safe single-cell management.
From there, I needed two rails:
+3.3V logic rail for the microcontroller and digital circuitry
for the microcontroller and digital circuitry High-voltage rail (~32V) for the stimulation pulses
The TPS55340 boost converter handled the heavy lifting, stepping the battery voltage up to 32V. Careful selection of inductors (100 µH for the boost stage).
While the boost converter gave me the high-voltage stimulation rail, the digital brain needed a clean and stable 3.3V supply. For that, I used the TPS63001 buck‑boost converter from TI.
Why this choice?
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