USB step-down module (ZCL-B53) (LMR33630ADDA)
The lab’s own design · TI LMR33630ADDA synchronous buck, 400 kHz · in 6–36 V (12 V or 24 V systems) on a 5.5 × 2.1 mm DC jack or a screw terminal · out 5.1 V, 3 A (15 W) on a USB-A port (D+/D− shorted) and a screw terminal · reverse-polarity protected
Try it on the benchThe lab drops it on an empty bench and opens its datasheet card.
Typical part: ZCL-B53 USB step-down module (this lab’s own design, on a TI LMR33630ADDA)
Pins
- DC jack centre (+)
- DC jack sleeve (−)
- IN+ (screw)
- IN− (screw)
- 5V (screw)
- GND (screw)
- USB-A port (5 V out)
Ratings and limits
| Input | 6–36 V operating (it starts at 3.8 V, but needs about 5.3 V to make 5.1 V) · 38 V absolute maximum · 5.5 × 2.1 mm jack (centre +) or screw terminal |
|---|---|
| Output | 5.1 V ± 2 % (FB 1.0 V, 100 kΩ / 24.3 kΩ) · 3 A continuous (15 W) · USB-A and screw terminal in parallel |
| Current limit | about 3.9 A average (high side 4.5 A peak, low side 3.5 A valley) |
| Short circuit | hiccup: off 94 ms, then a 20 ms retry |
| Thermal shutdown | 165 °C, restarts at 148 °C |
| Efficiency (12 V in) | about 94 % at 0.1 A · 95–96 % at 1 A · 92 % at 3 A |
| USB port | D+ and D− shorted (BC1.2 dedicated charging port): phones take their full charging current |
| Protection | reverse polarity (P-channel MOSFET in the + line); no surge clamp: keep it off 24 V truck load-dump spikes |
| Parts | TI LMR33630ADDA · 8.2 µH shielded inductor · 4 × 22 µF + 470 µF 10 V out · 10 µF + 220 nF + 100 µF 50 V in |
How to use it
Car and boat USB outlets, solar USB charging points, and 5 V for an ESP32 or a Raspberry Pi from a 12 V battery. Use the jack or the IN screws, not both at once: they are the same input. The 5V screws and the USB port are the same output.