Relay Control with GPIO
Thought for 2 mins 15 sec
Here’s the comparison (from the datasheets you provided):
Table
| Parameter | Value | Source |
|---|---|---|
| ESP1 High-level source current (IOH) | 40 mA (typical) | ESP32-C3 Datasheet, Table 11 DC Characteristics |
| SRD-05VDC-SL-C Coil current (6 V coil) | 75 mA (nominal) | SRD-05VDC-SL-C Datasheet, Coil Data Chart (6 V) |
| Equivalent 5 V coil current | ≈90 mA (0.45 W/5 V) | SRD-05VDC-SL-C Datasheet (0.45 W power draw) |
| Conclusion | GPIO sourcing 40 mA < relay coil 75–90 mA | Insufficient to drive coil directly |
Because a single GPIO can only source about 40 mA but the relay coil needs on the order of 75–90 mA, you cannot switch these relays directly from [ESP1]’s pins. You’ll need a driver stage (e.g., an N-MOSFET or BJT plus a flyback diode) between the ESP32 and the relay coil.
I need a logic-level N-channel MOSFET to drive the relay. @library find one in SOT-23 footprint for ≥100 mA coil current.
Thought for 2 mins 3 sec
Here are three SOT-23 logic-level N-channel MOSFETs that can comfortably switch a ≥100 mA relay coil:
Table
Recommendation:
- BSS138LT3G offers the lowest RDS(on) at 2.5 V, making it the best choice for 3.3 V GPIO drive.
Which one would you like to add to your design?
Select BSS138LT3G
Select 2N7002
Add BSS123
Check gate charge
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