Relay Control with GPIO

flux

Here’s the comparison (from the datasheets you provided):

Table

ParameterValueSource
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)
ConclusionGPIO sourcing 40 mA < relay coil 75–90 mAInsufficient 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.
jharwinbarrozo

jharwinbarrozo

I need a logic-level N-channel MOSFET to drive the relay. @library find one in SOT-23 footprint for ≥100 mA coil current.

flux

Here are three SOT-23 logic-level N-channel MOSFETs that can comfortably switch a ≥100 mA relay coil:

Table

PartVDSID (Cont.)RDS(on) @ VGSVGS(th)PdDatasheet
BSS123100 V200 mA7 Ω @ VGS=3 V1–3 V350 mWPDF
2N700260 V200 mA5 Ω @ VGS=4.5 V0.8–3 V200 mWPDF
BSS138LT3G50 V200 mA3.5 Ω @ VGS=2.5 V0.5–1.5 V225 mWPDF
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
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ESP32 power meter 4 ways

ESP32 power meter 4 ways thumbnail
Compact 4-channel power meter using ESP32-C3, ACS712 sensors, ADS1015 ADC, relay control and I²C connectivity for efficient energy monitoring. #PowerMeter #ESP32 #IoT #EnergyMonitoring

Properties

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Pricing & Availability

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