ET-S39
ATM90E32 3-Phase Energy Monitor
3-phase energy metering IC with CT inputs
AED 219.00
Out of stockOverview
3-phase energy metering IC with CT inputs
The ET-S39 is built around the Microchip ATM90E32AS — 3 voltage + 3 current ΣΔ channels, active/reactive/apparent energy, ±0.1% active energy over 6000:1, RMS, frequency, phase angle, THD. It connects over SPI (mode 3) on J3. No Qwiic (SPI part) and is powered from VIN 3.3–5.5V, onboard LDO.
Designed in Dubai by ElectroTrical — the full schematic, BOM and design notes are published below.
Good for
- 3-phase energy metering
- Workshop and factory monitoring
- Solar inverter monitoring
Key features
What makes it different
IC
Microchip ATM90E32AS: 3 voltage + 3 current ΣΔ channels, active/reactive/apparent energy, ±0.1% active energy over 6000:1, RMS, frequency, phase angle, THD
Inputs
3× 3.5mm CT jacks (SCT-013-000 100A:50mA) + 3× screw terminals for 9–12VAC wall transformers (one per phase, or one shared for single-phase)
Interface
SPI (mode 3) on J3. No Qwiic (SPI part)
Supply
VIN 3.3–5.5V, onboard LDO
Open documentation
Schematic, BOM and layout notes published for every board.
Breadboard friendly
Standard 2.54 mm pitch and M2.5 mounting holes.
Specifications
Technical specifications
| IC | Microchip ATM90E32AS: 3 voltage + 3 current ΣΔ channels, active/reactive/apparent energy, ±0.1% active energy over 6000:1, RMS, frequency, phase angle, THD |
|---|---|
| Inputs | 3× 3.5mm CT jacks (SCT-013-000 100A:50mA) + 3× screw terminals for 9–12VAC wall transformers (one per phase, or one shared for single-phase) |
| Interface | SPI (mode 3) on J3. No Qwiic (SPI part) |
| Supply | VIN 3.3–5.5V, onboard LDO |
| Safety | No mains connection on this board. Voltage comes only from plug-in low-voltage AC transformers; CTs clip around insulated wires |
| Size | 76.2 × 50.8 mm |
|---|---|
| Mounting | 4 × M2.5 holes, 2.54 mm from each corner |
| Connectors | 13-pin 2.54 mm header · Screw terminal 2P 5.0mm 17A (THT) — Phase A AC transformer input · Screw terminal 2P 5.0mm 17A (THT) — Phase B AC transformer input · Screw terminal 2P 5.0mm 17A (THT) — Phase C AC transformer input |
| Main IC | ATM90E32AS-AU-R (LCSC C177153) |
| Revision | Rev B |
| Libraries | CircuitSetup ATM90E32 Arduino library, ESPHome atm90e32 (native component) |
|---|
| JP1 (default Closed) | Cut to turn off the LED |
|---|
Performance
Accuracy compared
Pinout
Pin map and connections
| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | VIN | Power | 3.3–5.5V |
| 2 | 3V3 | Power | LDO output |
| 3 | GND | Ground | Ground |
| 4 | CS | SPI | SPI chip select, active low |
| 5 | SCLK | SPI | SPI clock ≤ 200kHz recommended |
| 6 | SDI | SPI | MOSI |
| 7 | SDO | SPI | MISO (3.3V out) |
| 8 | IRQ0 | Signal | IRQ0 |
| 9 | IRQ1 | Signal | IRQ1 |
| 10 | WARN | Output | WarnOut |
| 11 | CF1 | Signal | Active energy pulse |
| 12 | ZX0 | Signal | Zero crossing |
| 13 | RESET | Control | Active low |
Mechanical
Dimensions and what's in the box
In the box
- 1 × ET-S39 ATM90E32 3-Phase Energy Monitor (assembled)
- 1 × 13-pin 2.54 mm male header, unsoldered
Getting started
- Wire the header: VIN, 3V3, GND, CS, SCLK, SDI
- Libraries: CircuitSetup ATM90E32 Arduino library, ESPHome
atm90e32(native component)
Compare
Which current and power board?
| ATM90E32 3-Phase Energy Monitor (this board)This board | ET-S07 INA228 85 V Power Monitor | ET-S37 ACS725 ±20 A Current Sensor | ET-S38 2-Channel CT Clamp Interface | |
|---|---|---|---|---|
| What it does | 3-phase energy metering IC with CT inputs | 20-bit current, voltage, power and energy monitor | Isolated Hall current sensor with 16-bit I²C ADC | SCT-013 clamp interface with 16-bit I²C ADC |
| Interface | SPI (mode 3) on J3. No Qwiic (SPI part) | I²C 0x40 default; 0x41/0x44/0x45 via JP3/JP4 (16… | I²C 0x48; raw analog VIOUT also on J3.6 | I²C 0x48 |
| Best for | 3-phase energy metering | Battery and solar monitoring | Motor current monitoring | Home energy monitoring |
| Price | 219 AED | 59 AED | 49 AED | 49 AED |
Downloads
Documents and design files
Need a custom version of this board?
Different connector, size or sensor? We design and build custom variants.