Medidor De Energia 220v Monofasico Hlw8012 Soic8 Itytarg

HWL8012 Basics

The HWL8012 is a 5V IC that monitors both voltage and current and output RMS voltage, current and active power encoded as a 50% duty cycle square wave where the frequency is proportional to the magnitude.

HLW8012 pinout

Inputs

Current is measured by a differential potential measure across a milli-ohm copper-manganese resistor in series with the main current flow. The differential potential is fed into pins VIP and VIN. The resistor must be such that the wave in VIP-VIN peaks at 43.75mV maximum. A 1milliohm resistor is well suited to measure currents up to ~30A with a dissipation of less than 1W.

Voltage is measured in the same way but since the V2P pin supports up to 495mV RMS signals the potential has to be scaled down. The HLW8012 datasheet recommends a voltage divider of 6 470kOhm resistors upstream and a 1kOhm resistor downstream. That means a scale factor of 2821 that will convert a 230V RMS into 82mV that falls way below the limit.

The product datasheet suggests the circuit below as a typical application and it's the very same schematic you will find on the Sonoff POW (check it's wiki page for a schematic). Except for the fact that the voltage divider in the Sonoff POW has only 5 470kOhm resistors.

HLW8012 typical application

Output

On the MCU side of the IC, we have two pins that output the square wave. The CF pin pulse frequency increases as the active power increase too. The relation depends on the reference voltage (2.43V), the internal clock frequency (3579kHz typically), the voltage divider in the V2P input and the milliohm resistor. For the suggested application in the datasheet a frequency of 1Hz corresponds to a ~12W active power, 10Hz to ~120W, 100Hz to ~1.2kW and so on.

The CF1 pulse is proportional to the RMS current or voltage, depending on the value in the SEL pin. If SEL is pulled high then the CF1 pin outputs a square wave with a frequency proportional to the RMS current measured. If SEL is pulled down it will output the RMS voltage instead. Nominal values (as per datasheet) are 15mA or 0.5V for a 1Hz wave.