SSP1839 is a built-in clock calibration-free energy measurement chip, suitable for single-phase multi-function energy meters, smart sockets, smart home appliances, electric bicycle charging piles and other applications, and has a high cost performance.
The SSP1839 integrates three high-precision Sigma-Delta ADCs, which can simultaneously measure two currents and one voltage。
SSP1839 can measure current, effective voltage value, active power, active energy and other parameters, and can output fast current effective value (for leakage monitoring or overcurrent protection), as well as temperature detection, waveform output and other functions, through the UART/SPI interface The data can fully meet the needs of smart sockets, smart home appliances, single-phase multi-function energy meters, electric bicycle charging piles and big data collection of electricity consumption information.
Below is an application using this chip to test three-phase voltage:
Picture 1 :Three-phase voltage sampling part
Picture2 SSP1839 Chip connection
Voltage sampling part：
Select the appropriate voltage dividing resistor according to the actual sampling voltage range. See the resistor of picture 1 ，L1 could test the max voltage :0.07*(1950000+510)/510 = 267.7 (V)，L2/L3test the max voltage:0.035*(1950000+240)/240=284.41(V)。
| IP1，IN1 | Analog input of current A channel, maximum differential voltage of pin ±50mV(35mV rms) |
| IP2，IN2 | Analog input of current B channel, maximum differential voltage of pin ±50mV(35mV rms) |
| VP | Voltage signal positive input terminal, maximum differential voltage ±100mV(70mV rms) |
Table 1 The maximum channel sampling value declared in the specification
Chip connection：
This section explains that the chip supports two communication methods, UART/SPI, and you can choose the one that suits you according to your personal needs. For specific register operations, please refer to the specification.
Picture 3 Circuit board drawing
This verification uses UART communication, and the voltage reading is displayed through the upper computer (as shown below) for easy observation.
Note: To set the anti-creep register (0x17) to 00, the default value of the register is 0x0B。
The following table is a few sets of measured data, for reference only.
| Actual voltage（V） | L1 Display（V） | L2 Display（V） | L3 Display（V） |
| 51.94 | 51.96 | 51.92 | 51.86 |
| 83 | 83 | 83 | 83 |
| 101.2 | 101.22 | 101.25 | 101.24 |
| 149.8 | 149.83 | 148.85 | 149.86 |
| 200.4 | 200.43 | 200.45 | 200.36 |
| 219.9 | 219.95 | 220.02 | 219.88 |
As can be seen from the table, the 3-phase voltage test accuracy is very high and can meet the accuracy requirements of general 3-phase voltmeters. The chip can also measure internal temperature, external temperature, and has zero-crossing detection function. For more rich functions and applications, please refer to the specification sheet.
