By Steve Bush 26th April 2021
A sensor that I somehow missed, despite it being a popular building block in module form is the WCS1800 current sensor from Winson of Taiwan.
It is part of a large family of current sensors from the same company with widely varying characteristics – in this case measuring ±35A dc or 25Arms ac.
Bandwidth is a respectable 23kHz.
The noticeable and neat thing about it, is that the device includes a 9mm diameter hole though which to poke cables. Isolation, according to the data sheet, is 4kV.
Aside from the hole for the current-under-test, the 19.9 x 19.4 x 8mm device only has three pins: oV, +Vcc and output, plus two sturdy solder-in lugs for mechanical strength.
It can operate at anywhere between 3.0V and 12V and sets its zero current output to Vcc/2 (2.35 – 2.65V at 5Vcc). Consumption is typically 3.5mA at 5V (6mA max).
Nominal gain is 66mV/A, and its range is limited by supply voltage as its output can swing to within 300mV of 0V or Vcc – it s with a 5V supply that the ±35A dc or 25A ac operating range is achieved. At 3.3V it is ±20A, but at a different gain as that nominal 66mV/A has a supply voltage dependency.
Gain increases fairly linearly up to just under 100mV/A at 12V, and decreases in a wobbly way to ~40mV/A at 3V. There is a potentially-useful 55mV/A plateau from 3.4V to 4V.
Sensitivity also has a temperature curve, peaking at just above nominal at ~5°C and drooping to 0.7 of nominal at its maximum temperature of +125°C (minimum is -20°C).
With the various variations, a regulated supply voltage and some form of trim for nominal zero and nominal gain would seem quite important.
A thermistor might help do something about the temperature curve – at least to a first order over a limited range – I wonder how much more circuitry would have been needed inside the temperature compensating block to ease this situation? Or why not shift that flattish bit of the curve to around 5V or around 3.3V?
Circuit-wise, resistively-loading the output of WCS1800 is frowned upon – volt meters have to be >100kΩ. A 10 – 100nF capacitor is recommended from output to ground.
Applications are foreseen in motor control, load detection, load management and over-current fault detection.
There are plenty of building-block pcbs based on the device on ebay and from other sources , usually equipped with comparator to set a trip threshold as well.
WCS2200 is a similar 4pin differential output device.
The WCS1800 datasheet is here and there are some application notes
Your email address will not be published. Required fields are marked *
Electronics Weekly teams up with RS Grass Roots to highlight the brightest young electronic engineers in the UK today.
Get our news, blogs and comments straight to your inbox! Sign up for the Electronics Weekly newsletters: Mannerisms, Gadget Master and the Daily and Weekly roundups.
Read our special supplement celebrating 60 years of Electronics Weekly and looking ahead to the future of the industry.
Read the Electronics Weekly @ 60 supplement »
Read the first ever Electronics Weekly online: 7th September 1960. We've scanned the very first edition so you can enjoy it.
Read the very first edition »
Read our special supplement celebrating 60 years of Electronics Weekly and looking ahead to the future of the industry.
Read the Electronics Weekly @ 60 supplement »
Read the first ever Electronics Weekly online: 7th September 1960. We've scanned the very first edition so you can enjoy it.
Read the very first edition »
Tune into this Xilinx interview: Responding to platform-based embedded design
Tune into this podcast to hear from Chetan Khona (Director Industrial, Vision, Healthcare & Sciences at Xilinx) about how Xilinx and the semiconductor industry is responding to customer demands.
By using this website you are consenting to the use of cookies. Electronics Weekly is owned by Metropolis International Group Limited, a member of the Metropolis Group; you can view our privacy and cookies policy here.