POWER Revolutionising Industrial Power Supply:
The ZXCT21x Series Unveils a New
By Steve Hsiao, WW strategic technical marketing, Diodes Incorporated I
n the rapidly evolving landscape of industrial power supply and USB Power Delivery (PD) and reliable current sensing solutions has never been more critical. Enter the ZXCT21x series, a new lineup of dedicated current engineers approach current measurement in applications ranging from laptops and docking stations to portable chargers. This article explores the common challenges faced in current sensing, the limitations of traditional discrete component solutions and how the ZXCT21x series emerges as a superior alternative, promising to streamline the design performance across a spectrum of industrial and consumer applications.
The ZXCT21x devices are for power rails below 26V, high-side or low-side sense for both uni- and bi-directional applications. Target applications include battery management systems for measuring charge and discharge currents in batteries, monitoring the average current of a motor for speed control and protection, monitoring the output current of a power supply for regulation and overload protection, measuring the panel current to enhance solar power system performance, monitoring currents in various industrial automation equipment for control and diagnostics and measuring battery drain current and optimising power usage of portable electronic devices.
With discrete components, achieving the same level of accuracy as dedicated current The circuit design becomes more complex, requiring several passive components and careful op amp selection to meet the desired gain, bandwidth and common-mode rejection ratio (CMRR) (see Figure 1). In a typical discrete circuit, which uses four gain resistors and an op amp, you would
need to match the resistor tolerances. Adding further complexity, discrete solutions often require manual calibration to compensate for component variations and drifts. Also, as input op amp offset voltage varies with temperature, dealing with offset drift becomes challenging, negatively impacting accuracy. In addition, discrete components might offer a different level of performance than a ZXCT21x, in terms of noise, offset voltage and power consumption.
offers several advantages. The ZXCT21x devices are easy to use and require minimal external components. The ZXCT21x is designed achieves high accuracy due to careful calibration and internal compensation techniques. Compared to discrete solutions, they offer good noise performance, low offset voltage and low power consumption. More importantly, while discrete components might seem cheaper initially, the cost of design complexity, calibration effort and potential
performance compromises might outweigh the savings.
However, the ZXCT21x should only be considered for high-side sensing of power rails below 26V, due to the 26V common-mode
voltage (VCM(max)) limitation. Conversely, the negative voltage sense should be higher
than -0.3V due to its VCM(min) limitation. The device should also not be considered for monitoring a dynamic switching current from an inductive load, due to its limited bandwidth of 4kHz to 80kHz.
The maximum current that the ZXCT21x can
with an Isens of 100A and Rsens maximum Vsens would be 10mV. The current measurement resolution is dependent on the gain selected, 50, 75, 100, 200, 500 or 1000, and
the reference voltage (Vref). As a general rule, the lower the gain, the higher the resolution, but the output voltage is lower. Hence, when you are designing the circuit, you must consider the trade-off between the resolution and dynamic range.
The ZXCT21x operates on a single supply between 2.6V and 26V and its maximum
Figure 1: Component selection, calibration and performance are important considerations for discrete solutions.
34 DECEMBER/JANUARY 2025 | ELECTRONICS FOR ENGINEERS
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54
