3 days Ago By Steve Bush
The technology is tunneling magnetoresistance, and the sensors are intended to sit over the current-carrying PCB track to be measured. Output is a voltage linearly proportional to the current, responding within 300ns. There are two base part numbers: “CT455 sensor supports two standard field ranges, allowing it to sense and translate magnetic fields into a linear analog output voltage, while the CT456 supports a pre-programmed 6mT field,” according to the company.
“They are designed to enable current measurements on PCB or bus-bar applications from 80A up to above 800A, depending on the configuration, with best performance advantages in the 80 – 200A range.” That said, the CT456 data sheet shows that also comes in two user-programmable versions: 6 to 8mT, or 12 to 48mT. The CT455 comes in those, plus a pre-programmed ±48mT as well as the pre-programmed ±6mT.
Differential operation allows CT456 to shun external fields. It has “greater than 90% immunity to stray magnetic fields, which thus have almost no impact on the accuracy of the current measurement”, said Allegro. Other variations for each base part give 3.
3 or 5V operation, bi-directional or uni-directional current sensing, and automotive (AEC-Q100 Grade 1) qualification options. The output of bi-directional parts is quiescent at 50% Vdd, while 5V uni-directional parts sit at 0.5V (0.
5 to 4.5V output range), or 0.65V for 3.
3V types (0.65 to 2.65V range).
All types used only use four of their eight pins: Gnd, Vdd, output and a test pin, but SOIC types need the unused pins (‘LDF’ = leadframe) to be grounded externally. The test pin allows calibration (using serial data) before the parameters are permanently transferred to one-time-programmable memory. Gain re-calibration is looks to be possible – but check this in the data sheets if it is important to you.
Operation in all cases is over -40 to +125°C, and CTD455-BB-48B5 and CTD456-BB-06B5 are associated evaluation boards. Web pages: – ( ) – ( ).
