Electronics Weekly Electronics Design & Components Tech News
They are the standard INA791B (right) and the PWM residue rejecting INA790B (below).
“High-precision measurements are enabled by matching the shunt resistor value and the current-sensing amplifier gain across temperature,” according to TI. “Enhanced PWM rejection reduces the effect of common-mode transients on the output signal. Large ΔV/Δt common-mode transients associated with PWM signals are employed in applications such as motor or solenoid drive and switching power supplies.”
Both have on-board shunt resistors, offer 1MHz small signal bandwidth, 1.8V/µs slew rate, and come in 6 x 6mm VQFN 15 packaging – bandwidth and slew rate drop to 500kHz and 1.5V/µs if gain=4.
Max gain error is ±1%, ±75ppm/°C and max offset is ±375mA ±1.25mA/°C. Higher performance versions are planned – swap the ‘B’ suffix for ‘A’ to get ±0.35% ±35ppm/°C max gain error and ±30mA, ±625µA/°C max offset.
Standard gain is 20mV/A, which can be adjusted continuously up to 400mV/A using external resistors.
If bipolar currents are to be measured, an external op-amp is required to establish a Vcc/2 reference.
The internal current sense resistor is nominally 400µΩ (350 to 500µΩ), which equates to 560µΩ (450 to 650µΩ) across the outside of the package. Inductane is 2nH – all these are at 25°C.
Operation is over -40 to +125°C, and an open-drain alarm activates if the internal junctions reach 160°C.
If the device can be kept to 25°C, its continuous current rating rises to ±75A. Short (223ms) pulses can reach 190A.
It needs its own supply of 2.7 to 5.5V, from which it draws 3.75mA max.
The product pages are:
Unusually, the data sheets have (modest) applications sections – the INA790B version is slightly longer
