Electronics Weekly Electronics Design & Components Tech News
Called MAX40056 it is intended to reduce vibration in motor drives.
The claim is that it can reject PWM slew rates of >500V/µs and settles within 500ns to provide a 0.3% accurate (of full-scale) measurement of winding current “allowing motor control designers to increase drive frequency or decrease minimum duty cycle without sacrificing measurement accuracy”, said Maxim, saying that accurate winding current measurement at low duty cycle helps reduce vibration when the motor is running at a slow speed.
Common mode range is -0.1V to +65V and it is protected across -5V to 70V – from inductive spikes, for example.
Ac common-mode rejection ratio (CMRR) is 60dB (50V ±500V/µs PWM edges), and dc CMRR is 140dB. This is coupled with a 5µV (typ) input offset voltage and 300kHz -3dB bandwidth.
Gain options include 10, 20 and 50V/V, there is a 1% 1.5V internal reference, and the output is rail-to-rail.
The reference is used to offset the output to indicate the direction of the sensed input current, and has enough drive to source current into external loads – an adjoining differential ADC, for example. For higher supply voltages and higher full-scale output swings, the internal reference can be overridden by a higher voltage external reference.
Either the internal or an external reference can be used to define the trip threshold for the integrated over-current comparator to indicate a fault condition.
The chip needs a separate single power supply between 2.7 and 5.5V and operates over -40°C to +125°C.
Packaging is 2.02 x 1.4mm WLP-8 or 8-pin μMAX.
Intended uses include: battery stack monitors, current monitoring of inductive loads, PWM H-bridge motor current sensing (in-line, in-phase, winding) and solenoid current sensing.
