Isolated magnetic current sensor for ≤200A and ≤100V

Called ACS37220, five versions are available, giving a choice of sensitivity (±100, 150 or 200A) and operation voltage (3.3 or 5V) – only the ±200A 3.3V option is not available (see table). Power consumption is up to 15.5mA.

Although the IC is 4 x 4mm, the recommended PCB layout has it sitting in the middle of a 14 x ~29mm rectangle of copper islands.

Inside it a digitally calibrated and compensated analogue signal chain.

The main output is analogue and centred around 1.65 or 2.5V depending on supply voltage (Electronics Weekly has asked if this is Vcc/2 or absolute, watch this space).

Bandwidth is 150kHz (100pF load) and accuracy is given as within ±3.1% over the operating temperature range of -40 to +150°C, and the nominal zero current voltage can vary by ±10mV.

Allegro has gone the extra mile and given these figures over life after AEC-Q100 qualification stresses as: ±4.6% and ±18mV.

Beyond this, input-referred error due to common-mode external fields is typically 2mA/G.

For fast short-circuit protection, a second on-off output is activated above an adjustable current magnitude (sign is ignored). Adjustment is via a single external resistor, or an externally-applied voltage source that can overcome an internal 10μA current source, and the pad can be connected directly to 0V to set the threshold to the nominal full-scale current.

Isolation is rated up to 100V and creepage is 1mm.

Smallest leaded magnetic current sensor

At the same time as revealing the ACS37220 above, Allegro mentioned what it claims will be “industry’s smallest leaded magnetic current sensor”, the ACS37041, which will come in a SOT23-W package and work up to 30A and 100V.