Sensing IC Protects Motor Drive Circuits

Light industrial ac and brushless dc motor drives rated up to 230 Vac and appliances such as washing machines and air conditioners are among the typical applications cited for the IR2170, a 600V over-current sensing IC. The chip senses motor current directly through an external sense resistor and reports an error if the current exceeds a preset threshold in both positive and negative polarities. This high-voltage device enables smaller circuit size and reduces component count and includes a 1.5-µs over-current shutdown that works with a wired-OR connection directly to the microcontroller or DSP. The IT2170 requires one mA quiescent current and an input supply voltage range of 7V to 20V. And by sharing the bootstrap supplies with the HVIC gate driver eliminates the need for separate, isolated supplies. The new over-current protection IC comes in either SO-8 or 8-pin DIP package and has a starting price of $0.99 each/100K. Other devices in the IR217x family include the IR2171, which sends a linear current sense output signal in PWM format, and the IR2172, which combines the functions of the IR2170 and IR2171.