JAJSHC9B May 2019 – October 2021 ALM2402F-Q1
PRODUCTION DATA
High-power ac and brushless DC (BLDC) motor-drive applications need angular and position feedback in order to efficiently and accurately drive the motor. Position feedback can be achieved by using optical encoders, hall sensors, or resolvers. Resolvers are the goto choice when environmental or longevity requirements are challenging and extensive.
A resolver acts like a transformer with one primary coil and two secondary coils. The primary coil, or excitation coil, is located on the rotor of the resolver. As the rotor of the resolver spins, the excitation coil induces a current into the sine and cosine sensing coils. These coils are oriented 90 degrees from one another, and produce a vector position read by the resolver to digital converter chip.
Resolver excitation coils can have a very low dc resistance (< 100 Ω), requiring a sink and a source of up to 200 mA from the excitation driver. The ALM2402F-Q1 can source and sink this current while providing current limiting and thermal shutdown protection. Incorporating these protections in a resolver design can increase the life of the end product.
The fundamental design steps and ALM2402F-Q1 benefits shown in this application example can be applied to other inductive load applications, such as dc and servo motors.