Air-Core Gauge Driver Translates 10-Bit Word To DC

Translating a 10-bit digital word supplied by a µP or µC into a complementary dc output used to control various air-core meters in vehicle instrument panel gauges, CS4172 Single Air-Core Gauge Driver IC provides a resolution of 0.35° and an accuracy of ±1° over the full 360° rotation of the gauge’s pointer indicator. The IC uses a tangential conversion algorithm that converts digital input data from the processor to angle information required to drive the quadrature coils of the gauge. A tangential algorithm creates about 40% higher peak torque in the meter movement than a conventional sine-cosine algorithm. The increased torque reduces the error due to pointer droop at critical angles of 45°, 135°, 225° and 315°. Data words are transferred over a serial-parallel interface bus at a clock rate up to 2 MHz. An internal serial-to-parallel shift register sends the data to a 10-bit DAC whose output is fed to a multiplexer that generates a combination of voltages representing the tangent function that go to output buffers and then drive the meter coils. Each output buffer can supply up to 80 mA per coil.