CS4172

CS4172 CS4172 Single Air-Core Gauge Driver Description The CS4172 is a monolithic BiCMOS integrated circuit used to translate a digital 10-bit word from a microprocessor/microcontroller to complementary DC outputs. The DC outputs drive an air-core meter commonly used in vehicle instrument panels. The 10 bits of data are used to linearly control the quadrature coils of the meter directly with a 0.35¡ resolution and ±1.0¡ accuracy over the full 360¡ range of the gauge. The interface from the microcontroller is by a Serial Peripheral Interface (SPI) compatible serial connection using up to a 2MHz shift clock rate. The digital code, which is directly proportional to the desired gauge pointer deflection, is shifted into a DAC and multiplexer. These two blocks provide a tangential conversion function to change the digital data into the appropriate DC coil voltage for the angle demanded. The tangential algorithm creates approximately 40% more torque in the meter movement than does a sin-cos algorithm at 45¡, 135¡, 225¡, and 315¡ angles. This increased torque reduces the error due to pointer droop at these critical angles. Each output buffer is capable of supplying up to 80mA per coil and are controlled by a common enable pin. When OE is low the output buffers are turned off but the logic portion of the chip remains powered and continues to operate normally. The Serial Gauge Driver is self-protected against output short circuit conditions. The output drivers are disabled anytime the...