资 源 简 介
LM12454/LM12458/LM12H45812-Bit + Sign Data AcquisiTIon System withSelf-CalibraTIonGeneral DescripTIonThe LM12458, and LM12H458 are highly integrated DataAcquisiTIon Systems. Operating on just 5V, they combine afully-differential self-calibrating (correcting linearity and zeroerrors) 13-bit (12-bit + sign) analog-to-digital converter(ADC) and sample-and-hold (S/H) with extensive analogfunctions and digital functionality. Up to 32 consecutive conversions,using two’s complement format, can be stored inan internal 32-word (16-bit wide) FIFO data buffer. An internal8-word RAM can store the conversion sequence for up toeight acquisitions through the LM12(H)458’s eight-input multiplexer.The obsolete LM12454 has a four-channel multiplexer,a differential multiplexer output, and a differential S/Hinput. The LM12(H)458 can also operate with 8-bit + signresolution and in a supervisory “watchdog” mode that comparesan input signal against two programmable limits.Programmable acquisition times and conversion rates arepossible through the use of internal clock-driven timers. Thereference voltage input can be externally generated for absoluteor ratiometric operation or can be derived using theinternal 2.5V bandgap reference.All registers, RAM, and FIFO are directly addressablethrough the high speed microprocessor interface to either an8-bit or 16-bit data bus. The LM12(H)458 includes a directmemory access (DMA) interface for high-speed conversiondata transfer.Additional applications information can be found in applicationsnotes AN-906, AN-947 and AN-949.
