|National Semiconductor's LMP8358 simplifies pressure and thermocouple bridge measurements by allowing users to detect shorts, open circuits, and degraded source connections in remote industrial applications. This diagnostic capability prevents circuit shutdowns in medical instruments, precision weigh scales, pressure sensors, and motor control systems.
The LMP8358 uses patented techniques to measure and continuously correct its input offset voltage (1uV typical), eliminating offset drift over time and temperature as well as the effect of 1/f noise. This leads to a flat noise spectrum of 27nV/sqrt Hz. The LMP8358’s programmable frequency compensation enables programmable bandwidths, and its offset compensation circuit does not introduce distortion and aliasing for signals lower than 12kHz of bandwidth.
The LMP8358 is equipped with electromagnetic interference (EMI) suppression filters to reduce unwanted radio frequency (RF) interference from external sources, such as cell phones or nearby antennas. Additional filtering can be added with one external capacitor. The LMP8358 is built on National’s CMOS7-5V process technology and provides an optimized signal path solution for precision systems when combined with the 16-bit ADC161S626 or 14-bit ADC141S626 analog-to-digital converters.
The LMP8358 provides glitch-free transitions between gain settings, which can be programmed to 10, 20, 50, 100, 200, 500, or 1000 through a serial peripheral interface (SPI) or parallel interface. All gain settings have less than 0.1 percent typical gain error. This enables manufacturers to perform system calibration by applying specific signal levels at various gains and temperatures. The LMP8358’s gain can be set to an arbitrary value using two external resistors.