A typical implementation of the thermal monitor is based on a simple voltage comparator: a temperature-independent voltage, [V.sub.REF], usually provided by a bandgap voltage
reference, is applied at one input, while a temperature dependent voltage is applied to the other input of the comparator .
Figure 1 shows a simplified circuit that ADI has used to provide a 1.205-V bandgap voltage reference.
In addition to developing a voltage or current directly proportional to temperature, some of these designs achieve a nominally zero-TC bandgap voltage reference output by adding VBE with a negative TC of about -2mV/[degrees]C to AVBE with a positive TC of about +2mV/[degrees]C.
The topics include voltage reference, error sources in bandgap voltage
reference circuit, temperature compensation techniques, high order curvature correction, and CMOS voltage reference without resistors.
The solutions feature a variety of Intersil ICs, including the ISL28134 low noise, zero-drift op amp, the ISL26102 24-bit delta sigma converter, and the ISL21010 precision bandgap voltage
Physical design, temperature coefficient, bandgap voltage references
[V.sub.GO]: bandgap voltage extrapolated to zero Kelvin
The MAX6126 is an ultra-low 1.3[micro][V.sub.P.P] noise, precision bandgap voltage
reference intended for applications in industrial control, high-resolution 3V or 5V A/D and D/A converters and instrumentation.
The Intersil-Renesas solution provides 24-bit low noise precision signal conditioning with a complete analog-to-digital front-end including the ISL28617, a low noise 40V instrumentation amplifier with integrated ADC driver, the ISL28134, a 5V low noise zero drift op amp, the ISL26102 24-bit delta sigma converter, and the ISL21090, an ultra low noise precision bandgap voltage
reference, among others.