8.2 Thermal Hysteresis
Thermal hysteresis is measured with the REF20xx soldered to a PCB, similar to a real-world application. Thermal hysteresis for the device is defined as the change in output voltage after operating the device at 25°C, cycling the device through the specified temperature range, and returning to 25°C. Hysteresis can be expressed by Equation 1:
- VHYST = thermal hysteresis (in units of ppm),
- VNOM = the specified output voltage,
- VPRE = output voltage measured at 25°C pre-temperature cycling, and
- VPOST = output voltage measured after the device has cycled from 25°C through the specified temperature range of –40°C to 125°C and returns to 25°C.
Typical thermal hysteresis distribution is as shown in Figure 43 and Figure 44.
Figure 43. Thermal Hysteresis Distribution (VREF)
Figure 44. Thermal Hysteresis Distribution (VBIAS)