The circuit shown in Figure 1 is a voltage reference with an input over voltage protection. The circuit design and selection of over voltage protection components is optimized for minimum power and maximum input voltage range. Such over voltage protected reference is typically required in portable consumer and wearable medical products like camera lens and sensor modules
Figure 1: Low Power Data Acquisition Block for Skin Impedance Measurement
The input over voltage protection is achieved by standard transistor based regulator. Zener diode Z1 at the base of transistor T1 makes sure output voltage at collector of transistor does not go beyond (VZ – VBE ) This voltage is then fed to TI’s ultra-low power, low drift and low dropout voltage reference REF3330. REF3330 provides accurate voltage which can be used in portable equipment, hard disc drives, wearable medical products, sensor modules, tablets and Smartphones.
To see details REF3330 device performance, click on the below link
To order samples of the REF3330 or other ultra-low power voltage references designed for wearable and portable applications, click on the following product links: