May 2014

DocID025983 Rev 1

1/14

UM1737

User manual

How to use the product evaluation board STEVAL-ISQ014V1 for

low-side current sensing with the TSZ121 operational amplifier

Introduction

This document describes how to use the product evaluation board STEVAL-ISQ014V1 for

low-side current sensing with the TSZ121 operational amplifier (op amp).

Power management mechanisms are found in most electronic systems and power

protection is of vital importance for them. One useful method of protecting an application is

by sensing the current. The low-side current sensing method consists of placing a sense

resistor between the load and the ground of the circuit. The resulting voltage drop is

amplified using the TSZ121.

This user manual describes how to accurately measure the current in your application and

describes the advantages of the low-side current sensing method. In addition, it provides:

• the schematics of the STEVAL-ISQ014V1 evaluation board

• a method for selecting the most appropriate components for your application

• theoretical and practical results

Figure 1. STEVAL-ISQ014V1 product evaluation board

www.st.com