Bill of materials

UM1737

12/14

DocID025983 Rev 1

6

Bill of materials

7

Conclusion

This document provides the information necessary to develop a low-side current sensing

application using the TSZ121. You can accurately measure current with a limited number of

components even if the sense current is noisy. Moreover, using the TSZ121 high precision

op amp allows you to reduce the shunt resistor value and to increase the schematic gain

without losing accuracy. Thanks to a lower shunt value, there is a lower dissipated power

within the shunt resistor. Consequently, the shunt resistor’s size can be reduced and the

customer can save money.

With the theoretical equations provided, you can easily predict the maximum error on the

output voltage. To minimize errors, you must select the components correctly according to

the parameters described in Section 3.

Table 2. Bill of materials

Part

Footprint

Description

Value

Qty

TSZ121

SOT23-5

Very high accurate amplifier

TSZ121ILT

1

Rf

0603

0.1 % resistor

1. To choose the correct component values, refer to Section 3. The default value has been chosen for a

power source of 5 V, sourcing a maximum current of 1 A

2

Rg

0603

0.1 % resistor

100 Ω

2

Rs

9.4 x 9.1 mm

1 % 4-terminal shunt resistor

10 mΩ(1)

1

Cf

0603

Capacitor

33 nF

1

C1

0603

Decoupling capacitor

22 nF

1