Rev. 1.0 1/15

Copyright © 2015 by Silicon Laboratories

AN836

AN836

Current Sense Amplifier Performance Comparison:

TS1100 vs. Maxim MAX9634

1. Introduction

Overall measurement accuracy in current-sense amplifiers is a function of both gain error and amplifier input offset

voltage performance. Of the two error sources, amplifier input offset voltage can impact the design more so than

gain error. If the sense resistor needs to be small to maximize power to the load and to minimize power dissipation;

then amplifier input offset voltage becomes the dominant error term. To minimize load current sense error, a

current-sense amplifier with a lower input offset voltage is required. By comparing the TS1100 against the

MAX9634 side-by-side, the TS1100’s 3-to-1 improvement in amplifier input offset voltage translates into a 2x

improvement in current measurement accuracy.

2. Overview

As shown in Table 1, the TS1100 family of current sense amplifiers provides an input offset voltage of only 30 µV

with a gain option of 25, 50, 100, and 200. When compared to the MAX9634, the TS1100 exhibits a factor of three

lower input offset voltage.

The output voltage is a function of the gain and VSENSE. However, due to a finite gain error and input offset

voltage, VOS, the total output voltage is a function of the gain error, VSENSE, and VOS. This is shown in

Equations 1 and 2 below.

Equation 1.

Equation 2.

Table 1. TS1100 and MAX9634 Data Sheet Specifications

TS1100

MAX9634

TS1100

±30 (typ)

±100 (typ)

Gain Error (%)

±0.1%

±0.1%

Gain Options

25

25

50

50

100

100

200

200

V

Gain

V

SENSE



=

V

Gain

V

SENSE



Gain

Gain error



V

SENSE

V

OS









+

=