ZSSC4151C Datasheet

© 2022 Renesas Electronics Corporation

17

March 25, 2020

7.3 Analog Front-End

7.3.1 Overview

The analog front-end (AFE) consists of the multiplexer (MUX), the programmable gain amplifier (PGA), and the analog-to-digital converter

(ADC). The internal offset of the analog front-end is eliminated by an auto-zero compensation.

7.3.2 SCCM

The sensor check and common mode block (SCCM) implements the self-diagnostic features for the analog front-end. The SCCM block provides

the sensor connection checks (short and open circuit) as well as several other diagnostic functions.

7.3.3 Input Multiplexer

The input multiplexer (MUX) selects one of the various inputs and connects it to the signal path utilizing a single ADC. It allows a very flexible

signal routing between the sensor element and the ZSSC4151C.

7.3.4 Programmable Gain Amplifier

The sensor elements signal can be amplified by the on-chip programmable amplifier (PGA) using a gain between 2 and 200. Alternatively, the

PGA can be bypassed and the sensor signal is applied directly to the ADC. The gain is adjustable for every single sensor measurement task

individually in order to provide an ADC input signal span of greater than 50% FS.

Table 6 shows the adjustable gains for the PGA, the corresponding signal spans, and the common mode range limits.

Table 6.

Adjustable PGA Gains and Resulting Sensor Signal Spans and Common Mode Ranges

Requirement

Nominal PGA Gain

aPGA

Maximum Input Span

VIN_SPAN [mV/V]

BR1P and BR1N Input Range [a]

VIN_CM [% VDDA]

Informational

PGA bypassed

800

4 to 96

Informational

2.08

385

30 to 65

Informational

3.15

254

30 to 65

Informational

4.31

186

30 to 65

Informational

6.25

128

30 to 65

Informational

8.31

96

30 to 65

Informational

12.6

63

30 to 65

Informational

17.3

46

30 to 65

Informational

25.0

32

30 to 65

Informational

33.2

24

30 to 65

Informational

50.4

16

30 to 65

Informational

69.0

12

30 to 65

Informational

100.0

8

30 to 65

Informational

138.0

6

30 to 65

Informational

200.0

4 [b]

30 to 65

[a] Recommended range for common mode voltage of bridge (shorted BR1P and BR1P) is 40 to 60%.

[b] Digital zooming allows reducing the input span depending on application requirements.