Application Notes

R01AN5377EJ0200 Rev.02.00 Page

of 39

Nov.10.21

RX23E-A Group

Analog Front End Typical Characteristics

Summary

This document describes typical analog characteristics of 24bit Δ-Σ A/D converter (DSAD) and Analog Front

End (AFE) integrated in RX23E-A.

Measurement conditions are described as below, unless otherwise specified.

AVCC0=5V, Ta=25°C, External VREF=2.5V, Normal mode, OPCR.DSADLVM bit=0 (*1)

See below for the meaning of abbreviations contained in this document.

Gain=1(DSAD) : PGA disabled / Buffer disabled

Gain=1(BUF) : PGA disabled / Buffer enabled

Gain=1(PGA) : PGA enabled / Buffer enabled

PRB : Positive Reference Buffer

NRB : Negative Reference Buffer

Target Device

RX23E-A

*1 OPCR.DSADLVM bit selects the operating voltage for Δ-ΣA/D. When the AVCC0 voltage is lower than 3.6 V, set it

to 1. To use Δ-ΣA/D with high precision, set the AVCC0 voltage to 3.6 V or higher, and set this bit to 0.

VCC

VSS

VCL

RES#

XTAL/P37

EXTAL/P36

GPIO

AIN8/AN002

/VREFL0

Low side power switch

Excitation

current

source

BGR

VBIAS

AVCC0

AVSS0

AIN0

AIN1

AIN2

AIN3

AIN4/REF1N

AIN5/REF1P

AIN6/AN000

AIN7/AN001

LSW

AIN9/AN003

/VREFH0

AIN11/AN005

REFOUT

REF0N

REF0P

12bit

SAR ADC

MUX

Digital

Filter

(SINC4)

24bit

DSADC

Offset/

Gain

calibration

PGA

Digital

Filter

(SINC4)

24bit

DSADC

Offset/

Gain

calibration

PGA

AVSS0

REF1N

REF1P

AVCC0

REFOUT

REF2N

REF2P

VREFL

VREFH

AVSS0

AVCC0

AVSS0

REF1N

REF1P

AVCC0

Memory

RXv2 32MHz

FPU

Flash memory

128KB–256KB

RAM

16K–32KB

E2 Data Flash

8KB

Serial I/F

Bus control

DMAx4 DTC

Clock

HOCO (32MHz)

Main-clock

(1–20MHz)

LOCO (4MHz)

ILOCO (15kHz)

PLL

(up to 32MHz)

Timer

Other function

Safety function

IWDT

CAC

AD check

DOC

POE2

CRC

SCIx4 RIIC

RSPI CAN

MTU2 x6 TMR x4

CMT x2

LPT

POR LVD

ELC

MPC

Temp

Sensor

RX23E-A Group Analog Front End Typical Characteristics

R01AN5377EJ0200 Rev.02.00 Page

of 39

Nov.10.21

Contents

1. RX23E-A Analog Front End Features ...................................................................................... 4

2. 24bit Delta-Sigma A/D Converter ............................................................................................. 5

2.1 Noise histogram, Time domain waveform ............................................................................................. 5

2.2 Integral nonlinearity error (INL) ............................................................................................................. 7

2.3 Offset error histogram ........................................................................................................................... 9

2.4 Offset error temperature drift ............................................................................................................... 11

2.5 Offset error - Input common mode voltage ......................................................................................... 12

2.6 Gain error histogram ........................................................................................................................... 14

2.7 Gain error temperature drift ................................................................................................................. 16

2.8 RMS noise – Input differential voltage ................................................................................................ 17

2.9 RMS noise VREF dependence histogram .......................................................................................... 18

2.10 RMS noise – Date rate ........................................................................................................................ 21

2.11 Effective resolution－Date rate ............................................................................................................ 22

2.12 Noise table (Normal mode) ................................................................................................................. 23

2.13 Noise table (Low power mode) ............................................................................................................ 24

2.14 Common Mode Rejection Ratio (CMRR) ............................................................................................ 25

3. Voltage Reference (VREF) .................................................................................................... 26

3.1 Initial accuracy, Temperature drift, Load regulation ............................................................................ 26

4. Excitation Current Source (IEXC) .......................................................................................... 27

4.1 Initial accuracy, Current matching ....................................................................................................... 27

4.2 Temperature drift ................................................................................................................................. 28

4.3 Drift matching ...................................................................................................................................... 29

4.4 Load regulation .................................................................................................................................... 30

5. Temperature sensor (TEMPS) ............................................................................................... 30

5.1 Temperature error ............................................................................................................................... 30

6. 24-bit Delta-Sigma A/D Converter Analog Input ..................................................................... 31

6.1 Input current temperature dependence ............................................................................................... 31

6.2 Input bias current – Input voltage ........................................................................................................ 32

6.3 Input offset current - Input voltage....................................................................................................... 33

7. External Reference Input ....................................................................................................... 34

7.1 Input current temperature dependence ............................................................................................... 34

7.2 Input current – Input voltage ................................................................................................................ 34

8. Operating Current .................................................................................................................. 35

8.1 24-bit Delta-Sigma A/D converter operating current – AVCC0 ........................................................... 35

8.2 24-bit Delta-Sigma A/D converter operating current temperature dependence .................................. 35

8.3 Buffer operating current temperature dependence ............................................................................. 36

8.4 Voltage reference (VREF), Temperature sensor (TEMPS), Bias voltage generator (VBIAS),

Excitation current source (IEXC) ......................................................................................................... 36