STI EVAL-RHFAD128V2 User manual

Introduction
The EVAL-RHFAD128V2 evaluation board allows evaluating the conversion performance of the RHFAD128 eight-channel
analog-to-digital converter, which is designed for 50 ksps to 1 Msps conversion.
The board can accept external signals to measure and evaluate the RHFAD128 conversion performance, based on its
successive approximation register (SAR) with an internal track-and-hold cell.
The board can be supplied in standalone mode. It can also be connected to a NUCLEO-L476RG development board hosting an
STM32 microcontroller, which enables further signal processing and PC communication.
To monitor the EVAL-RHFAD128V2 performance, when connected to the NUCLEO-L476RG, the RHFAD128_GUI can be used.
Figure 1. EVAL-RHFAD128V2 evaluation board
Getting started with the EVAL-RHFAD128V2 evaluation board for the RHFAD128
analog-to-digital converter
UM3160
User manual
UM3160 - Rev 1 - May 2023
For further information contact your local STMicroelectronics sales office. www.st.com

1Getting started
1.1 Features
• RHFAD128 (Rad-hard, 12-bit 1 MHz A-to-D converter)
• Six direct inputs to the RHFAD128 with RC filters (200 Ω / 10 nF)
• Footprint available for external reference with the RHF100 (1) (Rad-hard 1.2 V fixed Vref)
• Footprint available for single op amp RHF43B (2) for current-sensing and custom test
• 2-layer FR4 printed circuit board
• Single ground-layer that proved the best performance
• Decoupling capacitive network close to the ICs to prevent noise on power supplies
• Connectors on the power supplies and on the output for easy plug-in
• Standard SPI communication pinout
• Numerous test-points
1. The RHF100 is not mounted on the EVAL-RHFAD128V2. However, the footprint is available on the board.
2. The RHF43B is not mounted on the EVAL-RHFAD128V2. However, the footprint is available on the board.
1.2 Main components
1.2.1 RHFAD128
The RHFAD128 is a low-power, eight-channel CMOS 12-bit analog-to-digital converter for conversion from 50
ksps to 1 Msps.
The architecture is based on a successive-approximation register with an internal track-and-hold cell.
The RHFAD128 features eight single-ended multiplexed inputs. The output serial data is straight binary and is SPI
compatible.
1.2.2 RHF100
The RHF100 is an adjustable voltage reference with the following features:
• Fixed shunt: 1.2 V stable on capacitive load
• High precision ± 0.15 %
• Wide operating current: 40 μA to 12 mA
• 15 ppm/°C overtemperature range (-45 °C to 125 °C)
• 2 ppm/°C variation over 3000 hrs
• 0.02% precision stability over 3000 hrs
• 300 krad high and low dose rate
• ELDRS-free up to 300 krad
• Mounted in a Flat-10 hermetic ceramic package
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Getting started
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1.2.3 RHF43B
The RHF43B operational amplifier offers high precision functioning with low input. Rail-to-rail output.
It has the following features embedded:
• Bandwidth: 8 MHz gain at 16 V
• Low input offset voltage: 100 μV typ.
• Supply current: 2.2 mA typ.
• Operating from 3 to 16 V
• Input bias current: 30 nA typ.
• ESD internal protection ≥ 2 kV
• Latch-up immunity: 200 mA
• ELDRS free up to 300 krad
• SEL immune at 120 MEV.cm2/mg
• Mounted in a Flat-8 hermetic ceramic package
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Main components
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2How to use the board
To use the board, follow the procedure below.
Step 1. Connect the power generators to AVCC and DVCC connectors.
The allowed voltages for AVCC and DVCC are 2.7 to 3.3 V.
Two ways to power the board:
1. AVCC and DVCC are connected separately by 2 different power supplies.
In this case the resistance R03 is disconnected.
2. AVCC and DVCC are connected to the same power supplies.
In this case the resistance R03 is connected.
Figure 2. AVCC and DVCC connectors
Step 2 Connect the SPI section.
Figure 3. SPI connection pins
Step 3. When using the RHFAD128_GUI GUI, refer to the table below for the connection between the EVAL-
RHFAD128V2 SPI pins and the NUCLEO-L476RG pins.
Table 1. Pinout connection between the EVAL-RHFAD128V2 and the NUCLEO-L476RG
NUCLEO-L476RG pin EVAL-RHFAD128V2 SPI pin
PB12 Chip select
PB13 SCLK
PB14 MISO
PB15 MOSI
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How to use the board
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Step 4. Connect your inputs.
Step 4a. IN1, IN2, IN3, IN4, IN6, and IN7: direct inputs with RC filters (for example 200 Ω / 10 nF is a good
combination at FCLK = 500 KHz).
Step 4b. IN0: input connected to the reference voltage RHF100.
Step 4c. IN5: input connected to a rail-to-rail amplifier RHF43B.
Figure 4. Board section for input connection
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How to use the board
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3Communication with the RHFAD128
3.1 Option A: use the STSW-AKI GUI
The EVAL-RHFAD128V2 can be used with the STSW-AKI GUI. To use it, it is necessary to use a Nucleo-64
L476RG.
The RHFAD128_GUI runs on an STM32 Nucleo-64 development board. It communicates with the RHFAD128 of
the EVAL-RHFAD128V2 through the SPI protocol at 125 ksps.
The RHFAD128_GUI allows the user to monitor each channel and plot data on a graph. It is also a tool to save
values measured by the RHFAD128 in a .csv file.
For more information on the RHFAD128_GUI GUI, go to the relevant STMicroelectronics web page.
Figure 5. RHFAD128_GUI: GUI for RHFAD128
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Communication with the RHFAD128
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3.2 Option B: use the EVAL-RHFAD128V2 directly with your test solution
The EVAL-RHFAD128V2 can be plugged directly to your solution.
The SPI communication to access the RHFAD128 registers giving access to the measured values of each
channel is shown in the following tables.
Table 2. Control register bits
Bit # 7 (MSB) 6 5 4 3 2 1 0
Symbol DONTC DONTC ADD2 ADD1 ADD0 DONTC DONTC DONTC
Table 3. Control register bit description
Bit # Symbol Description
7, 6, 2, 1, 0 DONTC Don't care
5 ADD2
These bits determine which input channel is converted, as per4 ADD1
3 ADD0
Table 4. Input channel description
ADD2 ADD1 ADD0 Address value (h) Input channel
0 0 0 00 IN0
0 0 1 08 IN1
0 1 0 10 IN2
0 1 1 18 IN3
1 0 0 20 IN4
1 0 1 28 IN5
1 1 0 30 IN6
1 1 1 38 IN7
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Option B: use the EVAL-RHFAD128V2 directly with your test solution
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4The use of RHF43B and RHF100
4.1 1.2 V reference voltage on channel 0
The RHF100 is not mounted on board.
The RHF100 reference voltage can be measured on the channel IN0.
By default, the R42 value can be 0 Ω. However, R42 = 200 Ω and C42 = 10 nF can be a good combination for
low-pass filter at FCLK = 500 KHz.
The measured output voltage is 1.2 V.
Figure 6. Reference voltage
4.2 Current sensing
The RHF43B is not mounted on board.
The RHF43B op amp can be used for current sensing or for voltage amplification. It is connected to the
RHFAD128 input channel 5 (IN5).
The op amp output voltage Vout must be within the range [0 V, AVCC].
By default, the R27 value can be 0 Ω. However, R27 = 200 Ω and C23=10 nF can be a good combination for
low-pass filter at FCLK = 500 KHz.
Figure 7 is an extract of the power supply management schematic.
There are different ways to power the op amp and to measure the current or the voltage:
1. Power supply @ 5 V
• The reference voltage RHF100 * is powered by Vcc = 5 V
• Vcc+ = 5 V → J33 = 5 V → J35 jumper upper side connected
• Vcc- = GND → J37 jumper lower side connected
• REF floating → J38 not connected → R28, R29, R30 not connected
2. Power supply @ custom Vcc- / Vcc+
• Vcc+ = V+ → J34 = custom → J35 jumper lower side connected
• Vcc- = V- → J34 = custom → J37 jumper upper side connected
• REF custom → J38 = custom → R28, R29 connected
• In practice, REF = AVCC
• R28 = R29 = 2 * R26
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The use of RHF43B and RHF100
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Figure 7. RHF100 and RHF43B power supply setup
Figure 8 is an extract of the board schematic. It shows the different modes to measure the amplifier output
voltage.
4.2.1 Mode 1: Low-side current sensing
An external load could be connected to the connector J22. The current through this load is measured by the
following setup:
• J21 = +5 V if the external load is powered by 5 V
• J21 = is open if the external load is powered by external supply
• J22 = LOAD
• J23 = GND
• J24 = REX
• R25 = R23
• R26 = R24
The RHF43B gain is:
• G = R26 / R25
The measured current through the shunt resistance R21 is:
Case 1: REF voltage is not used:
• R24 = R26
• Vout = I * R21 * Gain
• I = Vout / (Gain * R21)
Case 2: REF voltage is used:
• R24 is not connected
• Vout = REF / 2 + I * R21 * Gain
• I = (Vout - REF/2) / (Gain * R21)
4.2.2 Mode 2: High-side current sensing
The setup is the following:
• J21 = GND
• J22 = LOAD
• J23 = REX
• J24 = +5 V if the external load is powered by 5 V
• J24 = is open if the external load is powered by external supply
• R25 = R23
The RHF43B gain is:
• G = R26 / R25
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Current sensing
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The measured current through the shunt resistance R21 is:
Case 1: REF voltage is not used:
• R24 = R26
• Vout = I * R21 * Gain
• I = Vout / (Gain * R21)
Case 2: REF voltage is used:
• R24 is not connected
• Vout = REF/2 + I * R21 * Gain
• I = (Vout - REF/2) / (Gain * R21)
4.2.3 Mode 3: Custom input voltage
The setup is:
• J21 = GND
• J22 = External VIN
• J23 = REX
• J24 = No use
• R21 = Not connected
• R25 = R23
• R26 = R24
• Gain = R26/R25
• Vout = REF/2 + VIN * Gain
Figure 8. RHF43B current sensing
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Current sensing
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5EVAL-RHFAD128V2 versions
Table 5. EVAL-RHFAD128V2 versions
PCB version Schematic diagrams Bill of materials
EVAL-RHFAD128V2 (1) EVAL-RHFAD128V2 schematic diagrams EVAL-RHFAD128V2 bill of materials
1. This code identifies the EVAL-RHFAD128V2 expansion board first version. It is printed on the board PCB.
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EVAL-RHFAD128V2 versions
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6Schematic diagrams
Figure 9. EVAL-RHFAD128V2 board schematic
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Schematic diagrams

Figure 10. EVAL-RHFAD128V2 board PCB top layer
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Schematic diagrams

Figure 11. EVAL-RHFAD128V2 board PCB bottom layer
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Schematic diagrams

Figure 12. EVAL-RHFAD128V2 board PCB top overlay
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Schematic diagrams

7Bill of materials
Table 6. EVAL-RHFAD128V2 bill of materials
Item Quant
ity Reference Value Package Description Voltage Manufacturer Manufacturer’s part number
1 6
C01, C03,
C31, C32,
C33, C34
1µF SMT 0805 CAPACITOR -
CERAMIC 25V WURTH ELEKTRONIK 885012207078
2 8
C02, C04,
C11, C12,
C13, C14,
C15, C16
10nF SMT 0603 CAPACITOR -
CERAMIC 50V WURTH ELEKTRONIK 885012206089
3 2 C21, C41 100nF SMT 0603 CAPACITOR -
CERAMIC 50V WURTH ELEKTRONIK 885012206095
3C22, C23,
C42 TBD SMT 0603 CAPACITOR - CERAMIC 50V
5 1 D01 COLOR
GREEN SMT 0603 LED 2V WURTH ELEKTRONIK 150060VS55040
6 1 D02 COLOR
RED SMT 0603 LED 2V WURTH ELEKTRONIC 150060RS55040
7 1 J01 COLOR
GREY
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 2100V JOHNSON - CINCH CONNECTIVITY 105-0763-001
8 4 J02, J05,
J32, J39
COLOR
BLACK
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 1500V JOHNSON - CINCH CONNECTIVITY 105-0753-001
9 4 J03, J06,
J33, J40
SIP 1X2
MALE
SIP 2 STEP
2.54MM PIN HEADER 250VAC WURTH ELEKTRONIK 61300211121
10 2 J04, J34 COLOR
RED
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 2100V JOHNSON - CINCH CONNECTIVITY 105-0752-001
11 1 J11 SIP 2X6
MALE
SIP 2X6
STEP
2.54MM
CONNECTOR
- HEADER 250VAC WURTH ELEKTRONIK 61301221121
12 3 J21, J35, J37 SIP 1X3
MALE
SIP 2 STEP
2.54MM
CONNECTOR
- HEADER 250VAC WURTH ELEKTRONIK 61300311121
13 1 J22 SIP 1X2
MALE
BORNIER
1X2 STEP
7.62MM
CONNECTOR
- TERMINAL
BLOCK
1.6KV WURTH ELEKTRONIC 691218410002
14 2 J23, J24 SIP 2X4
MALE
SIP 2X4
STEP
2.54MM
CONNECTOR
- HEADER 250VAC WURTH ELEKTRONIK 61300421121
15 1 J31 COLOR
YELLOW
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 2100V JOHNSON - CINCH CONNECTIVITY 105-0757-001
16 1 J36 COLOR
BLUE
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 2100V JOHNSON - CINCH CONNECTIVITY 105-0760-001
17 1 J38 COLOR
GREEN
HORIZONTA
L TEST
JACK 2MM
TEST JACK
2MM 2100V JOHNSON - CINCH CONNECTIVITY 105-0754-001
18 1 J50 SIP 1X5
MALE
SIP 5 STEP
2.54MM PIN HEADER 250VAC WURTH ELEKTRONIK 61300511121
19 1 JU21 WHITE
COLOR
STEP
2.54MM JUMPER 250VAC Harwin M7684-46
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Bill of materials
UM3160 - Rev 1 page 16/23

Item Quant
ity Reference Value Package Description Voltage Manufacturer Manufacturer’s part number
20 1 JU23 BLACK
COLOR
STEP
2.54MM JUMPER 250VAC WURTH ELEKTRONIK 609002115121
21 1 JU24 YELLOW
COLOR
STEP
2.54MM JUMPER 650VAC RS 251-8525
22 1 JU35 RED
COLOR
STEP
2.54MM JUMPER 250VAC Harwin M7681-05
23 1 JU37 BLUE
COLOR
STEP
2.54MM JUMPER 250VAC Harwin M7683-05
24 4 M-01, M-02,
M-03, M-04 10MM HOLE M2 THREADED SPACER WURTH ELEKTRONIK 970100244
25 4 M-05, M-06,
M-07, M-08 6MM HOLE M3 SCREW MULTICOMP PRO MP006574
26 2 PT21, PT41 RED
COLOR
HOLE
1.6MM TEST POINT KEYSTONE 5010
27 4 PT51, PT52,
PT53, PT54
WHITE
COLOR
HOLE
1.6MM TEST POINT KEYSTONE 5012
28 1 PT55 BLACK
COLOR
HOLE
1.6MM TEST POINT KEYSTONE 5011
29 2 R01, R02 2K2 SMT 0603 RESISTOR PANASONIC ERJPA3F2201V
30 1 R03 49.9 SMT 0603 RESISTOR PANASONIC ERJPA3F49R9V
31 6
R11, R12,
R13, R14,
R15, R16
200 SMT 0603 RESISTOR PANASONIC ERJPA3F2000V
32 7
R21, R23,
R24, R25,
R26, R27,
R42
TBD SMT 1206,
SMT 0603 RESISTOR
33 3 R28, R29,
R30 TBD SMT 0603 RESISTOR
34 1 R41 10K SMT 0603 RESISTOR PANASONIC ERJPA3F1002V
35 4 R51, R52,
R53, R54 33 SMT 0603 RESISTOR PANASONIC ERJPA3F33R0V
36 1 U01 RHFAD12
8Flat-16
8
MULTIPLEXED
CHANNEL -
500Ksps TO
1Msps - 12-BIT
ADC
2.7V TO
5.5V STMicroelectronics RHFAD128
37 0 U21 RHF43B Flat-8
IC - Rad-hard
precision
bipolar single
operational
amplifier
3V TO
16V STMicroelectronics RHF43BK1
38 0 U41 RHF100 Flat-10
Rad-hard,
1.2V, precision
shunt, voltage
reference
Vk =
1.2V STMicroelectronics RHF100K1
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Bill of materials
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8Regulatory compliance information
Notice for US Federal Communication Commission (FCC)
For evaluation only, not FCC approved for resale FCC NOTICE - This kit is designed to allow:
Product developers to evaluate electronic components, circuitry, or software associated with the kit to determine
whether to incorporate such items in a finished product and software developers to write software applications for
use with the end product.
This kit is not a finished product and when assembled may not be resold or otherwise marketed unless all
required FCC equipment authorizations are first obtained. Operation is subject to the condition that this product
does not cause harmful interference to licensed radio stations and that this product accepts harmful interference.
Unless the assembled kit is designed to operate under part 15, part 18, or part 95 of this chapter, the operator of
the kit must operate under the authority of an FCC license holder or must secure an experimental authorization
under part 5 of this chapter 3.1.2.
Notice for Innovation, Science and Economic Development Canada (ISED)
For evaluation purposes only. This kit generates, uses, and can radiate radio frequency energy and has not been
tested for compliance with the limits of computing devices pursuant to Industry Canada (IC) rules.
À des fins d'évaluation uniquement. Ce kit génère, utilise et peut émettre de l'énergie radiofréquence et n'a pas
été testé pour sa conformité aux limites des appareils informatiques conformément aux règles d'Industrie Canada
(IC).
Notice for the European Union
This device is in conformity with the essential requirements of the Directive 2014/30/EU (EMC) and of the
Directive 2015/863/EU (RoHS).
Notice for the United Kingdom
This device is in compliance with the UK Electromagnetic Compatibility Regulations 2016 (UK S.I. 2016 No. 1091)
and with the Restriction of the Use of Certain Hazardous Substances in Electrical and Electronic Equipment
Regulations 2012 (UK S.I. 2012 No. 3032).
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Regulatory compliance information
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Revision history
Table 7. Document revision history
Date Version Changes
24-May-2023 1 Initial release.
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Contents
1Getting started ....................................................................2
1.1 Features ......................................................................2
1.2 Main components ..............................................................2
1.2.1 RHFAD128 .............................................................2
1.2.2 RHF100 ...............................................................2
1.2.3 RHF43B ...............................................................3
2How to use the board ..............................................................4
3Communication with the RHFAD128................................................6
3.1 Option A: use the STSW-AKI GUI.................................................6
3.2 Option B: use the EVAL-RHFAD128V2 directly with your test solution ..................7
4The use of RHF43B and RHF100 ...................................................8
4.1 1.2 V reference voltage on channel 0 ..............................................8
4.2 Current sensing ................................................................8
4.2.1 Mode 1: Low-side current sensing............................................9
4.2.2 Mode 2: High-side current sensing ...........................................9
4.2.3 Mode 3: Custom input voltage..............................................10
5EVAL-RHFAD128V2 versions......................................................11
6Schematic diagrams ..............................................................12
7Bill of materials...................................................................16
8Regulatory compliance information ...............................................18
Revision history .......................................................................19
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Contents
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