Texas Instruments REF35EVM User manual

User’s Guide
REF35EVM User's Guide
ABSTRACT
The REF35EVM is an ultra low-power precision voltage reference evaluation module that demonstrates the
REF35 integrated circuit from Texas Instruments (TI).
Table of Contents
1 Overview..................................................................................................................................................................................2
1.1 REF35EVM Features......................................................................................................................................................... 2
1.2 REF35EVM Schematic...................................................................................................................................................... 3
1.3 REF35EVM Bill of Materials...............................................................................................................................................4
1.4 REF35EVM Board..............................................................................................................................................................5
2 Quick Setup Guide..................................................................................................................................................................6
2.1 Electrostatic Discharge Warning........................................................................................................................................ 6
2.2 Power Supply Setup and Functional Test.......................................................................................................................... 6
3 Layout...................................................................................................................................................................................... 7
List of Figures
Figure 1-1. REF35EVM Schematic..............................................................................................................................................3
Figure 1-2. REF35EVM Board Top.............................................................................................................................................. 5
Figure 1-3. REF35EVM Board Bottom........................................................................................................................................ 5
Figure 3-1. Top Layer...................................................................................................................................................................7
Figure 3-2. Bottom Layer............................................................................................................................................................. 8
Figure 3-3. Top Solder Mask........................................................................................................................................................9
List of Tables
Table 1-1. REF35EVM BOM........................................................................................................................................................4
Trademarks
All trademarks are the property of their respective owners.
www.ti.com Table of Contents
SNAU276 – JANUARY 2022
Submit Document Feedback
REF35EVM User's Guide 1
Copyright © 2022 Texas Instruments Incorporated

1 Overview
The REF35EVM is a voltage reference evaluation module that demonstrates the REF35 integrated circuit from
Texas Instruments (TI).
The REF35 is an ultra-low power voltage reference with maximum 10 ppm/C temperature drift. The REF35 is
used primarily as a voltage reference for low power data converters.
The REF35 can be operated from VREF + VDO to 6 V. The REF35 uses only 1.4 μA of current in active mode.
This device comes with a enable pin that allows the device to be set in shutdown mode. Under the shutdown
condition, the REF35 only consumes 0.1 μA of current. The REF35 is optimal for a wide range of applications
such as flow transmitters, blood glucose monitors, servo drive control modules, power quality analyzers, fault
indicators, oscilloscopes and process analytics.
The REF35EVM features a user selectable wide VIN input which uses a TPS7B8150 linear regulator, allowing
the user to widen the input range to 40 V if so desired.. The VIN header can be connected to an external power
supply to provide power. All of the REF35 input and output pins are accessible for external connection via test
headers.
1.1 REF35EVM Features
• Includes: REF35125QDBVR
• Footprints for resistors and capacitors
• Multiple outputs for voltage measurements
KEY PARAMETERS PARAMETER PARAMETER LIMITS
Supply Voltage (VREF): IN_VREF 0 V – 6 V
Supply Voltage (VLDO) IN_LDO 0 V to 40 V
Enable Pin EN 0 V to IN_VREF
Fixed Output Voltage: VREF 1.25 V (REF35125QDBVR)
Output Current: IOUT -5 mA to 10 mA
CAUTION
Applying voltages above the limitations given in this table may cause permanent damage to your
hardware.
Overview www.ti.com
2REF35EVM User's Guide SNAU276 – JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

1.2 REF35EVM Schematic
The schematic for the REF35EVM is illustrated in Figure 1-1.
Figure 1-1. REF35EVM Schematic
www.ti.com Overview
SNAU276 – JANUARY 2022
Submit Document Feedback
REF35EVM User's Guide 3
Copyright © 2022 Texas Instruments Incorporated

1.3 REF35EVM Bill of Materials
Table 1-1. REF35EVM BOM
DESIGNATOR QTY VALUE DESCRIPTION PACKAGE PART NUMBER MANUFACTURER
!PCB 1 Printed Circuit Board LP053
C1, C3 2 10uF CAP, CERM, 10 uF, 16 V,
+/-10%, X7R, 1206
1206 GRM31CR71C106KAC7L Murata Electronics
C2, C4, C5, C7 4 0.1uF CAP, CERM, 0.1 uF, 100V, +/-
10%, X7R, 0805
0805 C0805C104K1RACTU KEMET
C6 1 1uF CAP, CERM, 1 uF, 16 V, +/-
10%, X7R, 0805
0805 C0805C105K4RACTU KEMET
C8 1 10uF CAP, CERM, 10 uF, 50 V, +/-
10%, X5R, AEC-Q200 Grade
1, 1206
1206 GRT31CR61H106KE01L Murata Electronics
J1 1 50OHM SMA JACK 50 OHM EDGE
MNT, SMT
SMT 142-0711-821 Cinch Connectivity
Solutions Johnson
P1, P2, P3 3 100mil Header, 100mil, 2x1, Tin, TH TH PEC02SAAN Sullins Connector
Solutions
P4, P5, P6, P7 4 100mil Header, 100mil, 3x1, Tin, TH TH PEC03SAAN Sullins Connector
Solutions
R1 1 499OHM RES, 499, 1%, 0.125 W, AEC-
Q200 Grade 0,
0805
0805 CRCW0805499RFKEA Vishay Dale
R2 1 1k RES, 1.00 k, 1%, 0.125W,
AEC-Q200 Grade 0,
0805
0805 CRCW08051K00FKEA Vishay Dale
R3, R4 2 0 RES, 0, 5%, 0.333 W, AEC-
Q200 Grade 0,
0805
0805 CRCW08050000Z0EAHP Vishay Dale
R5 1 10M RES, 10.0 M, 1%, 0.125
W, 0805
0805 CRCW080510M0FKEA Vishay Dale
TP1, TP2, TP3,
TP4, TP5,TP6,
TP7
7Test Point,Multipurpose,Red,
TH
Keystone
_5010
5010 Keystone
Technologies
TP8, TP9,TP10,
TP11
4Test Point,Miniature,Green, TH Keystone
_5116
5116 Keystone
Technologies
U1 1 Ultra Low-Power, High-
Precision Voltage Reference,
SOT23-6
SOT23-6 REF35125QDBVR Texas Instruments
U2 1 150-mA High-VoltageUltralow-
IQ Low-Dropout
Regulator,DRV0006A
(WSON-6)
WSON-6 TPS7B8150QDRVRQ1 Texas Instruments
Overview www.ti.com
4REF35EVM User's Guide SNAU276 – JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

1.4 REF35EVM Board
The PCB layout for the REF35EVM is illustrated in Figure 1-2 and Figure 1-3.
Figure 1-2. REF35EVM Board Top
Figure 1-3. REF35EVM Board Bottom
www.ti.com Overview
SNAU276 – JANUARY 2022
Submit Document Feedback
REF35EVM User's Guide 5
Copyright © 2022 Texas Instruments Incorporated

2 Quick Setup Guide
This section describes the setup to quickly check the functionality of the REF35EVM.
2.1 Electrostatic Discharge Warning
Many of the components on the REF35EVM are susceptible to damage by electrostatic discharge (ESD).
Customers are advised to observe proper ESD handling precautions when unpacking and handling the EVM,
including the use of a grounded wrist strap at an approved ESD workstation.
CAUTION
Failure to observe ESD handling procedures may result in damage to EVM components.
2.2 Power Supply Setup and Functional Test
Normal operation:
If directly connecting the REF35 to the lab supply, a A 5-V power supply capable of 50 mA of current is required
(to handle load transients). The "Power Select" jumpers should be set to "Lab". The REF35 consumes 1.4 uA of
current during normal operationg and has a maximum 10 mA of output current for maintaining regulated voltage.
During start-up, the REF35 might consume ISC momentarily to charge the output capacitors.
Connect the positive power supply lead to the "VIN_REF" pin on the "REF Power" header pin on the left side of
the board. Connect the negative power supply lead to the "GND" pin on the "REF Power" header pin.
If powering the REF35 through the on-EVM LDO, a A 5-V (up to the LDO max voltage, 40 V) power supply
capable of 50 mA of current is required. The "Power Select" jumpers should be set to "LDO".
Connect the positive power supply lead to the "VIN_REF" pin on the "REF Power" header pin on the left side of
the board. Connect the negative power supply lead to the "GND" pin on the "REF Power" header pin.
This EVM features selectable loads, where the load can be pulled to GND or VCC.
Connect a voltmeter to the VREF pin on the right side of the board. Connect the negative voltmeter terminal to
"GND". An SMA cable can also be used to measure the same output.
The output voltage of the REF35125QDBVR will be 1.25V.
Shutdown mode: Move the jumper pin from EN to SHDN to place the part in shutdown mode. The REF35 will be
in active mode if the jumper pin is either in EN or not present.
Quick Setup Guide www.ti.com
6REF35EVM User's Guide SNAU276 – JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

3 Layout
Figure 3-1 and Figure 3-2 show the top and bottom layers, and Figure 3-3 shows the top solder mask of the
EVM.
Figure 3-1. Top Layer
www.ti.com Layout
SNAU276 – JANUARY 2022
Submit Document Feedback
REF35EVM User's Guide 7
Copyright © 2022 Texas Instruments Incorporated

Figure 3-2. Bottom Layer
Layout www.ti.com
8REF35EVM User's Guide SNAU276 – JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

Figure 3-3. Top Solder Mask
www.ti.com Layout
SNAU276 – JANUARY 2022
Submit Document Feedback
REF35EVM User's Guide 9
Copyright © 2022 Texas Instruments Incorporated

IMPORTANT NOTICE AND DISCLAIMER
TI PROVIDES TECHNICAL AND RELIABILITY DATA (INCLUDING DATA SHEETS), DESIGN RESOURCES (INCLUDING REFERENCE
DESIGNS), APPLICATION OR OTHER DESIGN ADVICE, WEB TOOLS, SAFETY INFORMATION, AND OTHER RESOURCES “AS IS”
AND WITH ALL FAULTS, AND DISCLAIMS ALL WARRANTIES, EXPRESS AND IMPLIED, INCLUDING WITHOUT LIMITATION ANY
IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT OF THIRD
PARTY INTELLECTUAL PROPERTY RIGHTS.
These resources are intended for skilled developers designing with TI products. You are solely responsible for (1) selecting the appropriate
TI products for your application, (2) designing, validating and testing your application, and (3) ensuring your application meets applicable
standards, and any other safety, security, regulatory or other requirements.
These resources are subject to change without notice. TI grants you permission to use these resources only for development of an
application that uses the TI products described in the resource. Other reproduction and display of these resources is prohibited. No license
is granted to any other TI intellectual property right or to any third party intellectual property right. TI disclaims responsibility for, and you
will fully indemnify TI and its representatives against, any claims, damages, costs, losses, and liabilities arising out of your use of these
resources.
TI’s products are provided subject to TI’s Terms of Sale or other applicable terms available either on ti.com or provided in conjunction with
such TI products. TI’s provision of these resources does not expand or otherwise alter TI’s applicable warranties or warranty disclaimers for
TI products.
TI objects to and rejects any additional or different terms you may have proposed. IMPORTANT NOTICE
Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265
Copyright © 2022, Texas Instruments Incorporated