Texas Instruments REF35 User manual
User's Guide
REF35 Evaluation Module
ABSTRACT
The REF35 Evaluation Module (EVM) is an ultra low-power precision voltage reference evaluation module that
demonstrates the REF35 integrated circuit from Texas Instruments.
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
4 Revision History......................................................................................................................................................................9
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.
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SNAU276A – JANUARY 2022 – REVISED NOVEMBER 2023
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REF35 Evaluation Module 1
Copyright © 2023 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 is operable from VREF + VDO to 6 V. The REF35 uses only 1.4 μA of current in active mode. This
device comes with an enable pin that allows the device to be set in shutdown mode. The REF35 consumes only
0.1 μA of current under the shutdown condition. REF35 is available 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 desired. The VIN header is connectable 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 can cause permanent damage to your
hardware.
Overview www.ti.com
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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 10 uF CAP, CERM, 10 uF, 16 V, ±
10%, X7R, 1206
1206 GRM31CR71C106KAC7L Murata Electronics
C2, C4, C5, C7 4 0.1 uF CAP, CERM, 0.1 uF, 100 V, ±
10%, X7R, 0805
0805 C0805C104K1RACTU KEMET
C6 1 1 uF CAP, CERM, 1 uF, 16 V, ±
10%, X7R, 0805
0805 C0805C105K4RACTU KEMET
C8 1 10 uF CAP, CERM, 10 uF, 50 V, ±
10%, X5R, AEC-Q200 Grade
1, 1206
1206 GRT31CR61H106KE01L Murata Electronics
J1 1 50 Ω SMA JACK 50 Ω 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 1 499 Ω 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
7 Test Point,Multipurpose, Red,
TH
Keystone
_5010
5010 Keystone
Technologies
TP8, TP9,TP10,
TP11
4 Test 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-Voltage
Ultralow-IQ Low-Dropout
Regulator,DRV0006A
(WSON-6)
WSON-6 TPS7B8150QDRVRQ1 Texas Instruments
Overview www.ti.com
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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
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REF35 Evaluation Module 5
Copyright © 2023 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). Set the Power Select jumpers to Lab. The REF35 consumes 1.4 uA of current during
normal operating and has a maximum 10 mA of output current for maintaining regulated voltage. During start-up,
the REF35 can momentarily consume ISC 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, an A 5-V (up to the LDO max voltage, 40 V) power supply
capable of 50 mA of current is required. Set the Power Select jumpers 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 loads are 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.
Note
Test points TP8, TP9, TP10, and TP11 are not soldered to the ground plane. The user can connect
TP8, TP9, TP10, and TP11 to an external source ground if desired. Additionally, SMA connector J1 is
not soldered to the ground plane.
The output voltage of the REF35125QDBVR is 1.25 V.
Shutdown mode: Move the jumper pin from EN to SHDN to place the part in shutdown mode. The REF35 is in
active mode if the jumper pin is either in EN or not present.
Quick Setup Guide www.ti.com
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4 Revision History
Changes from Revision * (January 2022) to Revision A (November 2023) Page
• Updated the numbering format for tables, figures, and cross-references throughout the document................. 1
• Added a note and information about output voltage and shutdown mode......................................................... 6
Revision History www.ti.com
10 REF35 Evaluation Module SNAU276A – JANUARY 2022 – REVISED NOVEMBER 2023
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Copyright © 2023 Texas Instruments Incorporated
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