Texas Instruments TPS7A91EVM-831 User manual

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TPS7A91EVM-831 Evaluation Module
User's Guide
SBVU036–November 2016
TPS7A91EVM-831 Evaluation Module
This user’s guide describes the operational use of the TPS7A91EVM-831 evaluation module (EVM) as a
reference design for engineering demonstration and evaluation of the TPS7A9101DSK, low-dropout linear
regulator (LDO). Included in this user’s guide are setup and operating instructions, thermal and layout
guidelines, a printed-circuit-board (PCB) layout, a schematic diagram, and a bill of materials (BOM).
Throughout this document, the terms demonstration kit, evaluation board, evaluation module are
synonymous with the TPS7A91EVM-831.
The following related documents are available through the Texas Instruments web site at
http://www.ti.com.
Related Documentation
Device Literature Number
TPS7A91 SBVS282

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Contents
1 Introduction ................................................................................................................... 3
1.1 Before You Begin................................................................................................... 3
2 EVM Setup.................................................................................................................... 4
2.1 Input/Output Connectors and Jumper Descriptions............................................................ 4
2.2 Soldering Guidelines ............................................................................................... 6
2.3 Equipment Connection............................................................................................. 6
3 Operation ..................................................................................................................... 6
4 PCB Layout................................................................................................................... 7
5 Schematic..................................................................................................................... 9
6 Bill of Materials ............................................................................................................. 10
List of Figures
1 Assembly Layer.............................................................................................................. 7
2 Top Layer Routing........................................................................................................... 7
3 Bottom Layer Routing....................................................................................................... 8
4 Schematic..................................................................................................................... 9
List of Tables
1 Bill of Materials ............................................................................................................. 10
Trademarks
All trademarks are the property of their respective owners.

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1 Introduction
The Texas Instruments TPS7A91EVM-831 EVM helps design engineers evaluate the operation and
performance of the TPS7A91 family of linear regulators for possible use in their own circuit application.
This particular EVM configuration contains a dual low-noise, high-PSRR linear regulator for high-speed
communication systems. The regulator is capable of delivering up to 1 A to the load with low VIN to VOUT
dropout voltage. For stability, use a 10-µF input capacitor and 10-µF output capacitor for the TPS7A91.
1.1 Before You Begin
The following warnings and cautions are noted for the safety of anyone using or working close to the
TPS7A91EVM-831. Observe all safety precautions.
WARNING
Hot surface. Contact may cause burns. Do not touch.
CAUTION
The circuit module may be damaged by overtemperature. To avoid damage,
monitor the temperature during evaluation and provide cooling, as needed, for
your system environment.
CAUTION
Some power supplies can be damaged by application of external voltages. If
using more than one power supply, check your equipment requirements and
use blocking diodes or other isolation techniques, as needed, to prevent
damage to your equipment.
CAUTION
The circuit module is not a finished product or electrical appliance. The module
does not contain current or voltage thresholds for circuit protection. It must be
used by qualified personnel with additional equipment for evaluation only.

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2 EVM Setup
This section describes how to properly connect and setup the TPS7A91EVM-831, including the jumpers
and connectors on the EVM board.
2.1 Input/Output Connectors and Jumper Descriptions
2.1.1 J1 – VIN_S
Input power-supply sense voltage connector. Place an SMA connector here to sense the input supply
voltage.
2.1.2 J2 – VPG
Pullup voltage selector for PG. This EVM is designed so that PG can be pulled up to either VOUT by
shorting J2, or pulled up to another voltage by applying an external voltage to the VPG post.
2.1.3 J3 – VOUT_S
Output power-supply sense voltage connector. Place an SMA connector here to sense the output voltage.
2.1.4 J4 – VIN
Input power-supply voltage connector. Twist together the positive input lead and ground return lead from
the input power supply; keep the leads as short as possible to minimize input inductance. Add additional
bulk capacitance between J4 and J7 (use the C2 or C1 footprint) if the supply leads are longer than six
inches.
2.1.5 J5 – VOUT
Regulated output voltage connector.
2.1.6 J6 – EN
Output enable. To enable the output, connect a jumper to short VIN to EN. To disable the output, connect
a jumper to short EN to GND.
2.1.7 J7 – GND
Return connector for the input power supply.
2.1.8 J8 – GND
Output ground return connector.
2.1.9 J9 – SS_CTRL
Soft-start control. Connect a jumper to short VIN1 to SS_CTRL for a fast charge time. Connect a jumper
to short SS_CTRL to GND for a slower startup.
2.1.10 J10 – ANYOUT
The output voltage of the TPS7A91 is selectable in accordance with the names given to the output voltage
setting pins: 50 mV, 100 mV, 200 mV, 400 mV, 800 mV, 1.6 V, and 1.6 V. For each pin connected to the
ground, the output voltage setting increases by the value associated with that pin name, starting from the
value of the reference voltage of 0.8 V; floating the pins has no effect on the output voltage.
2.1.11 TP1 – VI_S
Input sense test point.

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2.1.12 TP2 – VO_S
Output sense test point.
2.1.13 TP3 – EN
Enable test point.
2.1.14 TP4 – PG
Power-Good test point.
2.1.15 TP5 – INJECT
Injection signal test point. To take open loop measurements, remove resistor R2 and inject a small signal
at TP5.
2.1.16 TP6 – FB
Feedback sense test point.
2.1.17 TP7 – GND
Ground.
2.1.18 TP8 – GND
Ground.
2.1.19 TP9 – GND
Ground.
2.1.20 TP10 – GND
Ground.

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2.2 Soldering Guidelines
To avoid damaging the integrated circuit (IC), use a hot-air system for any solder rework to modify the
EVM for the purpose of repair or other application reasons.
2.3 Equipment Connection
1. Set the input power supply to 6.5 V (max), and turn the power supplies off.
2. Connect the positive voltage lead from input power supply to VIN at the J4 connector of the EVM.
3. Connect the ground lead from input power supply to GND at the J7 connector of the EVM.
4. Connect a 0-A to 1-A load between OUT and GND.
5. Disable the output by shorting EN to GND on J6.
3 Operation
1. Turn on the power supply.
2. Enable the output by shorting the EN pin to VIN on J6.
3. Vary the load and input voltage as necessary for test purposes.

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4 PCB Layout
Figure 1 to Figure 3 illustrate the PCB layout for this EVM.
Figure 1. Assembly Layer
Figure 2. Top Layer Routing

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Figure 3. Bottom Layer Routing

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5 Schematic
Figure 4 is the schematic for this EVM.
Figure 4. Schematic

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6 Bill of Materials
The bill of materials (BOM) for this EVM is shown in Table 1
(1) These assemblies must comply with workmanship standards IPC-A-610 Class 2.
(2) Unless otherwise noted in the Alternate PartNumber and/or Alternate Manufacturer columns, all parts may be substituted with equivalents.
Table 1. Bill of Materials(1)(2)
Designator Qty Value Description Package Reference Part Number Manufacturer Alternate Part
Number Alternate Manufacturer
!PCB 1 Printed Circuit Board PWR831 Any - -
C3, C4 2 10uF CAP, CERM, 10 µF, 16 V, +/- 20%, X5R, 0603 0603 GRM188R61C106MAALD Murata
C7 1 0.01uF CAP, CERM, 0.01 µF, 16 V, +/- 10%, X7R,
0603 0603 GRM188R71C103KA01D Murata
C8 1 0.1uF CAP, CERM, 0.1 µF, 16 V, +/- 10%, X7R, 0603 0603 CL10B104KO8NNNC Samsung Electro-
Mechanics
J2 1 Header, 2.54 mm, 2x1, Gold, R/A, SMT Header, 2.54 mm, 2x1, R/A,
SMT 87898-0204 Molex
J4, J5 2 Standard Banana Jack, Insulated, Red 6091 6091 Keystone
J6, J9 2 Header, 100mil, 3x1, Gold, SMT Samtec_TSM-103-01-X-SV TSM-103-01-L-SV Samtec
J7, J8 2 Standard Banana Jack, Insulated, Black 6092 6092 Keystone
J10 1 Header, 100mil, 7x2, SMT Header, 100 mil, 7x2, SMT 0015912140 Molex
R1 1 10k RES, 10 k, 5%, 0.1 W, 0603 0603 CRCW060310K0JNEA Vishay-Dale
R2 1 0 RES, 0, 5%, 0.1 W, 0603 0603 CRCW06030000Z0EA Vishay-Dale
R3, R6 2 12.1k RES, 12.1 k, 1%, 0.1 W, 0603 0603 CRCW060312K1FKEA Vishay-Dale
R4, R5 2 6.04k RES, 6.04 k, 1%, 0.1 W, 0603 0603 CRCW06036K04FKEA Vishay-Dale
R7 1 24.3k RES, 24.3 k, 1%, 0.1 W, 0603 0603 CRCW060324K3FKEA Vishay-Dale
R8 1 48.7k RES, 48.7 k, 1%, 0.1 W, 0603 0603 CRCW060348K7FKEA Vishay-Dale
R9 1 97.6k RES, 97.6 k, 1%, 0.1 W, 0603 0603 CRCW060397K6FKEA Vishay-Dale
R10 1 196k RES, 196 k, 1%, 0.1 W, 0603 0603 CRCW0603196KFKEA Vishay-Dale
SH-J1, SH-J2, SH-J3,
SH-J4, SH-J5 5 1x2 Shunt, 100mil, Gold plated, Black Shunt 969102-0000-DA 3M SNT-100-BK-G Samtec
TP1, TP2, TP3, TP4,
TP7, TP8, TP9, TP10 8 Test Point, Compact, SMT Testpoint_Keystone_Compact 5016 Keystone
U1 1 High-Accuracy (1%),Low-Noise (3.8-uVRMS), 1-
A LDO Voltage Regulator, DSK0010A DSK0010A TPS7A9101DSKR Texas Instruments TPS7A9101DSKT Texas Instruments
C1, C2, C5, C6 0 10uF CAP, CERM, 10 µF, 16 V, +/- 20%, X7R, 0805 0805 EMK212BB7106MG-T Taiyo Yuden
FID1, FID2, FID3 0 Fiducial mark. There is nothing to buy or mount. Fiducial N/A N/A
J1, J3 0 Connector, SMA Jack, Vertical, Gold, SMD SMA 142-0711-201 Emerson Network
Power
TP5, TP6 0 Test Point, Compact, SMT Testpoint_Keystone_Compact 5016 Keystone