Texas Instruments TCA8424 User manual

User's Guide
SCDU004–March 2013
TCA8424 Evaluation Module
This document is the EVM user guide for the TCA8424. The device is a low-voltage keyboard scanner that
can support up to 128 keys, with open drain outputs that can sink up to 12 mA of current for LEDs. The
TCA8424 is fully HID over I2C™ compliant and is available with a pre-programmed keyboard map.
Contents
1 About this Manual ........................................................................................................... 2
2 Information about Cautions and Warnings .............................................................................. 2
3 FCC Warning ................................................................................................................ 2
4 Items Required for Operation ............................................................................................. 3
5 Introduction .................................................................................................................. 3
6 TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions .................................. 4
6.1 TCA8424 EVM Schematic ........................................................................................ 4
6.2 Printed-Circuit Board (PCB) Layout ............................................................................. 5
6.3 Bill of Materials ..................................................................................................... 9
6.4 VCC and GND Connections .................................................................................... 11
6.5 MSP430 Launchpad Interface .................................................................................. 11
6.6 Breakout Pins ..................................................................................................... 12
6.7 LED Outputs ...................................................................................................... 13
7 Launchpad Software Setup .............................................................................................. 14
8 GUI Software Setup ....................................................................................................... 16
9 GUI Walkthrough Guide .................................................................................................. 17
10 Related Documentation ................................................................................................... 30
List of Figures
1 TCA8424 EVM Schematic................................................................................................. 4
2 Layer 1 Top Side: 50-ΩSignal Layer .................................................................................... 5
3 Layer 2 (Int1): Ground Plane.............................................................................................. 6
4 Layer 3 (Int2): 50-ΩSignal with Ground Fill............................................................................. 7
5 Layer 4 Bottom Layer ...................................................................................................... 8
6 VCC and GND Connections ............................................................................................. 11
7 MSP430 Launchpad Interface ........................................................................................... 11
8 Breakout Pins .............................................................................................................. 12
9 LED Outputs ............................................................................................................... 13
List of Tables
1 Bill of Materials.............................................................................................................. 9
2 Header Configurations for P1, P2, and P7............................................................................. 12
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1 About this Manual
This user’s guide describes the TCA8424 Evaluation Module (EVM). This guide contains the EVM
schematics, bill of materials, and top and bottom board layouts.
2 Information about Cautions and Warnings
This section describes the jumpers and connectors on the EVM as well and how to properly connect, set
up, and use the TPS22985EVM.
CAUTION
This EVM contains components that can potentially be damaged by
electrostatic discharge. Always transport and store the EVM in its supplied ESD
bag, when not in use. Handle using an antistatic wristband. Operate on an
antistatic work surface. For more information on proper handling, see the
Electrostatic Discharge (ESD) application note (SSYA008).
The information in a caution or a warning is provided for your protection. Please read each caution and
warning carefully.
3 FCC Warning
This equipment is intended for use in a laboratory test environment only. It generates, uses, and can
radiate radio frequency energy and has not been tested for compliance with the limits of computing
devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable
protection against radio frequency communications, in which case the user, at their own expense is
required to take whatever measures necessary to correct this interference.
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www.ti.com Items Required for Operation
4 Items Required for Operation
The following items are required to program a TCA8424:
• TCA8424 EVM with un-programmed TCA8424 in socket
• Single 3.3-V supply
• MSP-EXP430G2 Rev 1.5 Launchpad with MSP430G2553 installed
• USB to mini-USB cable
• PC with Code Composer Studio installed running supplied firmware
• PC with Application GUI installed
The following items are required to evaluate at the system level:
• TCA8424 EVM with programmed TCA8424 in socket
• Breakout wires to connect to keyboard matrix rows and columns
• Keyboard matrix
• Host system with I2C plus INT connected to board
5 Introduction
The benefits of the TCA8424 over other microcontroller-based solutions are lower development costs,
smaller package, and lower power consumption. The lower development costs are seen due to the
TCA8424 requiring programming of only 512 Bytes of OTP versus a full code stack on a microcontroller.
The TCA8424 is fully compliant with HID over I2C based systems with little to no host firmware
development.
The TCA8424 can also be used in a non-Hid over I2C environment by developing host drivers that mimic
the HID over I2C protocol to interpret the input reports. The EVM features a socket to allow easy
programming of multiple units for testing. The code stack supplied with the EVM is designed to interface
with the MSP430G2553 Launchpad to accomplish this. Once programmed, the EVM features breakout
headers for the keyboard and I2C connections to test in customer systems.
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6 TCA8424 EVM Design Circuitry, Bill of Materials, and Connection Descriptions
6.1 TCA8424 EVM Schematic
Figure 1 shows the schematic for the EVM. The connections on the EVM are briefly explained in the
subsequent sections.
Figure 1. TCA8424 EVM Schematic
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6.2 Printed-Circuit Board (PCB) Layout
Figure 2 to Figure 5 show the PCB layouts for the TCA8424 EVM.
Figure 2. Layer 1 Top Side: 50-ΩSignal Layer
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Figure 3. Layer 2 (Int1): Ground Plane
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Figure 4. Layer 3 (Int2): 50-ΩSignal with Ground Fill
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Figure 5. Layer 4 Bottom Layer
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6.3 Bill of Materials
Table 1 is the bill of materials for this EVM.
Table 1. Bill of Materials
ITEM QTY MFG MFG PART# REF DES DESCRIPTION
1 4 PANASONIC LNJ308G8PRA LED1, LED2, LED3, LED4 LED,SMT,0603,PURE GREEN,2.03V
2 1 POMONA ELECTRONICS 2269-0 J1 DUAL INSULATED BANANA JACKS,
BLACK, 0.75LS
3 1 PANASONIC ECJ-1V41E105M C4, C5, C6, C7, C8, C9, C10, C11, CAPACITOR,SMT,0603,CERAMIC,1.0u
F,25V,20%,X5S
4 1 PANASONIC ECJ-1VB0J106M C12 CAPACITOR,SMT,0603,CERAMIC,10u
F,6.3V,20%,X5R
5 1 TAIYO YUDEN TMK107SD472JA C2 CAPACITOR,SMT,0603,CERAMIC,470
0pF,25V,5%,SD
6 1 VISHAY SPRAGUE 594D687X0010R2T C3 CAP,TAN,SMT,10V,20%, 680uF
7 1 PANASONIC EEFUD0K101R C1 CAP,SMT,ELE,100uf,8V,20%
8 1 DIODES INC B230-13-F CR2 DIODE,SCHOTTKY,SMT, DIODES,INC.
9 1 DIODES INC SD103CW-13-F CR1 SCHOTTKEY
DIODE,SMT,20V,400mW,SOD-123
10 1 SAMTEC TSW-104-07-G-D P2 HEADER,THU,8P,2X4,MALE,DUAL
ROW,100LS,100TL
11 1 SAMTEC TSW-108-07-G-D P1 HEADER,THU,16P,2X8,MALE,DUAL
ROW,100LS,100TL
12 2 FCI 66951-010LF P8, P9 HEADER,THU,10P,1X10,FEMALE,SIN
GLE ROW,100LS,200TL
13 6 SAMTEC TSW-101-07-G-S P3, P4, P5, P6, P10, P11 HEADER,THU,1P,MALE,SINGLE
ROW,100TL
14 5 TE Connectivity 9-146281-0-02 P12, P13, P14, P15, P16
15 1 TE Connectivity 9-146281-0-04 P17
16 1 *ENPLAS CORPORATION QFN-40B-0.5-01 DUT3 HTSOCKET,QFN,40P,35x29x16.7mm,
w 2.1hole
17 1 TI TPS77001DBV U2 1.2~5.5V,ULTRA LOW-POWER 50mA
LOW-DROP LINE REGULATOR
18 1 TI TPS27081ADDCR U3 HIGH SIDE LOAD SWITCH WITH LVL
SHFT AND ADJ SLEW RATE
19 1 TI LM2700MTX-ADJ/NOPB U4 LM2700 600KHZ/1.25MHZ,2.5A,
STEPUP PWM DC/DC CONVERTER
20 1 BOURNS SDR0805-100ML L1 INDUCTOR,SMT,2P,POWER,10uH,20
%,RoHS
21 1 VISHAY CRCW060310K0FKEA R21 RESISTOR,SMT,0603,1%,1/10W,10.0K
22 3 VISHAY CRCW0603100KFKEA R10, R11, R12 RESISTOR,SMT,0603,1%,1/10W,100K
23 1 VISHAY CRCW06031K02FKEA R3 RESISTOR,SMT,0603,1%,1/10W,1.02K
24 1 VISHAY CRCW0603150KFKEA R9 RESISTOR,SMT,0603,1%,1/10W,150K
25 1 VISHAY CRCW0603169KFKEA R8 RESISTOR,SMT,0603,1%,1/10W,169K
26 1 VISHAY CRCW060320K0FKEA R15 RESISTOR,SMT,0603,1%,1/10W,20.0K
27 1 VISHAY CRCW06034K64FKEA R2 RESISTOR,SMT,0603,1%,1/10W,4.64K
28 4 PANASONIC ERJ-3GSYJ121 R4, R5, R6, R7 RESISTOR,SMT,0603,5%,1/10W,120
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Table 1. Bill of Materials (continued)
29 5 PANASONIC ERJ-3GSYJ122 R16, R17, R18, R19, R20 RESISTOR,SMT,0603,5%,1/10W,1.2K
30 0 BOURNS 3313J-1-204 R14 PlaceHolder, DO NOT INSTALL
32 0 PANASONIC ECJ-1V41E105M C13 PlaceHolder, DO NOT INSTALL
33 1 Texas Instruments TCA8424RHAR U1 TI device to be used in Socket
34 5 TE Connectivity 382811-8 N/A Jumpers to be installed over P12, P13,
P14, P15, P16
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