Texas Instruments TLC5940 EVM User manual

1 Introduction
User's GuideSLVU139 – September 2005
TLC5940 EVM
This user’s guide describes the characteristics, operation, and use of theTLC5940EVM-106 evaluation module (EVM). This EVM is designed to help the userevaluate and test the various operating modes of the TLC5940. This user’s guideincludes setup instructions for the hardware and software, a schematic diagram, a billof materials (BOM), and PCB layout drawings for the evaluation module
Contents1 Introduction .......................................................................................... 12 Board Layout ........................................................................................ 73 Related Documentation From Texas Instruments ............................................ 134 Bill of Materials and Schematic ................................................................. 13
List of Figures
1 Hardware Setup ..................................................................................... 32 Assembly Layer ..................................................................................... 83 Top Layer Routing .................................................................................. 94 Layer 2 Routing ................................................................................... 105 Layer 3 Routing ................................................................................... 116 Bottom Layer Routing ............................................................................ 127 TLC5940EVM-106 Schematic ................................................................... 158 TLC5940EVM-106 Schematic (Continued) .................................................... 16
List of Tables
1 J1 – Interface Connector .......................................................................... 42 J2 – Power Connector ............................................................................. 43 EVM Power Requirements ........................................................................ 44 J3 – Power Connector ............................................................................. 55 Data Input Mode Jumper Configurations ........................................................ 66 Data Input Mode Jumper Configurations ........................................................ 77 Bill of Materials .................................................................................... 13
The Texas Instruments TLC5940 is a 16 channel constant current LED driver that is capable of driving120 mA per channel. The IC contains an integrated DOT correction circuitry that adjusts the dc current foreach output channel to compensate for brightness difference between LEDs. DOT correction informationcan be written into a non-volatile EEPROM or into internal registers. It also has integrated PWM grayscalecontrol to provide individual LED dimming.
This EVM contains three TLC5940 ICs that are connected in series. The three TLC5940 ICs drive 16red-green-blue light emitting diodes (RGB LEDs). Each TLC5940 drives a separate color. Each TLC5940has 16 outputs and each output is connected to a different LED. Using the software, the user individuallycontrols the DOT correction and grayscale values for each color of each LED.
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1.1 Requirements
1.2 Setup
Introduction
The user enters the LED DOT correction and grayscale information into the LED Frame Designersoftware. The software then communicates with the TLC5940EVM via an interface board. This interfaceboard, the TUSB3210GENPDK, generates the individual data signals necessary to program theTLC5940EVM so that it properly drives the LEDs.
In order to operate this EVM, the following components must be connected and properly configured. Allcomponents, software, and connectors are supplied in the EVM except for the host computer and the twodc power supplies.
1.1.1 Software
Texas Instruments has provided the software necessary to evaluate this EVM. Check the TLC5940product folder on the TI website for the latest revision of the software.
1.1.2 Host Computer (PC) Requirements•The host computer operating system must have either Windows XP™ or Windows 2000™ operatingsystem installed•Must have a USB port•Must have a minimum of 100 MB of free hard disk space for the LED Frame Designer programinstallation
•Must have a minimum of 256 MB of RAM to run the LED Frame Designer program
1.1.3 Power Supply Requirements•DC power source capable of supplying a minimum of 5.5 volts at 2 amps•DC power source capable of supplying 3.3 volts at 500 milliamps.
1.1.4 Printed Circuit Board Assembly
The TLC5940EVM-106 PCB contains three TLC5940 ICs that are configured in series.
1.1.5 TUSB3210GENPDK Interface Board
The TUSB3210GENPDK is the interface between the PC and the EVM. One end of theTUSB3210GENPDK connects to the PC with the supplied USB cable and the other end of theTUSB3210GENPDK connects to the EVM with the supplied SCSI-1 cable. When the user programs theLEDs to turn on or off, the PC sends the proper commands to the TUSB3210GENPDK. TheTUSB3210GENPDK receives the USB command where its firmware converts it into the proper bit streamnecessary to control the LEDs on the EVM.
The following sections describe how to setup the EVM software and hardware.
1.2.1 Software Installation
To install the software, insert the enclosed CD. Browse the contents of the CD for the "Setup.exe" file.Run this file to start the install process.
1.2.2 Hardware Setup
Refer to Figure 1 when setting up the TLC5940EVM hardware.
Attach the 50-pin ribbon cable between the TUSB3210 board and the TLC5940EVM board.
Ensure that the EEPROM on the TUSB3210 board is installed and properly seated.
Attach the 5.5-volt (2-A) power supply to the LED board between J5 (V_GB) and J6 (GND).
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1.3 Input/Output Connector Descriptions
IntroductionAttach the 3.3-volt (500-mA) power supply to the LED board between J4 (V_CC) and J7 (GND).
Connect the host computer to the TUSB3210 board using the USB cable. If the computer is running, amessage about installing new hardware may be displayed. Follow the on-screen instructions and allowwindows to install the default drivers for this device. Note that the USB board appears to windows as ageneric human interface device (such as a keypad or a mouse), so there is no custom driver to install.
Figure 1. Hardware Setup
1.3.1 J1 – Interface Connector
J1 provides easy access to all signals necessary to control the TLC5940EVM. This connector is useful forinterfacing the customer controller board to the EVM. Refer to the data sheet for a more detaileddescription of each signal’s function. Do not actively drive the same signals on J1 and J3 at the sametime. As shown on the schematic, these signals from J1 are buffered before reaching the TLC5940 ICs.
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Introduction
Table 1. J1 – Interface Connector
Pin
Pin Symbol Signal Name I/O FunctionNumber
1 SIN_RED Serial data input red Input Serial data input for the red LED IC. This is also the serial data inputwhen all three TLC5940 ICs are connected in cascade mode(serially).2 SOUT_R Serial data output red Output Serial data output from the red LED IC3 SIN_GREEN Serial data input green Input Serial data input for the green LED IC4 SOUT_G Serial data output green Output Serial data output for the green LED IC5 SIN_BLUE Serial data input blue Input Serial data input for the blue LED IC6 SOUT_B Serial data output blue Output Serial data output for the blue LED IC. This is also the serial dataoutput in cascade mode.7 SCLK Serial data clock Input Serial data input clock8 XLAT Data latch Input Rising edge latches data from shift register into the device9 BLANK Output enable Input Output enable for all channels. Outputs are disabled when BLANK ishigh.10 GSCLK GS PWM Clock Input Grayscale clock signal for 12-bit PWM dimming11 DCPRG DC PRG Mode Input Selects either the internal register or the internal EEPROM when inDOT correction mode.12 XDOWN Error signal Output Error flag (LOD and TEF) output. Note: XDOWN signal of all threedevices is tied together.13 VPRG_IN VPRG Signal Input This signal is buffered and combined with the /22V_EN signal to setthe VPRG voltage on the TLC5940 ICs.14 /22V_EN 22V Enable Input This is an active low enable signal that turns on the 22V powersupply that is used to program the internal EEPROM on theTLC5940 ICs.15 BUF_EN Buffer enable signal Input This is an active low enable signal that turns on the buffer for thecontrol signals on the EVM.16 GND Ground Power Signal ground
1.3.2 J2 – Power Connector
This connector supplies power to the EVM. Table 2 shows pin assignments and Table 3 shows the powerrequirements of the EVM. Ensure that the input power has the required current capability. The powerinputs to this connector are identical to the power inputs on J4, J5, J6, and J7.
Table 2. J2 – Power Connector
Pin Number Pin Symbol Function
1, 2 V_CC Supplies bias power for the ICs on the EVM board3, 4, 5, 6, 11, 12 GND Power ground7, 8 V_GB Supplies power to drive the LEDs. V_GB is connected to the anode of all three colors of eachRGB LED.9, 10 V_R Not connected
Table 3. EVM Power Requirements
Pin Number Pin Symbol Voltage Range Max Current
1, 2 V_CC 3.3 V ±0.1 V > 500 mA7, 8 V_GB 4.0 V – 17 V > 2000 mA
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1.4 Jumper Descriptions
1.5 Data Input Modes
Introduction
1.3.3 J3 – Interface Connector
This connector is used to connect the TLC5940 EVM to the TUSB3210 interface board. The signals arethe same as on connector J1.
Table 4. J3 – Power Connector
Pin DirectionPin Symbol Signal Name FunctionNumber (at board)
19 /22V_EN 22V Enable In This is an active low enable signal that turns on the 22Vpower supply that is used to program the internal EEPROMon the TLC5940 ICs.20 VRPG_IN VPRG Data In This signal is buffered and combined with the /22V_EN signalto set the VPRG voltage on the TLC5940 ICs.21 XDOWN Error signal Out Error flag (LOD and TEF) output. Note: XDOWN of all threedevices is tied together.22 DCPRG DC PRG Mode In Selects either the internal register or the internal EEPROMwhen in DOT correction mode23 GSCLK GS PWM Clock In Grayscale clock signal for 12-bit PWM dimming24 BLANK Output enable In Output enable for all channels. Outputs are disabled whenBLANK is high.25 XLAT Data latch In Rising edge latches data from shift register into the device26 SCLK Serial data clock In Serial data input clock27 SOUT_B Serial data output blue Out Serial data output for the blue LED IC. This is also the serialdata output in cascade mode28 SIN_BLUE Serial data input blue In Serial data input for the blue LED IC29 SOUT_G Serial data output green Out Serial data output for the green LED IC30 SIN_GREEN Serial data input blue In Serial data input for the blue LED IC31 SOUT_R Serial data output red Out Serial data output for the red LED IC32 SIN_RED Serial data input red In Serial data input for the red LED IC. This is also the serialdata input when all three TLC5940 ICs are connected incascade mode (serially).43,44 3.3V 3.3V Bias In This pin is the 3.3V bus from the TUSB3210 interface board.It is not connected to the V_CC pins on the PWB. It can beconnected to V_CC on the PWB by inserting a 0- Ωresistor inR18.47, 48, GND Ground Power Signal ground49, 50
1.4.1 JP1, JP2, JP3 – LED Test Current
These jumpers provide an easy place to measure the current flowing through the D0 red, green, and blueLEDs. To measure the current, through an LED, remove the jumper and connect a current meter acrossthe jumper pins. Note that no current can flow through the LEDs if the jumpers are removed and a currentmeter is not installed.
The TLC5940EVM-106 can be configured to accept data in two different modes: serially or in parallel. Thedefault configuration is serial mode. The EVM can be reconfigured for parallel data input by modifyingresistors R2, R3, R4, R6, R7, and R8 according to Table 5.
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1.6 EVM Operation
Introduction
Table 5. Data Input Mode Jumper Configurations
Data Input Mode Data Input Pins Data Output Pins 0- ΩResistors Open Resistors
Serial data input mode (default) SIN_RED SOUT_B R3, R7 R2, R4, R6, R8Parallel data input mode SIN_RED, SOUT_R, R2, R4, R6, R8 R3, R7SIN_GREEN, SOUT_G,SIN_BLUE SOUT_B
1.5.1 Serial Data Input Mode
The default configuration is a serial data input connection. In this mode, each of the three TLC5940 datastreams is connected serially. Data from the TUSB3210 enters the TLC5940 board on the SIN_RED pin.This data goes through the on-board buffer and into the SIN pin on the red TLC5940. The data passesthrough this IC and through the green TLC5940 before going into the blue TLC5940. Once the datastream has filled up the internal registers in all three TLC5940 ICs, it is latched into all ICs at the sametime.
1.5.2 Parallel Data Input Mode
When reconfigured for parallel data input, each of the three TLC5940 ICs is driven from a different dataline. Data goes into the EVM on the SIN_RED, SIN_GREEN, and SIN_BLUE inputs at the same time. Thedata then goes through the on-board buffer and into the SIN pins of each TLC5940. The software onlyoperates in serial mode. The user must provide a driver and software to operate in parallel mode.
1.6.1 Turning on the EVM
After the software is installed and the hardware is connected as described earlier in this document, theEVM is ready for use. The startup procedure for the EVM is as follows:1. Connect all hardware.2. Turn on the 3.3V and 5.5V power supplies3. Run the LED Frame Designer software
If the USB cable is removed and reinserted while the software is running, or if power is removed fromVCC, the DOT correction data can become corrupted. To correct this problem, either push the RESETbutton on the TUSB3210 PWB or click on the PLAY button in the software.
The default state at startup is to program the LED drivers to 100% DOT correction and 100% grayscalemode. This produces a white light from the LEDs.
1.6.2 Signal Conditioning Buffer
The TLC5940EVM PWB contains a buffer to condition the input signals to the EVM. This buffer,SN74AVC16244, eliminates any noise on the input signals, generates fast, clean rise and fall times, andimproves the drive capability of the signal. This circuitry is not necessary for operation of the TLC5940 IC.It was added to the EVM to eliminate problems that could be caused by noisy drive signals in a test setup.
1.6.3 EEPROM Programming Voltage Supply Circuit
The TLC5940 requires 22V on the VPRG pin in order to program the internal EEPROM. This EEPROMprogramming voltage supply circuit uses a TPS61040 IC to provide 22V for this purpose. The circuitremains off until the /22V_EN signal is pulled low.
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2 Board Layout
Board Layout
1.6.4 Switching Circuit for VPRG
The VPRG pin on the TLC5940 performs three functions. The TLC5940 is in grayscale mode when VPRG= GND and in DOT correction mode when VPRG = VCC. When VPRG = 22V, the TLC5940 can programDOT correction data into its internal nonvolatile EEPROM. The Switching Circuit for VPRG consisting ofQ1, Q2, Q3, D18, and supporting resistors is designed to switch the VPRG pins on each TLC5940between these three voltages. Table 6 shows the truth table for generating the VPRG voltage.
Table 6. Data Input Mode Jumper Configurations
/22V_EN VPRG_IN DCPRG VPRG Pin on TLC5940 Description
0 1 0 22 V 22V is enabled and applied to VPRG, but the data cannot bewritten to the EEPROM because DCPRG is low.0 1 1 22 V 22V is enabled and applied to VPRG. The EEPROM can nowbe programmed.1 0 1 0 V Grayscale input mode1 1 1 3.3 V DOT correction input mode
This chapter provides the TLC5940EVM-106 board layout.
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2.1 Layout
Board Layout
Figure 2. Assembly Layer
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Board Layout
Figure 3. Top Layer Routing
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Board Layout
Figure 4. Layer 2 Routing
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