LM3553SDEV

Application Report SNVA319B – February 2008 – Revised April 2013 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface ..................................................................................................................................................... ABSTRACT This application note describes how to operate the LM3553 Evaluation Module. 1 2 3 4 5 6 Contents Typical Application Drawing ............................................................................................... 2 Bill of Materials .............................................................................................................. 2 Schematic .................................................................................................................... 3 LM3553 Evaluation Board Layout ........................................................................................ 3 Board Operation ............................................................................................................. 4 5.1 Basic Connections ................................................................................................. 4 5.2 External Control Interface Connection .......................................................................... 5 5.3 Operation Description ............................................................................................. 5 Software Interface Information ........................................................................................... 11 List of Figures 1 Top Layer .................................................................................................................... 3 2 Mid-Layer 1 .................................................................................................................. 4 3 Mid-Layer 2 .................................................................................................................. 4 4 Bottom Layer (unmirrored) ................................................................................................. 4 5 Data Validity Diagram ...................................................................................................... 5 6 Start and Stop Conditions.................................................................................................. 6 7 Write Cycle w = write (SDA = "0") ack = acknowledge (SDA pulled down by the slave) id = chip address, 53h for LM3553 ............................................................................................................. 6 8 FEN Terminated Pulse.................................................................................................... 10 9 Safety Timer Terminated Pulse .......................................................................................... 10 10 TX Terminated Pulse 11 12 13 ..................................................................................................... GUI Start-Up ............................................................................................................... Generic Read/Write Field................................................................................................. Drop Down Menu .......................................................................................................... 11 12 12 12 List of Tables ................................................................................... 1 M/F Functionality Configuration Table 2 RSET Selection Table ........................................................................................................ 9 8 3 LM3553 Functionality Truth Table ....................................................................................... 10 All trademarks are the property of their respective owners. SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 1 Typical Application Drawing www.ti.com 1 Typical Application Drawing 2 Bill of Materials Component Symbol Value Package Manufacturer Part # LM3553 -- SDF12A LLP12 Texas Instruments LM3553SDX LM3553 Evaluation Board -- -- Texas Instruments 551600092-001 RevA LED1,LED2 White LED -- Philips Lumiled LXCL-PWF3 CIN 10µF, 6.3V 0603 Murata GRM188R60J106ME47D COUT 4.7µF, 25V 0805 Murata GRM21BR61E475KA12L L1 2.2µH 3mm x 3mm x 1.2mm Toko FDSE0312-2R2M RSET 33kΩ 0402 Vishay Dale CRCW040233K0FKED D1 1.5A, 30V ROHM RB070M-30 RSDA, RSCL, RFEN, RMF, RTX 10kΩ 0402 Vishay Dale CRCW040210K0JNED 2 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Schematic www.ti.com 3 Schematic 4 LM3553 Evaluation Board Layout Figure 1. Top Layer SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 3 Board Operation www.ti.com Figure 2. Mid-Layer 1 Figure 3. Mid-Layer 2 Figure 4. Bottom Layer (unmirrored) 5 Board Operation 5.1 Basic Connections To operate the LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface, connect a supply voltage (2.7V-5.5V) between board connectors VIN and GND and attach an I2C interface using one of the methods described in Section 5.2. Default Jumper Connections: • M/F: Connected to "-". To enable the LM3553 evaluation board, connect the M/F header to the '+' using the provided jumper. This will place the LM3553 evaluation board into normal operation mode and out of Hardware Reset • TX: Connected to "-". By default, this setting will allow the full-scale flash to occur. Moving the TX jumper to the "+" position during a flash will force the LM3553 in a lower current TX mode. This TX mode level is equal to the level stored in the Torch Control Register. • FEN: Connected to "-". By default, this setting will not allow an externally controlled flash even to 4 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Board Operation www.ti.com occur. Moving the FEN jumper to the "+" position will start a flash event. The flash event will remain active until the FEN pin is driven back to the "-" position or the internal timeout time lapses, which ever occurs first. With the default jumper connections made, the board will be ready to operate once an input voltage and an I2C interface generator (external or USB docking board) are connected. NOTE: For the evaluation board to work properly, the OVP bit in the Multi-Function/Options Register must be set to a 1 (18.9V OVP). If this bit is not enabled, the part will not boost to the required voltage and performance will be degraded. 5.2 External Control Interface Connection The LM3553 Evaluation Board provides two ways to connect an I2C compatible interface to the LM3553 IC. The first method to connect the interface is through a set of connectors on the bottom of the evaluation board that allow the board to plug into the USB interface board directly. The second method of interface connection is through a header strip located on the left hand side of the evaluation board. There are pins available to connect VIO (contoller reference voltage), SCL (Interface Clock Line), and SDA (Interface Data Line) each separated by a ground pin. The evaluation board has two external pull-ups that connect both SCL and SDA to VIO to compliment the open drain inputs found on the LM3553. Section 5.3 describes the internal registers and I2C compatible interface in greater detail. 5.3 Operation Description I2C Compatible Interface 5.3.1 5.3.1.1 Data Validity The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, the state of the data line can only be changed when CLK is LOW. Figure 5. Data Validity Diagram A pull-up resistor between VIO and SDA must be greater than [(VIO-VOL) / 3.7mA] to meet the VOL requirement on SDA. Using a larger pull-up resistor results in lower switching current with slower edges, while using a smaller pull-up results in higher switching currents with faster edges. 5.3.1.2 Start and Stop Conditions START and STOP conditions classify the beginning and the end of the I2C session. A START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. A STOP condition is defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and STOP conditions. The I2C bus is considered to be busy after a START condition and free after a STOP condition. During data transmission, the I2C master can generate repeated START conditions. First START and repeated START conditions are equivalent, function-wise. The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, the state of the data line can only be changed when CLK is LOW. SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 5 Board Operation www.ti.com Figure 6. Start and Stop Conditions 5.3.1.3 Transferring Data Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first. Each byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the master. The master releases the SDA line (HIGH) during the acknowledge clock pulse. The LM3553 pulls down the SDA line during the 9th clock pulse, signifying an acknowledge. The LM3553 generates an acknowledge after each byte has been received. After the START condition, the I2C master sends a chip address. This address is seven bits long followed by an eighth bit which is a data direction bit (R/W). The LM3553 address is 53h. For the eighth bit, a “0” indicates a WRITE and a “1” indicates a READ. The second byte selects the register to which the data will be written. The third byte contains data to write to the selected register. Figure 7. Write Cycle w = write (SDA = "0") ack = acknowledge (SDA pulled down by the slave) id = chip address, 53h for LM3553 5.3.1.4 I2C Compatible Chip Address The chip address for LM3553 is 1010011, or 53hex. 6 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Board Operation www.ti.com 5.3.1.5 Internal Registers of LM3553 Register Internal Hex Address Power On Value General Purpose Register 0x10 0001 1000 Multi-Function Pin Control Register 0x20 1110 0000 Current Step Time Register 0x50 1111 1100 Torch Current Control Register 0xA0 1000 0000 Flash Current Control Register 0xB0 1000 0000 Flash Duration Control Register 0xC0 1111 0000 5.3.1.5.1 General-Purpose Register EN0-EN1: Set Flash LED mode Indicator Mode sets ILED = 20mA. In this mode, D1 is enabled and D2 is disabled. VM: Enables Voltage Mode. Current sinks D1 and D2 are turned off and the LM3553 will operate in a regulated voltage boost mode. Setting the VM bit to a '1' does not override the EN0 and EN1 bits stored in the general purpose register. The default setting is '0'. If the LM3553 is in Voltage Mode and an indicator, torch or flash command is issued, the LM3553 will turn on the D1 and D2 current sources and begin regulating the output voltage to a value equal to VFB (350mV or 450mV) + VLED. VM EN1 EN0 Function 0 0 0 Shutdown 0 0 1 Indicator Mode 0 1 0 Torch Mode 0 1 1 Flash Mode 1 0 0 Voltage Mode 1 0 1 Indicator Mode 1 1 0 Torch Mode 1 1 1 Flash Mode VFB: Selects the regulation voltage for the LM3553. Setting this VFB bit to a '0' sets the regulation voltage to 450mV while setting the VFB bit to a '1' sets the regulation voltage to 350mV. Setting the VFB bit to a '1' during torch mode and/or lower current flash modes (ILED < 1A) will help improve the LED efficiency of the LM3553. 5.3.1.5.2 M/F Pin Control Register RESET: Enables M/F as hardware RESET. '0' = Hardware RESET, .'1' = GPIO or current sink depending on the MODE bit. Default = '0' MODE: Sets M/F mode. Default for M0DE = '0'. '0' = GPI, and'1' = GPO SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 7 Board Operation www.ti.com NOTE: When M/F is configured as an input, data is transfered from GPI to DATA whenever an I2C write command is issued to the LM3553. When configuring M/F as a GPO, the first write needs to take the LM3553 out of RESET mode and a second write can then set the pin to the GPO. DATA: GPIO Data. When the M/F is configured as an output (GPO), DATA sets the GPO level. Example: DATA = '1', M/F is set high or logic '1'. When the M/F pin is configured as an input (GPI), DATA stores the GPI level. Example: M/F = '1', DATA will be set to a '1'. Default for DATA = '0'. OVP: Enables high-voltage OVP (OVP Bit ='1') or low-voltage OVP (OVP Bit ='0'). Default = low-voltage mode '0' OCL: SW Pin Current Limit Selector Bit: If OCL = '0', the inductor current limit is 2.5A typ. If OCL = '1', the inductor current limit is 1.7A typ. Table 1. M/F Functionality Configuration Table 5.3.1.5.3 RESET MODE M/F Function 0 X RESET 1 0 GPI 1 1 GPO Current Step Time Register ST1-ST0: Sets current level stepping time for D1 and D2 during the beginning and end of the flash or torch current waveform. '00' = 25µs, '01' = 50µs, '10' = 100µs, '11' = 200µs. The current ramp-up/ramp-down times can be approximated by the following equation: TRAMPUP/RAMPDOWN = (NFLASH - NSTART + 1) × tSTEP where N is equal to the decimal value of the brightness level (0 ≤ NFLASH ≤ 127 and 0 ≤ NSTART ≤ 31). NSTART = NTORCH if Torch is enabled before going into a flash. If going straight into a flash from an off-state, NSTART = 0 5.3.1.5.4 Torch Current Control Register TC6-TC0: Sets Torch current level for D1 and D2. xxx1 1111 = Full-scale 5.3.1.5.5 Flash Current Control Register FC6-FC0: Sets Flash current level for D1 and D2. x111 1111 = Full-scale 8 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Board Operation www.ti.com 5.3.1.5.6 Current Level Equation The Full-Scale Flash Current Level is set through the use of an external resistor (RSET) connected to the ISET pin. The RSET selection equation can be used to set the current through each of the two current sinks, D1 and D2. RSET = 6770 × 1.24V ÷ IDx Table 2. RSET Selection Table IFlash = ID1 + ID2 RSET 500mA 33.6kΩ 600mA 28kΩ 1A 16.8kΩ 1.2A 14kΩ The current through each current sink, D1 and D2, can be approximated by the following equation using the values stored in either the Torch or Flash Current Control registers. IFLASH≊ (N + 1) × ILED_TOTAL ÷ 128 where N is the decimal equivalent number (0 ≤ N ≤ 127 for Flash and 0 ≤ N ≤ 31 for Torch) stored in the Torch or Flash Current control registers and ILED_TOTAL = ID1 + ID2 @ Full-scale. Brightness codes 0 through 4 are repeated and each sets the total LED current to approximately 40mA. 5.3.1.5.7 Flash Safety Timer Control Register FD3-FD0: Sets Flash Duration for D1 and D2. 1111 = Full-scale Safety Timer Duration Code (Binary) Typical Safety Timer Duration (milliseconds) 0000 50 0001 100 0010 200 0011 300 0100 400 0101 500 0110 600 0111 700 1000 800 1001 900 1010 1000 1011 1100 1100 1200 1101 1300 1110 1400 1111 3200 SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 9 Board Operation www.ti.com Table 3. LM3553 Functionality Truth Table EN1 EN0 FEN TX Result 0 0 0 0 Shutdown 0 0 0 1 Shutdown 0 0 1 0 Flash 0 0 1 1 Torch 0 1 0 0 Indicator 0 1 0 1 Indicator 0 1 1 0 Flash 0 1 1 1 Torch 1 0 0 0 Torch 1 0 0 1 Torch 1 0 1 0 Flash 1 0 1 1 Torch 1 1 0 0 Flash 1 1 0 1 Torch 1 1 1 0 Flash 1 1 1 1 Torch Figure 8. FEN Terminated Pulse Figure 9. Safety Timer Terminated Pulse 10 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Software Interface Information www.ti.com Figure 10. TX Terminated Pulse 6 Software Interface Information In order to fully evaluate the LM3553 part, an “I2C Compatible” interface must be used for any functionality to occur. A detailed description of the interface control is described in the LM3553 data sheet. TI has created an I2C compatible interface generation program and USB docking board that can help exercise the part in a simple way. Contained in this document is a description of how to use the USB docking board and interface software. The LM3553 evaluation board has the means to “plug into” the USB docking board. The USB docking board provides all of the control signals for the simple interface. Power to the part must be provided externally. A standard USB cable must be connected to the board from a PC. The I2C compatible interface program provides all of the control that the LM3553 part requires. For proper operation, the USB docking board should be plugged into the PC before the interface program is opened. Once connected, and the program is executed, a basic interface window will open. SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 11 Software Interface Information www.ti.com Figure 11. GUI Start-Up At the top of the interface, the user can read or write to any of the data registers on the LM3553 part using the two pull down menus (for the slave i.d. and the desired data address), the data field, and the read and write buttons. Figure 12. Generic Read/Write Field Figure 13. Drop Down Menu Just below the pull down menus are convenient toggle buttons to set/reset the control bits in the Control Registers. 12 AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback Copyright © 2008–2013, Texas Instruments Incorporated Software Interface Information www.ti.com • • • • • • VFB: Toggles the Feedback voltage between 450mV (default) and 350mV. When pressed, the feedback voltage will be set to 350mV Volt Mode: Places the LM3553 into voltage output mode. When depressed, the part will output 4.98V. EN1 and EN0: These bits place the part into either shutdown, indicator, torch or flash. '00' = Shutdown, '01'=Indicator, '10'=Torch, '11'=Flash. OCL: Toggles the inductor current limit between 2.5A (default) and 1.7A. When the OCL button is depressed, the current limit will be set to 1.7A OVP: Toggles the over-voltage protection level between 5.6V (default) and 18.9V. When the OVP button is depressed, the OVP level will be set to 18.9V Data, I/O, HWEN: These buttons control the functionality of the M/F pin. Please refer to the M/F pin description for a detailed description of the M/F pin operation. • • • • Flash: Starts a Flash event by setting the EN1 and EN0 bits to 1's. Torch: Starts a Torch event by setting the EN1 bit to a '1' and EN 0 bit to a '0'. Indicator: Starts an Indicator event by setting the EN1 bit to a '0' and EN 0 bit to a '1'. Disable: Shuts down the LM3553 by setting the EN1 and EN0 bits to 0's. • • • Torch Slider: Sets the Torch brightness to any allowable brightness code (0 to 31) Flash Slider: Sets the Flash brightness to any allowable brightness code (0 to 127) Flash Duration: Sets the Flash duration to one of the 16 built-in time durations (0 to 15) NOTE: If the part is enabled to any level of brightness or state and the program is closed (by either hitting the OK or cancel buttons) , the LM3553 part will remain in the last controlled state. SNVA319B – February 2008 – Revised April 2013 Submit Documentation Feedback AN-1780 LM3553 1.2A Dual Flash LED Driver System with I2C Compatible Interface Copyright © 2008–2013, Texas Instruments Incorporated 13 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as “components”) are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. 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