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Technical content
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64 LED Driver for Mobile Applications with Error Detection
1 General Description
external clock is also supported. The device is available in a TQFN(4x4)-24 package. Figure 1. AS1117 - Typical Application Diagram
2 Key Features
3 Applications
sonal electronic applications. Table 1. Available Products
4 Pinout
Figure 2. Pin Assignments (Top View) Table 2. Pin Descriptions SDA 22 Serial-Data I/O. Open drain digital I/O I²C data pin. KEY 8 Keyscan Input. Keyscan lines for key readback. Can be used for self-adressing. External Drivers on page 19). SCL 11 Serial-Clock Input. 3.4MHz maximum rate. IRQ 21 Interupt Request Output. Open drain pin. decimal point drive that source current to the display. GND with a 0.1µF capacitor to avoid power supply ripple. the circuit-board ground plane to maximize power dissipation.
5 Absolute Maximum Ratings
Table 3. Absolute Maximum Ratings packages is matte tin (100% Sn).
6 Electrical Characteristics
Table 4. Electrical Characteristics Table 5. Logic Inputs/Outputs Characteristics
- The Min / Max values of the Timing Characteristics are guaranteed by design.
- All limits are guaranteed. The parameters with min and max values are guaranteed with production tests or SQC
(Statistical Quality Control) methods. Figure 3. Timing Diagram Table 6. Timing Characteristics
7 Typical Operating Characteristics
Figure 4. Display Scan Rate vs. Supply Voltage; Figure 5. Display Scan Rate vs. Temperature; Figure 6. Segment Current vs. Temperature; Figure 7. Segment Current vs. R SET;
8 Detailed Description
Figure 16. AS1117 - Block Diagram Figure 17. ESD Structure
data line HIGH to enable the master to generate the STOP condition. a number of data bytes. The slave returns an acknowledge bit after the slave address and each received byte. repeated START condition is also the beginning of the next serial transfer, the bus will not be released. transfer. Address recognition is performed by hardware after reception of the slave address and direction bit. nized as the beginning and end of a serial transfer. devices have the predefined adress 0000000. A single command for self-addressing will update all connected AS1117. The address byte (see Figure 20) is the first byte received following the START condition from the master device. Figure 20. I²C Device Address Byte
- The default slave address is factory-set to 0000000.
selected; when set to a 0 a write operation is selected. Following the START condition, the AS1117 monitors the I²C bus, checking the device type identifier being transmitted. bit, the slave device outputs an acknowledge signal on the SDA line.
The AS1117 operation, (see Table 7) is determined by a command byte (see Figure 21 on page 11). Figure 21. Command Byte Figure 22. Command and Single Data Byte Received Figure 23. Setting the Pointer to a Address Register to select a Data Register for a Read Operation Figure 24. Reading nBytes from AS1117
1 Byte
into shutdown mode. At this time, all registers should be programmed for normal operation. Register (see page 17) is set to the minimum values. Digit-Registers maintain their data. Register bit D7 (page 13) = 0. writing to the Shutdown Register.
- All registers are selected using a 8-bit address word, and communication is done via the I²C interface.
without rewriting the whole register contents. down, display test and features selection registers. Table 7. Register Address Map
The Shutdown Register controls AS1117 shutdown mode. on). Table 10 on page 14 lists some examples of the possible settings for the Decode Enable Register bits. Note: A logic high enables decoding and a logic low bypasses the decoder altogether. D7 = 1 turns the decimal point on). Table 10 on page 14 lists the code-B font; Table 11 on page 14 lists the HEX font. Table 8. Shutdown Register Format (Address (HEX) = 0x0C))
AS1117. Table 12 on page 15 shows the 1:1 pairing of each data bit to the appropriate segment line. Figure 25. Standard 7-Segment LED Intensity Control and Inter-Digit Blanking Table 9. Decode Enable Register Format Examples Code-B/HEX decode for digits 0,2,5. Table 10. Code-B Font The decimal point can be enabled with every character by setting bit D7 = 1. Table 11. HEX Font
devices have the predefined adress 0000000. A single command for selfaddressing will update all connected AS1117. Note: A short writes a logical “0” whereas an open writes a logical “1” as address bit. these two nodes cannot be used as a key. Additionally the debounce time is disabled for these two bits. IRQ is triggered. A short writes a logical “0” whereas an open writes a logical “1” as keyscan register bit. The decimal point can be enabled with every character by setting bit D7 = 1. Table 12. No-Decode Mode Data Bits and Corresponding Segment Lines Table 13. Self Addressing Register (Address (HEX) = 0x2D)) Table 14. LED Diagnostic Register Address
Note: All settings of the digit- and control-registers are maintained. These eight registers contain the result of the LED open/short test for the individual LED of each digit. Note: If one or more short occures in the LED array, detection of individual LED fault could become ambiguous. Table 15. Testmode Register Summary Table 16. Testmode Register Bit Description (Address (HEX) = 0x0F)) Table 17. LED Diagnostic Register Address
down to 1/16 of the peak current set by RSET. update frequency is typically 700Hz. If the number of digits displayed is reduced, the update frequency is increased. The frequency can be calculated using 10 x fOSC/(N+2), where N is the number of digits. Note: To avoid differences in brightness this register should not be used to blank parts of the display (leading zeros). Table 18. Intensity Register Format Table 19. Intensity Register Address Table 20. Scan-Limit Register Format (Address (HEX) = 0x0B))
and resetting the blink timing. Note: At power-up the Feature Register is initialized to 0. Table 21. Feature Register Summary Table 22. Feature Register Bit Descriptions (Address (HEX) = 0xXE) Enables and disables various device features. 0 = Internal oscillator is used for system clock. 1 = Pin CLK of the serial interface operates as system clock input. Resets all control registers except the Feature Register. 0 = Reset Disabled. Normal operation. Register) identically after power-up. Note: The Digit Registers maintain their data. Selects display decoding for the selected digits (Table 9 on page 14). 0 = Enable Code-B decoding (see Table 10 on page 14). 1 = Enable HEX decoding (see Table 11 on page 14). D4 blink_en 0R / W Enables blinking. 0 = Disable blinking. 1 = Enable blinking. 0 = Blink period typically is 1 second (0.5s on, 0.5s off). 1 = Blink period is 2 seconds (1s on, 1s off). bit D7 determines how blinking starts. 0 = Blinking starts with the display turned off. 1 = Blinking starts with the display turned on.
9 Typical Application
that the devices drive high currents. Note: The display brightness can also be logically controlled (see Intensity Control Register (0x0A) on page 16). DUTY is the duty cycle set by intensity register (page 17). In this example the maximum ambient temperature must stay below 123.61°C. Table 24. RSET vs. Segment Current and LED Forward Voltage, VDD = 4.0V & 5.0V
The AS1117 is available in the TQFN(4x4)-24 package. Figure 28. TQFN(4x4)-24 Package Notes:Unilateral coplanarity zone applies to the exposed heat sink slug as well as the terminals.
- All dimensions are in millimeters; angles in degrees.
- Dimension b applies to metallized terminal and is measured between 0.25mm and 0.30mm from terminal tip.
Dimension L1 represents terminal full back from package edge up to 0.1mm is acceptable.
- Coplanarity applies to the exposed heat slug as well as the terminal.
- Radius on terminal is optional.
The devices are available as the standard products shown in Table 25. Note: All products are RoHS compliant. Table 25. Ordering Information
www.austriamicrosystems.com/LED-Driver-ICs/AS1117 Revision 1.00 23 - 23 AS1117 Datasheet Copyrights Copyright © 1997-2010, austriamicrosystems AG, Tobelbaderstrasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered ®. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. All products and companies mentioned are trademarks or registered trademarks of their respective companies. Disclaimer Devices sold by austriamicrosystems AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. austriamicrosystems AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein or regarding the freedom of the described devices from patent infringement. austriamicrosystems AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with austriamicrosystems AG for current information. This product is intended for use in normal commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by austriamicrosystems AG for each application. For shipments of less than 100 parts the manufacturing flow might show deviations from the standard production flow, such as test flow or test location. The information furnished here by austriamicrosystems AG is believed to be correct and accurate. However, austriamicrosystems AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of austriamicrosystems AG rendering of technical or other services. Contact Information Headquarters austriamicrosystems AG Tobelbaderstrasse 30 A-8141 Unterpremstaetten, Austria Tel: +43 (0) 3136 500 0 Fax: +43 (0) 3136 525 01 For Sales Offices, Distributors and Representatives, please visit: http://www.austriamicrosystems.com/contact ams AG Technical content still valid