EVALUATION KIT AVAILABLE 2-Wire Interfaced, 2.7V to 5.5V MAX6955 LED Display Driver with I/O Expander and Key Scan General Description Benefits and Features The MAX6955 is a compact display driver that interfaces Simplifies Driving 5 x 7 Matrix LED Displays microprocessors to a mix of 7-segment, 14-segment, Drives Common-Cathode Monocolor and Bicolor 2 and 16-segment LED displays through an I C-compati- LED Displays ble 2-wire serial interface. The MAX6955 drives up to 16 Drives Up to 16 Digits 7-Segment, 8 Digits 14-Segment, digits 7-segment, 8 digits 14-segment, 8 digits 16-seg- 8 Digits 16-Segment, 128 Discrete LEDs, or a ment, or 128 discrete LEDs, while functioning from a Combination of Digit Types supply voltage as low as 2.7V. The driver includes five 2.7V to 5.5V Operation I/O expander or general-purpose I/O (GPIO) lines, some Standard 2-Wire Interface Supports a Variety of or all of which can be configured as a key-switch reader. Microprocessor Architectures The key-switch reader automatically scans and 2 400kbps 2-Wire I C-Compatible Interface debounces a matrix of up to 32 switches. Integrated Flexibility Supports Different Application Included on chip are full 14- and 16-segment ASCII Requirements 104-character fonts, a hexadecimal font for 7-segment Built-In ASCII 104-Character Font for 14-Segment displays, multiplex scan circuitry, anode and cathode and 16-Segment Digits and Hexadecimal Font for drivers, and static RAM that stores each digit. The max- 7-Segment Digits imum segment current for the display digits is set using 16-Step Digit-by-Digit Digital Brightness Control a single external resistor. Digit intensity can be inde- pendently adjusted using the 16-step internal digital Display Blanked on Power-Up brightness control. The MAX6955 includes a low-power Automatic Blinking Control for Each Segment shutdown mode, a scan-limit register that allows the 10A (typ) Low-Power Shutdown (Data Retained) user to display from 1 to 16 digits, segment blinking Five GPIO Port Pins Can Be Configured as Key-Switch (synchronized across multiple drivers, if desired), and a Reader to Scan and Debounce Up to 32 Switches with test mode, which forces all LEDs on. The LED drivers n-Key Rollover are slew-rate limited to reduce EMI. IRQ Output when a Key Input Is Debounced For an SPI-compatible version, refer to the MAX6954 Slew-Rate-Limited Segment Drivers for Lower EMI data sheet. An evaluation kit (EV kit) for the MAX6955 is 36-Pin SSOP and 40-Pin DIP and TQFN Packages available. Automotive Temperature Range Standard Covers Usage in Harsh Environments Applications Functional Diagram Set-Top Boxes Bar Graph Displays Panel Meters Audio/Video Equipment GPIO P0 TO P4/IRQ White Goods AND KEY-SCAN CONTROL PWM CURRENT ISET O0 TO O18 BRIGHTNESS SOURCE LED CONTROL DRIVERS Ordering Information DIGIT OSC MULTIPLEXER DIVIDER/ PART TEMP RANGE PIN-PACKAGE COUNTER NETWORK OSC OUT CHARACTER MAX6955AAX+ -40C to +125C 36 SSOP GENERATOR MAX6955 ROM MAX6955ATL+ -40C to +125C 40 TQFN-EP* *EP = Exposed pad. BLINK BLINK CONTROL +Denotes a lead(Pb)-free/RoHS-compliant package. CONFIGURATION REGISTER RAM Pin Configurations and Typical Operating Circuits appear SCL at end of data sheet. AD0 2-WIRE SERIAL INTERFACE AD1 SDA 19-2548 Rev 4 7/152-Wire Interfaced, 2.7V to 5.5V MAX6955 LED Display Driver with I/O Expander and Key Scan Absolute Maximum Ratings Voltage (with Respect to GND) Continuous Power Dissipation (T = +70C) A V+.........................................................................-0.3V to +6V 36-Pin SSOP (derate at 11.8mW/C above +70C) .....941mW SCL, SDA, AD0, AD1 ...........................................-0.3V to +6V 40-Pin TQFN (derate at 25.6mW/C above +70C)....2051.3mW All Other Pins............................................-0.3V to (V+ + 0.3V) Operating Temperature Range Current (T to T ) ...............................................-40C to +125C MIN MAX O0O7 Sink Current......................................................935mA Junction Temperature......................................................+150C O0O18 Source Current .................................................55mA Storage Temperature Range .............................-65C to +150C SCL, SDA, AD0, AD1, BLINK, OSC, OSC OUT, ISET....20mA Lead Temperature (soldering, 10s) .................................+300C P0, P1, P2, P3, P4/IRQ....................................................40mA GND .....................................................................................1A Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC Electrical Characteristics (Typical Operating Circuit, V+ = 2.7V to 5.5V, T = T to T , unless otherwise noted.) (Note 1) A MIN MAX PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Operating Supply Voltage V+ 2.7 5.5 V Shutdown mode, all T = +25C 10 35 A Shutdown Supply Current I digital inputs at V+ A SHDN T = T to T 40 or GND A MIN MAX All segments on, all T = +25C 22 30 digits scanned, A intensity set to full, Operating Supply Current I+ mA internal oscillator, no display or OSC OUT T = T to T 35 A MIN MAX load connected OSC = RC oscillator, R = 56k , SET 4 C = 22pF, V+ = 3.3V Master Clock Frequency f SET MHz OSC OSC driven externally 1 8 Dead Clock Protection Frequency f 95 kHz OSC OSC Internal/External Detection V 1.7 V OSC Threshold OSC High Time t 50 ns CH OSC Low Time t 50 ns CL OSC = RC oscillator, R = 56k , SET Slow Segment Blink Period f 1s SLOWBLINK C = 22pF, V+ = 3.3V SET OSC = RC oscillator, R = 56k , SET Fast Segment Blink Period f 0.5 s FASTBLINK C = 22pF, V+ = 3.3V SET Fast or Slow Segment Blink Duty 49.5 50.5 % Cycle www.maximintegrated.com Maxim Integrated 2