The Original TM1628A LED Display and Key-Scan Driver IC is a dedicated peripheral controller integrated circuit manufactured by Titan Micro Electronics. Encapsulated in a standard SOP-28 surface-mount package, it combines an internal LED display memory matrix, 7-segment / 14-segment drive outputs, an 8-level digital dimming circuit, and a 10×2 matrix key-scanning interface onto a single chip. Controlled through a high-speed 3-wire serial interface (STB, CLK, DIO), the TM1628A manages multi-digit numeric LED displays or front-panel indicator arrays while offloading refresh and keypad polling tasks from the main host microcontroller (such as Arduino, ESP32, STM32, or CH32V). It is widely utilized in front-panel control boards for home appliances, induction cooktops, microwave ovens, set-top boxes, DVD/audio receivers, and industrial instrumentation panels.

Specifications

• Part Number / Model: TM1628A / TM1628
• Manufacturer: Titan Micro Electronics (TitanMicro)
• Device Function: Multi-Segment LED Display Driver & Key-Scanning Controller
• Package Type: SOP-28 
• Operating Supply Voltage Range (VDD): 4.5V to 5.5V DC (Nominal: 5.0V DC)
• Logic High-Level Input Voltage (VIH): 0.7 × VDD to VDD (3.5V to 5.0V at VDD = 5V)
• Logic Low-Level Input Voltage (VIL): 0V to 0.3 × VDD (0V to 1.5V)
• Segment Output Current (High-Side Source): Typ. 20 mA to 50 mA per segment
• Grid Output Current (Low-Side Sink): Typ. 100 mA to 250 mA per grid
• Display Drive Matrix Modes:
  • 10 Segments × 7 Grids
  • 11 Segments × 6 Grids
  • 12 Segments × 5 Grids
  • 13 Segments × 4 Grids
• Key-Scan Matrix Capability: 10 × 2 Matrix (up to 20 discrete pushbuttons or switches)
• Dimming Control: 8-Level Pulse-Width Modulation (PWM) Software Brightness Adjustment (1/16 to 16/16 Duty Cycle)
• Host Communication Interface: 3-Wire Synchronous Serial Interface (STB - Strobe/Chip Select, CLK - Serial Clock, DIO - Bidirectional Data I/O)
• Serial Clock Frequency (fCLK): Up to 1 MHz
• Built-in Oscillator: Internal RC Oscillator (No external crystal or resonator required)
• Power Dissipation (Pd): Max. 400 mW
• Operating Ambient Temperature (Topr): -40°C to +85°C
• Storage Temperature Range (Tstg): -65°C to +150°C
• Pinout Configuration (SOP-28):
  • Pins 1 to 4: GRID4/SEG13, GRID5/SEG12, GRID6/SEG11, GRID7/SEG10 (Configurable Grid/Segment Pins)
  • Pins 5 to 7: STB (Strobe Input), CLK (Clock Input), DIO (Serial Data Input/Output)
  • Pin 8: VSS (Ground / 0V Reference)
  • Pins 9 to 10: KEY1, KEY2 (Keypad Matrix Scan Inputs)
  • Pin 11: VDD (Positive 5V Power Supply)
  • Pins 12 to 19: SEG1/KS1 to SEG8/KS8 (Segment Drivers / Key-Scan Outputs)
  • Pin 20: SEG9/KS9 (Segment Driver / Key-Scan Output)
  • Pin 21: VDD (Positive 5V Power Supply)
  • Pins 22 to 24: SEG10/KS10, GRID1, GRID2 (Segment / Grid Output Pins)
  • Pin 25: VSS (Ground / 0V Reference)
  • Pins 26 to 28: GRID3, GRID4, GRID5 (Dedicated Grid Driver Pins)

Features

• Minimal Pin Count 3-Wire Interface: Requires only 3 MCU digital GPIOs (STB, CLK, DIO) to control complex multi-digit 7-segment displays and read back up to 20 front-panel keys.
• Integrated Display RAM & Auto-Scanning: Stores display segment data in internal dual-port RAM and automatically handles high-frequency LED multiplexing without consuming MCU processing cycles.
• 8-Level Software Brightness Control: Built-in hardware duty-cycle modulator adjusts screen brightness from 1/16 to 16/16 levels via simple serial commands.
• Hardware Key De-Bouncing & Scanning: Automatically scans up to a 10×2 matrix keyboard and stores button states in internal key data registers for easy serial polling.
• Flexible Segment/Grid Output Selection: Configurable drive modes allow driving common cathode LED modules, discrete bar graphs, and individual annunciator status icons simultaneously.
• Robust Noise Immunity: High-grade CMOS design engineered specifically for electrically noisy domestic appliances and high-EMC industrial environments.

Common Applications

• Home & Kitchen Appliance Panels: Front user-interface displays on induction cookers, air fryers, microwave ovens, and electric pressure cookers.
• Consumer Entertainment Devices: Display and button control panels for set-top boxes, DVD players, audio receivers, and karaoke systems.
• Industrial Timers & Process Indicators: Multi-digit panel meters, production counters, and digital thermostat displays.
• Air Conditioning & HVAC Units: Wall-mounted climate controller panels and indoor unit status screens.
• Custom Microcontroller Projects: Offloading complex multi-digit displays and keypads in Arduino, ESP32, and Raspberry Pi DIY builds.

Usage Tips

• Logic Level Shifting with 3.3V MCUs: When interfacing the TM1628A (running at 5.0V VDD) with 3.3V microcontrollers (ESP32, STM32, RP2040), place a **1kΩ to 2.2kΩ series resistor or bidirectional logic level shifter on the DIO line** to prevent 5V read-back pulses from exceeding the 3.3V MCU pin absolute ratings.
• Power Supply Decoupling (Critical): High dynamic switching currents from multiplexing LED segments can generate supply ripples. Place a **100nF ceramic capacitor in parallel with a 10µF to 47µF electrolytic/tantalum capacitor** as close as possible across VDD (Pins 11, 21) and VSS (Pins 8, 25).
• Pull-Up Resistor on DIO Line: The DIO pin operates as an open-drain/bidirectional line during data reads. Include an external **4.7kΩ to 10kΩ pull-up resistor** from the DIO line to VDD (or MCU logic rail) to ensure clean digital transitions.
• Key Matrix Diodes: If your application requires detecting multiple simultaneous key presses (multi-key rollover), place small signal diodes (e.g., 1N4148) in series with each push-button switch across the SEG/KS and KEY lines to prevent "phantom" key triggers.
• Ground Routing on PCB: Connect both VSS pins (Pin 8 and Pin 25) directly to a solid ground plane to ensure stable return currents during peak segment conduction.

Datasheet