HT1621B RAM Mapping 324 LCD Controller for I/O MCU SSOP-48

HT1621B RAM Mapping 32×4 LCD Controller for I/O MCU SSOP-48 is a high-performance, multi-functional LCD driver peripheral specifically designed to interface with microcontrollers for high-density display applications. This device features a 128-bit (32×4) RAM mapping architecture. Consequently, it allows the host MCU to easily control large-scale segmented liquid crystal displays by writing data directly to the internal memory. The HT1621B minimizes the number of necessary MCU pins by utilizing a simple 3-wire or 4-wire serial interface. Furthermore, its integrated features—such as the software-configurable bias and power-down mode—make it an exceptionally efficient choice for battery-powered instruments. Therefore, you should consider this controller for any embedded design that requires a reliable, clear, and low-power user interface.

Key Features:

• High-Density Driver: Manages up to 128 segments (32 segments and 4 commons), providing ample capacity for complex alphanumeric and icon-based displays.
• Integrated RAM Mapping: Stores display data in a 32×4 bit RAM, reducing the processing overhead required from the main microcontroller.
• Software-Configurable Logic: Allows users to select 1/2 or 1/3 bias and 1/2, 1/3, or 1/4 duty cycle via software commands for maximum display flexibility.
• Power Management: Includes a Power Down command and a Sleep Mode to significantly extend battery life in portable electronics.
• Built-in Timing Circuitry: Features an internal 256 kHz RC oscillator and a watchdog timer (WDT) to ensure system stability and timing accuracy.

Technical Specifications:

• Operating Voltage (V_DD): 2.4 V to 5.2 V
• Operating Current: Typically 150 µA at 3 V (Active Mode)
• Standby Current: ≤ 5 µA (Power Down Mode)
• Display Capacity: 32 segments × 4 commons (128 bits total)
• Interface Type: 3-wire or 4-wire serial interface (CS, RD, WR, DATA)
• Buzzer Output Frequencies: 2 kHz or 4 kHz software selectable
• Operating Temperature: −40°C to +85°C

Mechanical Specifications:

• Package Type: SSOP-48 (Shrink Small Outline Package)
• Mounting Method: Surface Mount Technology (SMT)
• Lead Finish: Tin-plated matte finish for superior solderability.
• Encapsulation: Molded plastic compound (UL 94 V-0 rated).

Dimensions:

• Body Length: ≈ 15.90 mm
• Body Width (Excluding Leads): ≈ 7.50 mm
• Total Width (Including Leads): ≈ 10.30 mm
• Lead Pitch: 0.635 mm
• Package Height: ≈ 2.65 mm max

Pinout and Wiring:

• VSS/VDD: Connect to ground and the positive supply voltage (2.4 V to 5.2 V), respectively.
• CS (Chip Select): Pull this pin low to enable the serial communication with the host MCU.
• WR/RD: Write and Read clock pins; use WR for data input and RD for reading back internal RAM.
• DATA: Bidirectional serial data line for transmitting commands and display patterns.
• COM0-COM3: Common backplane outputs that connect directly to the LCD panel.
• SEG0-SEG31: Segment driver outputs that control the individual elements of the liquid crystal display.

Datasheet Reference:

• Download Holtek HT1621B LCD Controller Datasheet

Commonly Used in:

• Digital Measuring Tools: Driving displays for multimeters, electronic scales, and digital thermometers.
• Industrial Control Panels: Providing visual feedback on small automation modules and PLCs.
• Household Appliances: Implementing the display interface on microwave ovens, washing machines, and HVAC controllers.

Applications:

• Consumer Electronics: Controls segmented LCDs in clocks, portable games, and handheld medical devices.
• Automotive Instrumentation: Powers dashboard secondary displays and trip computers.
• Telecommunications: Manages the caller ID and status screens on fixed-line telephones.

Equivalent Models:

• TM1621: A popular, functionally identical equivalent often used as a direct replacement in various display modules.
• VK1621: Another widely available variant that offers the same 32×4 RAM mapping and serial interface protocol.
• HT1622: However, note that this model supports a larger 32×8 mapping for even higher segment counts.

Package Includes:

• 1 x HT1621B RAM Mapping 32×4 LCD Controller IC (SSOP-48)