STMicroelectronics M5451QT

Overview

M5451QT from STMicroelectronics is a 35-output LED display driver IC with 15mA sink capability per output, integrated current generators eliminating external resistors, continuous brightness control via analog voltage input (pin 19), and serial data interface (DATA IN/CLOCK IN). It operates across 4.75–13.2V supply, supports TTL-compatible logic, and drives alphanumeric displays in non-multiplexed direct-drive mode for instrumentation readouts.

For engineers reviewing the M5451QT datasheet, M5451QT pinout, M5451QT application, or M5451QT equivalent, key selection considerations include its 35-bit static latch architecture, internal 400Ω brightness reference resistor, 0.5MHz max clock frequency, 34-segment safe operating area at 85°C, and PLCC44 package thermal profile.

Technical Context

The M5451QT implements a 35-bit static master-slave shift register followed by parallel latches, synchronized by a 36-bit frame (1 start bit + 35 data bits) that auto-generates LOAD and RESET signals on clock edges. Its brightness control uses an internal current mirror with 20× gain relative to pin 19 input current, enabling analog dimming without external DACs.

All 35 outputs are open-drain N-channel MOSFETs with guaranteed 15mA sink at VO = 1V and IB = 750µA, ±20% output matching, and off-state leakage <10µA. The device features power-on reset, no external load signal requirement, and operates over –25°C to +85°C ambient temperature range.

Key Specifications

Pinout & Package

The M5451QT is housed in a 44-pin Plastic Leaded Chip Carrier (PLCC44) package with gull-wing leads, 1.27mm pitch, and 17.4mm × 16.51mm body size. Pin 1 is marked by a corner notch; seating plane coplanarity ≤0.101mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LED display driver applications.

Compared with MAX7219CNG and TLC59283DBQR, the M5451QT uniquely delivers static 35-bit direct drive with analog brightness control in a single PLCC44 package - simplifying design for fixed-format alphanumeric displays where scan artifacts or complex firmware are unacceptable.

Availability

M5451QT is available at Aetrix Electronics and suitable for industrial instrumentation readouts, microprocessor-based display systems, and relay status indicators requiring stable component supply and long-term obsolescence management.

Supply support for M5451QT includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in power management, microcontrollers, analog ICs, and automotive-grade components.

The M5451QT belongs to ST's legacy LED display driver product line, designed specifically for cost-sensitive, high-reliability industrial and consumer display applications requiring minimal external components and robust thermal performance.

FAQ

What is the maximum number of LED segments that can be safely driven simultaneously at 85°C ambient?

At Tamb = 85°C, Figure 7 shows the M5451QT supports up to 34 segments at 15mA each when VO = 1V, based on its 560mW total package power dissipation limit and 124°C/W thermal resistance. Exceeding this risks junction temperature exceeding 150°C, triggering thermal shutdown or accelerated aging.

Can the M5451QT drive common-anode LED displays?

No - the M5451QT provides only sink outputs (N-channel open-drain), so it is designed exclusively for common-anode LED configurations where LEDs connect anode to VDD and cathode to output pins. Driving common-cathode displays would require external high-side switches or level-shifting circuitry not supported by the IC.

Is a capacitor required on the brightness control pin (pin 19)?

Yes - a 1nF capacitor must be connected between pin 19 and VSS to suppress high-frequency oscillations caused by parasitic inductance in the brightness control loop. Omitting this capacitor may result in unstable output current and visible LED flicker, especially under varying load conditions.

Does the M5451QT support daisy-chaining multiple devices?

No - the M5451QT has no dedicated serial output pin; its DATA IN is input-only. Daisy-chaining requires cascading shift registers, which this device lacks. To drive more than 35 segments, separate DATA/CLOCK lines must be used for each IC, or a microcontroller must manage parallel data loading across multiple units.