NXP Semiconductors MC14489BP

Overview

MC14489BP from Motorola is a CMOS multi-character LED display and lamp driver IC with synchronous serial interface, 24-bit display register, 8-bit configuration register, and on-chip 7-segment decoder. It drives up to 5-digit common-cathode displays (with decimals), 4½-digit displays with sign, or 25 discrete lamps via five bank-switched cathode outputs and eight anode current sources. It operates from 4.5 V to 5.5 V and supports -40°C to +130°C junction temperature.

For engineers reviewing the MC14489BP datasheet, MC14489BP pinout, MC14489BP application, or MC14489BP equivalent, this page provides verified technical context including BitGrabber™ register architecture, multiplexed-by-5 scanning, single-resistor current setting (Rx), brightness control via D23 bit, and compatibility with Motorola SPI and National Semiconductor MICROWIRE™ serial protocols.

Technical Context

The MC14489BP implements a 24½-stage static shift register with Schmitt-triggered Data In/Clock/Enable inputs, enabling DC-to-4 MHz serial clock operation. Its patented BitGrabber™ registers allow random-access updates to display or configuration registers without address bits-24-bit transfers update display data, 8-bit transfers modify configuration.

Internally, it integrates a 7-segment ROM decoder (supporting 0–9, A–F, 15 letters/symbols), five independent low-R_ON (≤10 Ω) FET bank switches (320 mA sink per bank), and eight matched anode current sources (up to 35 mA each, set by external Rx resistor). Refresh rate is fixed at 700–1900 Hz with 20% duty cycle for optimal LED brightness and EMI suppression.

Key Specifications

Pinout & Package

MC14489BP is housed in a 20-pin plastic dual-in-line package (PDIP), Case 73B, with 0.3-inch body width and 0.1-inch lead pitch. Thermal resistance is 90°C/W (junction-to-ambient, natural convection).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX7219CNG and TM1637, the MC14489BP offers broader configurability (5-digit + decimals, 4½-digit + sign, or 25 lamps), wider operating temperature (–40°C to +130°C), superior EMI management, and true register retention down to 3.0 V-making it uniquely suited for ruggedized embedded instrumentation.

Availability

MC14489BP is available at Aetrix Electronics and suitable for industrial panel meters, automotive instrument clusters, medical equipment displays, and test & measurement instruments requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MC14489BP 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

Motorola Semiconductor (now part of NXP Semiconductors) pioneered high-reliability analog and mixed-signal ICs for industrial, automotive, and communications markets.

The MC14489B product line was designed specifically for embedded LED display systems requiring integrated decoding, multiplexing, and robust serial control-targeting applications where MCU resources are constrained and environmental resilience is critical.

FAQ

What is the maximum number of digits the MC14489BP can drive in a single-device configuration?

The MC14489BP can drive up to 5 digits plus decimals in a single-device configuration. This is achieved using its five bank outputs (Bank 1–5) and eight anode drivers (a–h), where a–g drive segments and h drives decimal points. The device also supports 4½-digit displays with sign or 25 discrete lamps-configurable via the 8-bit configuration register. All modes retain full brightness control and register data down to 3.0 V supply.

Does the MC14489BP require external current-limiting resistors for each LED segment?

No, the MC14489BP does not require external per-segment current-limiting resistors. It uses a single external resistor (Rx, connected between Pin 8 and VSS) to set the peak anode drive current for all eight outputs (a–h). When D23 = high, peak current is ~13–17.5 mA (at 5.0 V, Rx = 2.0 kΩ); when D23 = low, current is reduced ~50%. This architecture eliminates 35+ discrete resistors in a 5-digit display design.

How does the MC14489BP handle power-up sequencing to prevent display glitches?

The MC14489BP incorporates a dedicated power-on reset (POR) circuit that blanks the display at power-up regardless of VDD ramp rate. To ensure reliable operation, the Clock pin must remain stable (not floated or toggled) until VDD reaches ≥3 V. If Clock control during power-up is impractical, the POR can be overridden by writing C0 = 1 to the configuration register after initialization-ensuring deterministic startup behavior for the MC14489BP in all embedded systems.

Can multiple MC14489BP devices be cascaded, and what is the serial protocol overhead?

Yes, up to six MC14489BP devices can be cascaded using the Data Out (Pin 18) to Data In (Pin 12) daisy-chain connection. For N devices, configuration register access requires 8N clock cycles and display register access requires 24N cycles-no additional address or steering bits needed due to BitGrabber™ architecture. Table 2 in the datasheet defines exact byte counts and leading "don't care" bytes based on N modulo 4, ensuring deterministic firmware implementation for the MC14489BP cascade.

What thermal considerations apply when driving high-current LEDs with the MC14489BP?

When driving high-current LEDs, thermal design must account for total power dissipation: PT = PD + PI, where PD = (iOH)(N)(VDD – VLED)(B/5) and PI = (1.5 mA)(VDD) + IRx(VDD – IRxRx). For a worst-case 5-digit display (8 anodes, 5 banks, iOH = 20 mA, VDD = 5.25 V, VLED = 1.8 V), PD ≈ 552 mW. With RθJA = 90°C/W (PDIP), ΔT = 50°C-so maximum ambient must be ≤79°C to keep TJ ≤130°C. Use ≥1% tolerance Rx and avoid Rx < 700 Ω without heatsinking for the MC14489BP.