NXP Semiconductors MC145028P

Overview

MC145028P from Motorola is a CMOS 9-bit trinary address decoder IC used in remote control encoder/decoder systems. It decodes all nine input lines as address bits (19,683 possible codes with trinary encoding), operates from 4.5 V to 18 V, features internal RC oscillator support, and outputs a Valid Transmission (VT) signal only after two consecutive matching address words are received. It is commonly deployed in infrared, RF, and ultrasonic remote control transceivers.

For engineers reviewing the MC145028P datasheet, MC145028P pinout, MC145028P application, or MC145028P equivalent, key selection considerations include its 9-bit trinary address resolution, VT output timing behavior, R1/C1 and R2/C2 external timing component requirements, supply voltage range (4.5–18 V), and compatibility with MC145026P encoder pairs in security-critical remote systems.

Technical Context

The MC145028P implements a 9-bit shift register and address comparator architecture that validates incoming serial data against locally configured address pins (A1–A9). It requires two identical address words transmitted consecutively - with no intervening data bits - before asserting VT high, enhancing transmission security against noise or spurious pulses.

Timing is governed by external R1/C1 (for pulse width discrimination) and R2/C2 (for word and transmission end detection) networks referenced to the encoder's clock frequency. Its internal power-on reset forces all outputs low at startup, ensuring deterministic initial state without external circuitry.

Key Specifications

Pinout & Package

MC145028P is housed in a 16-pin plastic DIP (Dual In-line Package), Case 648, with 0.3-inch body width and 0.1-inch lead pitch. Pin 1 is top-left corner when notch faces up.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar address decoder applications.

Compared with SC41344P and MC145027P, the MC145028P offers the highest address density (19,683 codes) and simplest VT-only interface, making it optimal for dedicated secure address gating in 4.5–18 V remote receivers where data payload is unnecessary.

Availability

MC145028P is available at Aetrix Electronics and suitable for infrared remote control receivers, RF garage door openers, ultrasonic appliance controllers, and industrial wireless sensor node receivers requiring stable component supply and long-term obsolescence management.

Supply support for MC145028P 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) is a pioneer in analog and mixed-signal IC design, known for robust, industry-standard logic and interface products.

The MC14502x family was designed specifically for low-cost, high-reliability remote control systems - emphasizing hardware-based security, minimal external components, and wide supply voltage operation.

FAQ

What is the primary function of the MC145028P in a remote control system?

The MC145028P functions exclusively as a 9-bit trinary address decoder. It receives serial data from an encoder like the MC145026P, compares all nine address bits against locally configured inputs (A1–A9), and asserts the VT output only after two identical address words are received consecutively. Unlike MC145027P, it provides no data outputs - its sole purpose is secure address validation.

Does the MC145028P require an external crystal or resonator?

No, the MC145028P does not require an external crystal or resonator. It relies entirely on external RC timing components - R1/C1 for pulse discrimination and R2/C2 for word and transmission end detection - referenced to the encoder's oscillator frequency. This eliminates timing component cost and board space while maintaining reliable decoding across temperature and voltage.

What supply voltage range is supported by the MC145028P?

The MC145028P operates over a supply voltage range of 4.5 V to 18 V. This wide range supports both standard 5 V logic systems and higher-voltage industrial or automotive remote receivers. It is not rated for operation below 4.5 V - for low-voltage applications (e.g., 3 V), SC41344P is the designated alternative.

How does the VT output behave on the MC145028P?

The VT output on the MC145028P goes high only after two complete, identical address words are received consecutively. It remains high until either a mismatch occurs in subsequent reception or no valid signal is detected for four data periods. VT is internally reset low on power-up due to the device's built-in power-on reset circuit - no external reset is needed.

Can the MC145028P decode binary-encoded addresses?

Yes, the MC145028P supports binary encoding on its A1–A9 inputs, yielding 512 possible addresses (2⁹). However, its full capability - 19,683 addresses - is realized only with trinary (low/high/open) encoding. Binary mode sacrifices address space but simplifies switch design and eliminates ambiguity in open-circuit detection logic.