Texas Instruments LM1269NA/NOPB

Overview

LM1269NA/NOPB from Texas Instruments (formerly National Semiconductor) is a 110 MHz I²C-compatible RGB video preamplifier IC designed for CRT monitor front-end signal conditioning. It integrates three-channel video amplification, on-chip OSD mixing, four 8-bit external DACs for brightness/bias control, and ABL (Auto Beam Limit) interface - all in a single 24-pin DIP package. It targets low-cost 14″–17″ bus-controlled monitors with OSD capability and 1024×768 @70 Hz resolution.

For engineers reviewing the LM1269NA/NOPB datasheet, LM1269NA/NOPB pinout, LM1269NA/NOPB application, or LM1269NA/NOPB equivalent, this page delivers verified technical context, exact pin functions, real-world timing and gain specifications, confirmed CRT system integration roles, and validated alternative options for legacy monitor design continuity.

Technical Context

The LM1269NA/NOPB implements a fully integrated CMOS video signal path with independent 7-bit contrast, gain, and DC offset registers per channel, controlled via I²C (slave address 0xDCh write / 0xDDh read). Its black-level clamping operates directly on AC-coupled inputs using internal high-impedance (20 MΩ) buffers and programmable clamp pulse timing, eliminating external clamp capacitors.

It features hardware-synchronized horizontal blanking derived from H Flyback analog input (pin 24), with precise 50 ns propagation delay, and supports Power Save Mode (bit 1 of register 9) reducing supply current from 225 mA to 60 mA - an 80% reduction - by disabling output stages while retaining I²C control and reference stability.

Key Specifications

Pinout & Package

LM1269NA/NOPB is housed in a 24-lead molded plastic DIP package (NS package code N24D), compatible with standard through-hole mounting and wave soldering. Pin spacing is 0.3 inch (7.62 mm), body width 0.6 inch (15.24 mm).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar RGB video preamplifier applications.

Compared with LM1269NA/NOPB, LM1268NA/NOPB removes OSD functionality to reduce cost and complexity, while LM1267NA/NOPB preserves full feature parity but shifts I²C addressing - making it suitable for multi-preamp topologies where bus arbitration is required.

Availability

LM1269NA/NOPB is available at Aetrix Electronics and suitable for legacy CRT monitor manufacturing, industrial display refurbishment, medical imaging console support, and educational electronics labs requiring stable component supply and long-term obsolescence management.

Supply support for LM1269NA/NOPB 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

Texas Instruments acquired National Semiconductor in 2011 and maintains full documentation, packaging, and quality compliance for legacy linear products including the LM126x family.

The LM1269NA/NOPB belongs to TI's CRT video interface product line, engineered specifically for cost-sensitive, high-reliability analog monitor systems requiring integrated video amplification, OSD compositing, and beam-current safety controls.

FAQ

What is the function of pin 10 (VrefRext) on the LM1269NA/NOPB?

Pin 10 (VrefRext) sets the internal current sources for the LM1269NA/NOPB's reference circuitry using an external 10 kΩ 1% resistor. This resistor determines the accuracy and temperature stability of the internal VRef (1.25–1.55 V), which feeds the DACs, contrast/gain stages, and OSD mixer. Layout sensitivity is extreme - any noise or coupling near pin 10 degrades video black-level stability and introduces visible banding.

Does the LM1269NA/NOPB support true drop-in replacement for LM1203-based designs?

The LM1269NA/NOPB is not a drop-in replacement for the LM1203 due to fundamental architectural differences: LM1203 is a triple op-amp without I²C, DACs, OSD, or ABL. However, LM1269NA/NOPB can replace LM1203-based designs when the PCB is modified to accommodate its 24-pin DIP footprint, add I²C pull-ups, route H Flyback/Clamp signals, and reassign DAC outputs to cathode bias networks - enabling full digital control where analog trimming was previously required.

How does the Power Save Mode operate in the LM1269NA/NOPB?

The LM1269NA/NOPB implements two-tier Power Save Mode via register 9: setting bit-0 blanks all video outputs (reducing beam current), while setting bit-1 disables the output buffer stage entirely - dropping supply current from 225 mA to 60 mA. Both modes retain full I²C accessibility and VRef stability, allowing rapid wake-up without recalibration. The 80% power reduction directly lowers neck board temperature and extends CRT heater life.

What is the maximum horizontal scan frequency supported by the LM1269NA/NOPB's H Flyback input?

The LM1269NA/NOPB's H Flyback input (pin 24) is designed for standard CRT horizontal frequencies up to 100 kHz, with guaranteed 200 ns clamp pulse width at 15 kHz line rate. At higher frequencies (e.g., 96 kHz for 1280×1024), the internal blanking timing remains accurate, but external RC filtering (e.g., 56 pF capacitor as shown in Figure 5) becomes critical to suppress ringing and ensure clean edge detection - otherwise blanking jitter or incomplete blanking may occur.

Can the LM1269NA/NOPB DAC outputs drive CRT cathode bias directly?

Yes - the LM1269NA/NOPB's DAC1–DAC3 outputs (pins 16–14) are specified for 0.5–4.2 V operation and designed to interface directly with LM2479/LM2480 cathode clamp ICs or discrete G1 bias networks. DAC4 (pin 13) modulates DAC1–3 in brightness-control mode, enabling unified cathode voltage adjustment. Load current must remain below 100 µA per DAC to maintain ±50 mV/V VCC sensitivity and ±0.5 mV/°C temperature drift.