Analog Devices Inc. LTC1272-8ACSW#PBF

Overview

LTC1272-8ACSW#PBF from Analog Devices (formerly Linear Technology) is a 12-bit, 8 µs conversion time, single-supply sampling analog-to-digital converter with on-chip sample-and-hold and internal 2.42 V reference. It operates from a 5 V supply only, delivers up to 111 kHz sampling rate, and maintains ±1 LSB integral linearity over 0°C to 70°C - used in high-speed data acquisition systems requiring compact, low-power ADCs with minimal external components.

For engineers reviewing the LTC1272-8ACSW#PBF datasheet, LTC1272-8ACSW#PBF pinout, LTC1272-8ACSW#PBF application, or LTC1272-8ACSW#PBF equivalent, this page provides verified technical context, real-world timing constraints (e.g., 1 µs minimum inter-conversion delay), package-specific thermal data (θ_JA = 130°C/W), and validated drop-in alternatives for AD7572-based designs.

Technical Context

The LTC1272-8ACSW#PBF implements a successive approximation register (SAR) architecture with a switched-capacitor DAC and integrated sample-and-hold. Its 12-bit resolution is achieved via binary-weighted capacitor array switching synchronized to an external or crystal-based clock (1.6 MHz nominal for -8 variant).

It features dual digital interface modes: parallel 12-bit read (HBEN = LOW) or two-byte 8-bit bus access (HBEN = HIGH), with BUSY output signaling conversion status. The device uses separate analog (AGND) and digital (DGND) ground pins and requires strict PCB layout separation to maintain 72 dB S/(N+D) at 10 kHz input.

Key Specifications

Pinout & Package

Package: 24-lead plastic SO wide (SW), 0.300-inch body width, RoHS-compliant lead-free finish (PBF). Thermal resistance θ_JA = 130°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 12-bit SAR ADC applications.

Compared with AD7572KNZ, LTC1272-8ACSW#PBF reduces conversion time by 33%, eliminates negative supply, and integrates S/H and reference - enabling smaller, cooler, lower-BOM designs. Versus ADS7822U, it trades serial simplicity for higher resolution, parallel speed, and self-contained analog subsystem.

Availability

LTC1272-8ACSW#PBF is available at Aetrix Electronics and suitable for industrial data acquisition, DSP front-end, single-supply instrumentation, and legacy system upgrade applications requiring stable component supply and long-term obsolescence management.

Supply support for LTC1272-8ACSW#PBF 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

Analog Devices, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors for precision and high-speed applications.

The LTC1272 family was designed by Linear Technology to deliver pin-compatible, enhanced-performance replacements for industry-standard ADCs like the AD7572 - targeting data acquisition, instrumentation, and embedded control systems demanding speed, integration, and supply simplicity.

FAQ

What is the maximum sampling rate achievable with the LTC1272-8ACSW#PBF?

The LTC1272-8ACSW#PBF achieves a maximum sustained sampling rate of 111 kHz, determined by its 8 µs conversion time plus the 1 µs minimum inter-conversion delay (t11). This rate assumes optimal timing synchronization between CLK IN and RD/CS edges, with ≥40 ns separation to suppress clock feedthrough. At this rate, the device maintains 72 dB S/(N+D) for 10 kHz input signals.

Can the LTC1272-8ACSW#PBF directly replace the AD7572 in an existing PCB layout?

Yes, the LTC1272-8ACSW#PBF is pin-compatible with the AD7572 and fits the same 24-lead SO wide footprint. However, successful drop-in replacement requires reversing the polarity of the VREF bypass capacitor (due to +2.42 V vs –5.25 V reference) and leaving Pin 23 (NC) unconnected instead of applying –15 V. No PCB changes are needed beyond these two modifications.

Does the LTC1272-8ACSW#PBF require an external clock source, or can it operate with a crystal?

The LTC1272-8ACSW#PBF supports both configurations: a 1.6 MHz crystal or ceramic resonator may be connected between CLK IN (Pin 17) and CLK OUT (Pin 18), or an external TTL/CMOS clock signal may be applied to CLK IN alone. The internal oscillator is optimized for 1.6 MHz operation in the -8 variant; duty cycle is non-critical for external clocks, and CLK OUT provides an inverted copy for system timing distribution.

How does the HBEN pin affect data output behavior on the LTC1272-8ACSW#PBF?

When HBEN = LOW, the LTC1272-8ACSW#PBF outputs the full 12-bit conversion result across D11–D0/8 simultaneously. When HBEN = HIGH, it multiplexes: D11–D8 carry the upper 4 bits (DB11–DB8), while D7–D0/8 carry the lower 8 bits (DB7–DB0) - enabling two sequential 8-bit reads. This mode is essential for interfacing with 8-bit microcontrollers lacking 12-bit data buses.

What is the purpose of the NC pin (Pin 23) on the LTC1272-8ACSW#PBF?

Pin 23 is Not Connected internally on the LTC1272-8ACSW#PBF. It exists solely to match the AD7572's pinout - where it serves as the –15 V negative supply input. On the LTC1272-8ACSW#PBF, this pin must remain unconnected or tied to ground; applying any voltage to it has no functional effect and risks violating absolute maximum ratings if >6 V is applied.