Analog Devices Inc. LTC1272-3ACSW

Overview

LTC1272-3ACSW from Analog Devices (formerly Linear Technology) is a 12-bit, 3 µs successive approximation ADC with integrated sample-and-hold and on-chip 2.42 V reference. It operates from a single 5 V supply, delivers up to 250 kHz sampling rate, and maintains ±0.5 LSB differential linearity. It serves as a drop-in replacement for AD7572 in high-speed data acquisition systems requiring unipolar 0 V to 5 V input range and minimal external components.

For engineers reviewing the LTC1272-3ACSW datasheet, LTC1272-3ACSW pinout, LTC1272-3ACSW application, or LTC1272-3ACSW equivalent, this page provides verified technical context, real-world timing constraints (e.g., 1 µs minimum inter-conversion delay), confirmed dynamic performance (72 dB S/(N+D) at 10 kHz), package-specific thermal data (θ_JA = 130 °C/W), and validated alternatives for 12-bit SAR ADC migration paths.

Technical Context

The LTC1272-3ACSW implements a switched-capacitor SAR architecture with internal 12-bit capacitive DAC and comparator-based bit decision logic synchronized to CLK IN edges. Conversion begins on CS/RD falling edge and completes in exactly 13 clock cycles (f_CLK = 4 MHz), with aperture jitter <50 ps enabling accurate high-frequency signal capture.

Its dual-mode digital interface supports parallel 12-bit reads (HBEN = LOW) or two-byte 8-bit bus transfers (HBEN = HIGH), while the on-chip 2.42 V ±1% bandgap reference-curvature-corrected and trimmed-feeds both DAC and external decoupling (10 µF + 0.1 µF). The NC pin (Pin 23) confirms no negative supply requirement, distinguishing it from AD7572's dual-supply design.

Key Specifications

Pinout & Package

Package: 24-lead plastic SO wide (SW), 0.300" body width, JEDEC MS-013 variant. Thermal resistance θ_JA = 130 °C/W; suitable for reflow soldering per IPC/JEDEC J-STD-020.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7572KNZ, LTC1272-3ACSW eliminates negative supply and adds S/H, reducing system complexity; versus ADS7822U, it retains parallel bus flexibility and higher DC accuracy (±0.5 LSB DNL vs ±1 LSB), but lacks SPI convenience.

Availability

LTC1272-3ACSW is available at Aetrix Electronics and suitable for high-speed data acquisition, DSP front-end, multiplexed sensor systems, and single-supply industrial PLC modules requiring stable component supply across extended production lifecycles.

Supply support for LTC1272-3ACSW 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. (ADI) is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies.

The LTC1272-3ACSW belongs to ADI's legacy Linear Technology precision data conversion product line, engineered for high-speed, low-power, single-supply 12-bit SAR ADC applications in industrial and instrumentation systems.

FAQ

What is the maximum sampling rate supported by the LTC1272-3ACSW?

The LTC1272-3ACSW supports a maximum sustained sampling rate of 250 kHz, achieved with its 3 µs conversion time and 4 MHz clock. This rate is validated under conditions of 0 V to 5 V input, VDD = 5 V, and proper clock synchronization-ensuring the device meets its 72 dB S/(N+D) specification at 10 kHz input frequency. The LTC1272-3ACSW achieves this without pipeline architecture, relying solely on successive approximation timing.

Can the LTC1272-3ACSW replace an AD7572 in an existing design without PCB changes?

Yes, the LTC1272-3ACSW has identical pinout and footprint to the AD7572, enabling socket-level replacement. However, two modifications are required: reverse the polarity of the VREF bypass capacitor (due to +2.42 V vs –5.25 V reference), and leave Pin 23 (NC) unconnected instead of applying –15 V. The LTC1272-3ACSW also requires only 1 µs inter-conversion delay versus AD7572's longer minimum, improving throughput.

What is the purpose of the HBEN pin on the LTC1272-3ACSW?

The HBEN (High Byte Enable) pin on the LTC1272-3ACSW controls data bus multiplexing: when LOW, all 12 bits (DB11–DB0) appear on D11–D0/8 for parallel read; when HIGH, only DB11–DB8 appear on D3/11–D0/8, allowing 8-bit microprocessors to read the result in two cycles. HBEN = HIGH also disables conversion initiation, providing hardware-level control over sampling timing in the LTC1272-3ACSW.

Does the LTC1272-3ACSW require an external clock source?

No-the LTC1272-3ACSW supports both external clock input (TTL/CMOS-compatible, 4 MHz for -3 grade) and internal crystal oscillator mode. A crystal or ceramic resonator can be connected between CLK IN (Pin 17) and CLK OUT (Pin 18) to generate the required 4 MHz clock autonomously. For best analog performance, external clocks must be synchronized to RD/CS edges with ≥40 ns separation to minimize feedthrough in the LTC1272-3ACSW.

What is the thermal performance of the LTC1272-3ACSW in its SO wide package?

The LTC1272-3ACSW in the 24-lead plastic SO wide (SW) package has a junction-to-ambient thermal resistance (θ_JA) of 130 °C/W, measured per JEDEC JESD51-7. At 75 mW typical power dissipation and 25 °C ambient, this yields ~9.75 °C junction rise-well within its 110 °C T_JMAX. Layout best practices (wide copper pours, thermal vias under exposed pad if present) are recommended to maintain long-term reliability in industrial environments for the LTC1272-3ACSW.