Analog Devices Inc. LTC1272-8CCN

Overview

LTC1272-8CCN 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. It serves as a drop-in replacement for AD7572 in unipolar data acquisition systems requiring fast, accurate digitization of 0 V to 5 V analog signals.

For engineers reviewing the LTC1272-8CCN datasheet, LTC1272-8CCN pinout, LTC1272-8CCN application, or LTC1272-8CCN 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), and validated alternatives for legacy AD7572-based designs.

Technical Context

The LTC1272-8CCN uses LTBiCMOS switched-capacitor architecture to integrate a 12-bit successive approximation register (SAR) ADC, precision sample-and-hold, and curvature-corrected bandgap reference. Its conversion cycle comprises a sample phase (charge acquisition on CSAMPLE) followed by a convert phase (binary-weighted DAC comparison under CLK control).

It supports two digital interface modes: Slow Memory Mode (conversion start and data read synchronized) and ROM Mode (read returns prior result). Clock synchronization requires ≥40 ns separation between RD/CS falling edge and nearest CLK IN edge to suppress clock feedthrough-critical for maintaining 72 dB S/(N+D) at 250 kHz sampling (LTC1272-3) or 111 kHz (LTC1272-8).

Key Specifications

Pinout & Package

Package: 24-lead narrow plastic DIP (PDIP), 0.300" width, JEDEC MS-001, operating temperature range 0°C to 70°C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with AD7572KNZ, LTC1272-8CCN eliminates negative supply and adds sample-and-hold, reducing system complexity; compared with LTC1273-8CN, it trades 2 dB S/(N+D) and 1 LSB offset for cost-sensitive volume production where ±4 LSB gain error is acceptable.

Availability

LTC1272-8CCN is available at Aetrix Electronics and suitable for high-speed data acquisition, DSP front-end interfaces, and multiplexed sensor systems requiring stable component supply across industrial temperature ranges.

Supply support for LTC1272-8CCN 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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, acquired Linear Technology in 2017.

The LTC1272 family was designed by Linear Technology specifically for pin-compatible upgrades of AD7572-based systems, emphasizing single-supply operation, integrated reference, and fast acquisition in compact DIP/SO packages.

FAQ

What is the maximum sampling rate supported by the LTC1272-8CCN?

The LTC1272-8CCN supports a maximum sampling rate of 111 kHz, determined by its 8 µs conversion time and 1 µs minimum inter-conversion delay. This rate is achieved using a 1.6 MHz clock input and is specified for operation across the full 0°C to 70°C temperature range. At this rate, the device maintains 72 dB S/(N+D) for a 10 kHz input signal, enabling accurate digitization of bandwidth-limited analog waveforms in real-time systems.

Can the LTC1272-8CCN replace an AD7572 in an existing PCB layout?

Yes, the LTC1272-8CCN is pin-compatible with the AD7572 and fits into the same 24-lead PDIP socket. However, successful replacement requires reversing the polarity of the VREF bypass capacitor (10 µF tantalum) and omitting the 10 Ω series resistor used with AD7572's –5.25 V reference. Pin 23 (NC on LTC1272-8CCN) remains unconnected, and no PCB changes are needed beyond these passive component adjustments.

Does the LTC1272-8CCN require an external clock source?

No, the LTC1272-8CCN does not require an external clock source. It supports both configurations: an external 1.6 MHz TTL/CMOS clock applied to CLK IN (Pin 17), or a 1.6 MHz crystal/ceramic resonator connected between CLK IN and CLK OUT (Pins 17 and 18). The internal oscillator eliminates the need for external timing components in self-contained designs, while the external clock option provides flexibility for system-level clock synchronization.

What is the purpose of the HBEN pin on the LTC1272-8CCN?

The HBEN (High Byte Enable) pin on the LTC1272-8CCN controls data bus configuration and conversion enable. When HBEN is LOW, all 12 data outputs (D11–D0/8) present the full conversion result. When HBEN is HIGH, only D11–D8 output the four most significant bits, while D3/11–D0/8 repeat those same MSBs-enabling 8-bit microprocessor interfacing. Critically, HBEN HIGH also disables conversion initiation, providing hardware-level conversion gating.

How is the reference voltage used internally in the LTC1272-8CCN?

The 2.42 V reference generated at Pin 2 (VREF) is used internally to bias the 12-bit capacitive DAC and define the full-scale input range of 0 V to 5 V. It is curvature-corrected and factory-trimmed to ±1% accuracy with 25 ppm/°C tempco. Externally, it can source up to 1 mA for auxiliary circuitry, but must be decoupled with a 10 µF tantalum capacitor in parallel with a 0.1 µF ceramic capacitor to maintain low-noise operation and prevent code transition errors in the LTC1272-8CCN.