Analog Devices Inc. LTC1197LCS8#PBF

Overview

LTC1197LCS8#PBF from Analog Devices (acquired Linear Technology) is a 10-bit, 250ksps successive approximation ADC with differential analog input, internal sample-and-hold, and 3-wire SPI/MICROWIRE-compatible serial interface. It operates from a single 2.7V supply, draws only 0.8mA typical at full speed, and features auto shutdown that scales supply current linearly with sampling frequency. It is used in portable instrumentation for high-resolution signal digitization of low-voltage sensor outputs.

For engineers reviewing the LTC1197LCS8#PBF datasheet, LTC1197LCS8#PBF pinout, LTC1197LCS8#PBF application, or LTC1197LCS8#PBF equivalent, key selection criteria include its 2.7V operation, 10-bit no-missing-codes resolution, differential input range (0V to VCC), 2.2mW power dissipation, and MSOP-8 package compatibility with space-constrained embedded systems.

Technical Context

The LTC1197LCS8#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold, supporting unipolar conversion only. Its differential input accepts signals referenced to GND with common-mode voltage up to VCC, enabling direct connection to low-output-impedance sensors without gain stages.

It uses a 3-wire serial interface (CS, CLK, DOUT) with MSB-first output, requiring no configuration word. Conversion is initiated by CS falling edge; data appears after two null bits, synchronized to rising CLK edges. Power management is fully automatic-no software control needed for shutdown between conversions.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (MS8), 3mm × 3mm, 0.65mm pitch, exposed pad not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit SAR ADC applications.

Compared with ADS7822U and MAX11100ETE+, the LTC1197LCS8#PBF uniquely combines differential input, external reference support, auto shutdown, and MSOP-8 packaging - making it optimal for compact, battery-sensitive designs requiring noise-immune analog acquisition without layout or firmware overhead.

Availability

LTC1197LCS8#PBF is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered sensor nodes, and industrial transmitters requiring stable component supply, long-lifecycle assurance, and RoHS-compliant sourcing.

Supply support for LTC1197LCS8#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.

The LTC1197LCS8#PBF belongs to ADI's legacy Linear Technology precision data acquisition product line, designed specifically for ultra-low-power, high-resolution ADC applications in space- and energy-constrained embedded systems.

FAQ

What is the maximum clock frequency supported by the LTC1197LCS8#PBF?

The LTC1197LCS8#PBF supports a maximum clock frequency of 3.5MHz when operating from a 2.7V supply. This clock rate enables its full 250ksps sampling capability. Exceeding this frequency may cause timing violations or conversion errors, especially at lower supply voltages. The device's tCYC (total cycle time) is specified as 14–16 clock cycles, and timing parameters like tdDO and tCONV are validated only up to 3.5MHz under recommended conditions.

Does the LTC1197LCS8#PBF require an external reference voltage?

Yes, the LTC1197LCS8#PBF requires an external reference voltage applied to the VREF pin. It does not include an internal reference. The reference range is 0.2V to VCC + 0.05V, allowing flexible full-scale settings - for example, 2.5V for high-precision ratiometric measurements or 1.0V for low-voltage sensor interfaces. The VREF pin must be bypassed with a 1µF ceramic capacitor to ensure stable conversion accuracy.

Can the LTC1197LCS8#PBF interface directly with a microcontroller SPI peripheral?

Yes, the LTC1197LCS8#PBF is SPI and MICROWIRE compatible and interfaces directly with standard microcontroller SPI peripherals without glue logic. It uses a 3-wire interface (CS, CLK, DOUT) with MSB-first, rising-edge-clocked data output. No DIN line is required, simplifying routing. The LTC1197LCS8#PBF does not drive MISO actively during CS high - ensuring clean bus sharing in multi-device SPI configurations.

What is the analog input impedance of the LTC1197LCS8#PBF?

The LTC1197LCS8#PBF has an analog input capacitance of 20pF on the active channel (+IN or –IN) and 5pF on the inactive channel. Its DC input leakage current is ±1µA over temperature. This high-impedance, capacitive input enables direct connection to high-Z sources like thermopiles or piezoelectric sensors - though external RC filtering (e.g., 10Ω + 1nF) is recommended to limit charge injection and settle within the 1.5-clock sampling window.

How does auto shutdown work on the LTC1197LCS8#PBF?

Auto shutdown on the LTC1197LCS8#PBF is fully hardware-controlled and requires no software command. When CS is held high, the device enters shutdown mode and draws only leakage current (~3µA). During active conversion, supply current scales linearly with sampling frequency - e.g., 0.8mA at 250ksps, ~80µA at 25ksps. This behavior is intrinsic to the internal biasing and clock-gating architecture, eliminating firmware complexity for power optimization.