Analog Devices Inc. LTC1197IS8#PBF

Overview

LTC1197IS8#PBF from Analog Devices (formerly Linear Technology) is a 10-bit, 250ksps successive approximation ADC with differential analog input, internal sample-and-hold, and SPI/MICROWIRE-compatible 3-wire serial interface. It operates from a single 2.7V supply, draws only 0.8mA typical supply current at full speed, and features auto shutdown that scales power linearly with sampling rate. It is used in portable instrumentation for high-resolution DC-coupled signal acquisition.

For engineers reviewing the LTC1197IS8#PBF datasheet, LTC1197IS8#PBF pinout, LTC1197IS8#PBF application, or LTC1197IS8#PBF equivalent, key selection criteria include guaranteed 10-bit no-missing-codes resolution, ±2 LSB offset error over temperature, 2.7V operation with external VREF, differential input range up to 2.7V, and MSOP-8 package compatibility with space-constrained PCB layouts.

Technical Context

The LTC1197IS8#PBF implements a switched-capacitor SAR architecture with integrated sample-and-hold. Its differential input stage accepts signals referenced to GND or floating common-mode voltages, supporting ratiometric measurements when paired with an external reference on VREF.

It uses a synchronous 3-wire serial interface (CS, CLK, DOUT) with MSB-first output and fixed 14-clock-cycle timing: 1.5 clocks for sampling, 10.5 for conversion, and 2 null bits before data. No configuration word is required-conversion initiates on CS fall, eliminating software overhead.

Key Specifications

Pinout & Package

Package: 8-pin MSOP (3mm × 3mm, 0.65mm pitch), RoHS-compliant, moisture sensitivity level 1.

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 LTC1197IS8#PBF uniquely combines guaranteed differential input, external VREF flexibility, and sub-1mA 2.7V operation in an 8-pin MSOP-making it optimal for ultra-low-power, precision differential sensing where board area and supply headroom are constrained.

Availability

LTC1197IS8#PBF is available at Aetrix Electronics and suitable for portable medical devices, industrial process transmitters, energy harvesting nodes, and test equipment requiring stable component supply with guaranteed long-term availability.

Supply support for LTC1197IS8#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 semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC1197 series belongs to ADI's precision data acquisition product line, designed specifically for low-power, high-accuracy DC and low-frequency AC measurement in size- and energy-constrained systems.

FAQ

What is the maximum clock frequency supported by the LTC1197IS8#PBF?

The LTC1197IS8#PBF supports a maximum clock frequency of 3.5MHz when operating from a 2.7V supply. This corresponds to its rated 250ksps sampling rate. Exceeding this frequency may cause timing violations, increased INL error, or conversion failure. The device's tCYC (total cycle time) is specified at 14 clock cycles, so 3.5MHz yields a minimum conversion period of 4µs-matching the 250ksps specification. Always maintain proper setup/hold times (tsuCS = 78ns, thCS = 40ns) per the datasheet.

Does the LTC1197IS8#PBF require an external reference voltage?

Yes, the LTC1197IS8#PBF requires an external reference voltage applied to the VREF pin. It does not include an internal reference. The VREF pin accepts voltages from 0.2V to VCC + 0.05V (i.e., up to 4.05V at VCC = 4V), enabling flexible full-scale scaling-for example, 2.5V yields 244µV/LSB resolution. The reference must be low-noise and well-bypassed (1µF recommended) to maintain specified offset and gain accuracy. Ratiometric operation is supported when VREF is derived from the same source as the sensor excitation.

Can the LTC1197IS8#PBF interface directly with a microcontroller GPIO without level-shifting?

Yes, the LTC1197IS8#PBF is fully compatible with 2.7V–4V microcontrollers. Its digital inputs (CS, CLK) meet CMOS thresholds: VIH ≥ 1.9V and VIL ≤ 0.45V at VCC = 2.7V. Its DOUT output drives VOH ≥ 2.3V and VOL ≤ 0.3V under 400µA load-fully interoperable with same-supply MCUs. No level-shifting is needed. However, ensure the MCU's GPIO can tolerate 2.7V logic levels and that clock rise/fall times stay within 10–40ns (per tr/tf specs) to avoid metastability.

What is the operating temperature range of the LTC1197IS8#PBF?

The LTC1197IS8#PBF is specified for operation from –45°C to +85°C (I-grade). This extended industrial temperature range is confirmed in the Absolute Maximum Ratings and Recommended Operating Conditions tables. All key specifications-including offset error (±2 LSB), INL (±1 LSB), and sampling rate (250ksps)-are guaranteed across this full range. The part uses the "I" suffix in its ordering code (LTC1197IS8#PBF) to denote this grade, making it suitable for under-hood automotive, outdoor industrial, and aerospace-adjacent applications.

How does the auto shutdown feature of the LTC1197IS8#PBF reduce system power consumption?

The LTC1197IS8#PBF automatically enters low-power shutdown whenever CS is high, drawing only leakage current (~1µA typical). During active conversion, supply current scales linearly with sampling frequency-from 0.8mA at 250ksps down to ~1µA at 1Hz. This eliminates software-controlled sleep modes or external enable circuitry. For example, a system sampling at 1ksps draws ~3.2µA average current, extending battery life dramatically versus always-on ADCs. The transition is seamless: CS high → immediate shutdown; CS low → instant wake and conversion start.