Analog Devices Inc. LTC2308IUF#PBF

Overview

LTC2308IUF#PBF from Analog Devices (formerly Linear Technology) is a low-noise, 500ksps, 8-channel, 12-bit successive approximation register (SAR) ADC with integrated 2.5V reference, 8-channel analog multiplexer, and SPI/MICROWIRE-compatible serial interface. It operates from a single 5V supply, draws 3.5mA at full rate, and supports software-selectable unipolar (0V–4.096V) or bipolar (±2.048V) input ranges - ideal for precision industrial data acquisition systems requiring high channel density and low power.

For engineers reviewing the LTC2308IUF#PBF datasheet, LTC2308IUF#PBF pinout, LTC2308IUF#PBF application, or LTC2308IUF#PBF equivalent, key selection criteria include guaranteed no missing codes, 73.3dB SINAD at 1kHz, internal conversion clock enabling SCK up to 40MHz, auto-shutdown scaling current from 3.5mA to 200µA, and QFN-24 (4mm × 4mm) package with exposed thermal pad.

Technical Context

The LTC2308IUF#PBF implements a fully differential sample-and-hold circuit with 70dB common-mode rejection, supporting both single-ended and differential input configurations via 6-bit SPI command word (S/D, O/S, S1, S0, UNI, SLP). Its internal 12-bit capacitive DAC uses charge redistribution and a binary-search SAR algorithm synchronized to a factory-trimmed internal clock (t_CONV = 1.3–1.6µs).

It features separate OVDD (2.7–5.25V) for level-shifted digital outputs, internal 2.5V bandgap reference (±25ppm/°C tempco), and buffered 4.096V REFCOMP output - all bypassed via specified capacitor networks (2.2µF VREF, 10µF + 0.1µF REFCOMP). Channel-to-channel isolation exceeds –109dB at 1kHz.

Key Specifications

Pinout & Package

Package: 24-pin 4mm × 4mm plastic QFN (UF) with exposed thermal pad (Pin 25), rated for –40°C to +85°C operating temperature.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC2308IUF#PBF, ADS8688IPWR offers higher resolution at the cost of increased power and loss of bipolar input flexibility, while MAX11131ETL+ provides extended temperature operation but sacrifices dynamic performance and input range versatility.

Availability

LTC2308IUF#PBF is available at Aetrix Electronics and suitable for industrial process control, motor control feedback, and battery-powered instrumentation requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LTC2308IUF#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 LTC2308IUF#PBF belongs to ADI's precision data acquisition product line, designed specifically for high-channel-density, low-power, and noise-sensitive applications such as portable test equipment and distributed sensor networks.

FAQ

What is the operating temperature range of the LTC2308IUF#PBF?

The LTC2308IUF#PBF is rated for –40°C to +85°C operation, making it suitable for industrial environments with wide ambient temperature swings. This grade is explicitly designated by the "I" suffix in the part number and confirmed in the Absolute Maximum Ratings table. All electrical specifications - including SINAD, INL, and supply current - are guaranteed across this full range when AVDD, DVDD, and OVDD are maintained within 4.75V–5.25V, 4.75V–5.25V, and 2.7V–5.25V respectively.

Does the LTC2308IUF#PBF support differential input configurations?

Yes, the LTC2308IUF#PBF supports differential inputs via its configurable analog multiplexer: CH0–CH1, CH2–CH3, CH4–CH5, and CH6–CH7 form four independent differential pairs. Configuration is controlled by the 6-bit SPI command word (S/D and O/S bits), allowing per-conversion selection. The fully differential sample-and-hold circuit provides 70dB common-mode rejection, and channel-to-channel isolation exceeds –109dB at 1kHz - critical for rejecting noise in high-gain sensor interfaces.

How does the auto-shutdown feature work on the LTC2308IUF#PBF?

The LTC2308IUF#PBF auto-shutdown feature dynamically scales supply current based on sample rate: it draws 3.5mA at 500ksps, 180µA at 1ksps (Nap Mode), and 7µA in Sleep Mode. This is achieved internally without external control signals - the device detects idle time between conversions and transitions states automatically. No firmware intervention is required, simplifying power management in battery-operated systems while maintaining full 12-bit performance upon wake-up.

Can the internal reference of the LTC2308IUF#PBF be overdriven with an external source?

Yes, the LTC2308IUF#PBF supports two external reference modes: (1) Overdriving VREF (Pin 7) with a precision 2.5V source improves initial accuracy and temperature drift; (2) Grounding VREF and driving REFCOMP (Pin 8) with an external 1–5V reference disables the internal buffer and sets full-scale range directly. Both methods are documented in the Applications Information section and require appropriate decoupling per the datasheet layout guidelines.

What is the minimum acquisition time required for accurate 12-bit conversion on the LTC2308IUF#PBF?

The LTC2308IUF#PBF requires a minimum acquisition time (t_ACQ) of 240ns - defined as the interval from the 7th SCK rising edge to the next CONVST rising edge. This time allows the internal sample-and-hold capacitors to settle to 12-bit accuracy. The value is guaranteed across –40°C to +85°C and is independent of external source impedance when driving impedances are ≤1kΩ; higher impedances require additional settling time per the RC filter design guidelines in the datasheet.