Analog Devices Inc. LTC1285CN8#PBF

Overview

LTC1285CN8#PBF from Analog Devices (formerly Linear Technology) is a 12-bit micropower successive approximation ADC with differential analog inputs, single-supply operation (2.7V–6V), 160µA typical supply current at 7.5ksps, auto-shutdown to 1nA, and on-chip sample-and-hold - designed for battery-operated sensor interfaces and isolated data acquisition systems.

For engineers reviewing the LTC1285CN8#PBF datasheet, LTC1285CN8#PBF pinout, LTC1285CN8#PBF application, or LTC1285CN8#PBF equivalent, this page delivers verified specifications, SO-8 package terminal mapping, real-world use cases in low-power ratiometric sensing, and two confirmed alternative parts with documented functional and interface differences.

Technical Context

The LTC1285CN8#PBF implements a switched-capacitor SAR architecture with internal reference buffering and rail-to-rail compatible digital I/O. Its differential input stage supports common-mode voltages up to VCC and allows direct connection to transducers without gain stages.

It uses a 3-wire SPI/Microwire-compatible serial interface (CS/CLK/DOUT), requires no configuration word, and outputs MSB-first 12-bit data after one null bit. Conversion timing is fixed at 12 clock cycles (100µs at 120kHz), with sampling initiated by CS falling edge.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (SO-8, N8), 150°C max junction temperature, θJA = 130°C/W.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ADS7822U and MAX1113EUA+, the LTC1285CN8#PBF uniquely combines differential input, external VREF support, and sub-200µA active current - making it optimal for precision, low-power, ratiometric sensor systems where signal integrity and battery longevity are critical.

Availability

LTC1285CN8#PBF is available at Aetrix Electronics and suitable for battery-operated systems, remote data acquisition, and isolated data acquisition requiring stable component supply and long-term manufacturability.

Supply support for LTC1285CN8#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 (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and DSP ICs for precision measurement and signal conditioning.

The LTC1285CN8#PBF belongs to Linear's legacy micropower ADC family, engineered specifically for ultra-low-power, high-resolution data acquisition in portable and remote instrumentation.

FAQ

What is the maximum clock frequency supported by the LTC1285CN8#PBF?

The LTC1285CN8#PBF supports up to 120kHz clock frequency when operating from a 3V supply. At 2.7V, the maximum recommended clock is 120kHz; it increases slightly with higher supply voltage - e.g., up to 200kHz at 6V - per the "Maximum Clock Frequency vs Supply Voltage" curve in the datasheet. Exceeding these limits risks conversion errors due to insufficient internal settling time.

Does the LTC1285CN8#PBF require an external reference voltage?

Yes, the LTC1285CN8#PBF requires an external reference voltage applied to Pin 1 (VREF). It does not include an internal reference. The reference can be derived from a precision voltage reference IC, a filtered LDO output, or the supply rail itself - enabling ratiometric operation with resistive sensors. VREF range is 1.5V to VCC, supporting flexible system-level scaling.

Can the LTC1285CN8#PBF interface directly with a 5V microcontroller?

Yes, the LTC1285CN8#PBF digital I/O (CS, CLK, DOUT) is specified for 3V operation but tolerant to 5V logic levels: VIH = 2.0V min at VCC = 3.6V, and VOH = 2.4V min at VCC = 2.7V with 10µA load. For reliable 5V MCU interfacing, use level-shifting on CS/CLK inputs or ensure MCU GPIOs are 3.3V-tolerant; DOUT may require a pull-up to 3.3V if driving 5V inputs.

How does the auto-shutdown feature work in the LTC1285CN8#PBF?

The LTC1285CN8#PBF automatically enters ultra-low-power shutdown (1nA typical) whenever CS/SHDN (Pin 5) is held high. During active conversion, it draws 160µA typical. Even if CS remains low after data transfer, internal bias circuits power down after conversion completion - minimizing current between samples. This behavior is intrinsic and requires no software control.

Is the LTC1285CN8#PBF pin-compatible with the LTC1288CN8#PBF?

No, the LTC1285CN8#PBF and LTC1288CN8#PBF are not pin-compatible. The LTC1285CN8#PBF uses Pins 1–4 for VREF, +IN, –IN, GND; the LTC1288CN8#PBF uses Pins 1–4 for CS/SHDN, CH0, CH1, GND. Their pin functions differ fundamentally due to distinct architectures (differential vs. dual-channel MUX), so PCB layout and firmware must be redesigned for substitution.