Analog Devices Inc. LTC1540IS8#PBF

Overview

LTC1540IS8#PBF from Analog Devices (formerly Linear Technology) is an ultralow-power nanopower comparator with integrated 1.182V ±2% voltage reference, designed for battery-critical monitoring functions. It delivers 0.68µA typical supply current at –40°C to +85°C, supports 2V–11V single-supply operation, features TTL/CMOS-compatible output sourcing up to 40mA, and enables adjustable hysteresis via external resistors - ideal for low-battery detection in portable medical devices.

For engineers reviewing the LTC1540IS8#PBF datasheet, LTC1540IS8#PBF pinout, LTC1540IS8#PBF application, or LTC1540IS8#PBF equivalent, key selection considerations include its guaranteed sub-1µA quiescent current over industrial temperature range, REF pin capability to drive 0.01µF bypass capacitors without oscillation, input common-mode range extending to V–, and compatibility with threshold detector, window comparator, and oscillator circuit topologies.

Technical Context

The LTC1540IS8#PBF integrates a precision bandgap reference and rail-to-rail input comparator in a single SO-8 package, with independent V– and GND pins enabling true split-supply operation (±1V to ±5.5V) or robust single-supply use. Its HYST pin accepts a voltage between REF – 50mV and REF to program hysteresis, and the output stage eliminates crowbar current during transitions to prevent supply glitches.

Input leakage is ±0.01nA (typ) at 25°C, offset voltage is ±15mV (max) over temperature, and propagation delay is 70µs (typ) with 10mV overdrive. The reference maintains ±2.5mV load regulation when sourcing up to 100µA or sinking up to 10µA, and operates stably with capacitive loads up to 0.01µF directly on the REF pin.

Key Specifications

Pinout & Package

Package: 8-lead plastic SO (S8), 0.150-inch narrow body, RoHS-compliant lead-free finish (PBF).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nanopower comparator with reference applications.

Compared with LTC1540IS8#PBF, LTC1440CS8#PBF offers tighter reference accuracy but lacks hysteresis control and REF drive strength, while MAX921ESA+ trades off quiescent current and integrated functionality for open-drain flexibility - making LTC1540IS8#PBF optimal for self-contained, low-noise, capacitor-driven threshold detection.

Availability

LTC1540IS8#PBF is available at Aetrix Electronics and suitable for battery-powered system monitoring, threshold detectors, window comparators, and oscillator circuits requiring stable component supply across industrial temperature ranges.

Supply support for LTC1540IS8#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. (acquired Linear Technology in 2017) designs high-performance analog, mixed-signal, and digital signal processing components for precision instrumentation, power management, and signal conditioning.

The LTC1540 product line delivers nanopower signal-conditioning solutions for energy-constrained applications including portable medical devices, wireless sensors, and battery-backed systems where microampere-level supply current and integrated reference stability are critical.

FAQ

What is the maximum capacitive load the REF pin of LTC1540IS8#PBF can drive without oscillation?

The REF pin of LTC1540IS8#PBF can drive up to 0.01µF directly without oscillation, as confirmed in the Applications Information section. For larger capacitors (up to 10µF), a series damping resistor is required - Figure 1 in the datasheet provides the recommended resistance values versus capacitance. This capability eliminates the need for external reference buffers in space-constrained designs.

Does LTC1540IS8#PBF support true dual-supply operation, and what are the voltage limits?

Yes, LTC1540IS8#PBF supports true dual-supply operation from ±1V to ±5.5V, with V+ and V– pins accepting independent potentials. Absolute maximum ratings allow V+ to V– differential up to 12V, and input pins tolerate voltages from (V– – 0.3V) to (V+ + 0.3V). This architecture enables rail-to-rail input operation even with asymmetric supplies, unlike many comparators limited to single-supply biasing.

How is hysteresis programmed on LTC1540IS8#PBF, and what is the maximum achievable band?

Hysteresis on LTC1540IS8#PBF is programmed by applying a voltage between REF – 50mV and REF to the HYST pin using two external resistors - one from REF to HYST, another from HYST to V–. The resulting hysteresis voltage band equals twice the REF–HYST voltage difference, with a maximum of 100mV. The band tolerance is ±15%, and hysteresis is disabled by shorting HYST to REF.

What is the guaranteed supply current specification for LTC1540IS8#PBF over its full operating temperature range?

LTC1540IS8#PBF guarantees a maximum supply current of 0.71µA over the full –40°C to +85°C industrial temperature range, with 0.68µA typical. This value is measured under defined conditions (IN– – IN+ = 80mV, HYST = REF) and appears in the Electrical Characteristics table under "ICC Supply Current" with "l" notation indicating full-temperature coverage.

Can LTC1540IS8#PBF drive logic inputs directly, and what output voltage levels does it deliver?

Yes, LTC1540IS8#PBF delivers TTL/CMOS-compatible output levels: VOH = V+ – 0.4V (min) at –8mA sink, VOL = GND + 0.4V (max) at 0.8mA source. Its rail-to-rail CMOS output swings fully from GND to V+, enabling direct interfacing with 3.3V or 5V logic families without level shifters - and it sustains 40mA continuous source current for driving LEDs or small MOSFET gates.