Analog Devices Inc. LTC1326IS8#PBF

Overview

LTC1326IS8#PBF from Analog Devices (formerly Linear Technology) is a micropower precision triple supply monitor IC designed for systems requiring simultaneous monitoring of 2.5V, 3.3V, and an adjustable supply. It delivers ±0.75% threshold accuracy, 20µA typical supply current, 200ms internal reset delay, active-low/open-drain RST and SRST outputs, and manual push-button reset functionality - enabling reliable power-on, brownout, and user-initiated reset in portable and embedded computing.

For engineers reviewing the LTC1326IS8#PBF datasheet, LTC1326IS8#PBF pinout, LTC1326IS8#PBF application, or LTC1326IS8#PBF equivalent, key selection considerations include its guaranteed reset assertion down to VCC3 ≥ 1V or VCC25 ≥ 1V, glitch-immune comparators with 13µs response time, dual-mode reset (200ms hard / 100µs soft), and compatibility with SO-8 packaging for space-constrained industrial and battery-powered designs.

Technical Context

The LTC1326IS8#PBF implements three independent high-accuracy voltage comparators - one each for VCC25 (2.5V nominal), VCC3 (3.3V nominal), and VCCA (adjustable, 1.000V threshold) - with internal 200ms reset timer and PBR-triggered state machine. Its power-detect/gate-drive architecture selects the highest valid supply (VCC3 or VCC25) to drive the RST output FET, ensuring correct logic state even during asymmetric power-up sequences.

Reset generation is synchronized across all monitored rails: RST remains asserted until all three supplies exceed their respective thresholds (VRT25 = 2.363V, VRT3 = 3.118V, VRTA = 1.000V) for ≥200ms. The PBR input enables two distinct reset modes - sub-2-second assertion yields a 100µs SRST pulse; ≥2-second assertion forces RST low for 200ms post-release - with built-in 20–35ms debounce.

Key Specifications

Pinout & Package

Package: 8-Lead Plastic SO (Small Outline, Narrow 0.150") - RoHS-compliant, surface-mount, JEDEC MS-012AC compliant, θJA = 150°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar triple supply monitoring applications.

Compared with LTC1726-2.5 and LTC2903, the LTC1326IS8#PBF uniquely combines micropower operation (20µA), integrated push-button reset with dual-mode output (RST/SRST), and guaranteed 1V minimum supply operation - making it optimal for portable systems requiring both robust brownout protection and user-initiated soft reset capability.

Availability

LTC1326IS8#PBF is available at Aetrix Electronics and suitable for desktop computers, notebook computers, and intelligent instruments requiring stable component supply with guaranteed long-term availability and traceable sourcing.

Supply support for LTC1326IS8#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 and continues to manufacture and support its precision analog and power management portfolio.

The LTC1326 series belongs to Linear's micropower supply monitoring product line, engineered specifically for reliable, low-current supervision of multi-rail systems in portable, embedded, and industrial applications where power efficiency and reset integrity are critical.

FAQ

What is the operating temperature range for the LTC1326IS8#PBF?

The LTC1326IS8#PBF is rated for –40°C to +85°C industrial temperature operation. This range is confirmed by Absolute Maximum Ratings and Electrical Characteristics tables specifying performance across –40°C ≤ TA ≤ 85°C, including ±0.75% threshold accuracy and 20µA supply current stability. The device uses the SO-8 package with θJA = 150°C/W, supporting reliable thermal performance in enclosed industrial enclosures.

Does the LTC1326IS8#PBF support monitoring of a 5V supply?

No - the LTC1326IS8#PBF is the -2.5 variant and monitors VCC25 (2.5V), VCC3 (3.3V), and VCCA (adjustable 1.0V). The 5V-monitoring version is the LTC1326IS8#PBF's sibling part LTC1326IS8#PBF (no suffix or "-2.5"), which substitutes VCC5 (4.725V threshold) for VCC25. Pin compatibility exists between variants, but threshold sets are mutually exclusive and not interchangeable.

Can the LTC1326IS8#PBF generate a reset when only one supply is out of regulation?

Yes - the LTC1326IS8#PBF asserts RST whenever any one of the three monitored supplies (VCC25, VCC3, or VCCA) falls below its respective threshold (2.363V, 3.118V, or 1.000V), and holds RST low until all three supplies remain above threshold for ≥200ms. This behavior is explicitly documented in the Applications Information section under "Supply Monitoring" and verified in the Block Diagram and Timing Diagrams.

What is the purpose of the VCCA pin on the LTC1326IS8#PBF?

The VCCA pin on the LTC1326IS8#PBF is a high-impedance input with a fixed 1.000V threshold comparator, intended for monitoring adjustable supplies (e.g., DC/DC feedback dividers) or serving as a logic-level detector. Its trip point is guaranteed at 1.000V (±0.75%) across temperature, and it draws only ±15nA input current - enabling direct connection to sensitive analog nodes without loading.

How does the push-button reset function differ between soft and hard reset modes on the LTC1326IS8#PBF?

The LTC1326IS8#PBF distinguishes soft vs hard reset based on PBR assertion duration: a <2-second press generates a 100µs SRST pulse (preserving DRAM refresh), while ≥2-second press forces RST low for 200ms post-release (full system reset). This dual-mode behavior is implemented via an internal timer and debounce counter, with documented tPB = 2.0s typical and tSRST = 100µs typical - eliminating need for external timing components.