Analog Devices Inc. LTC2911IDDB-4

Overview

LTC2911IDDB-4 from Analog Devices (formerly Linear Technology) is a precision triple supply monitor IC with power-fail comparator and latched reset functionality, designed for systems requiring high-accuracy voltage supervision of 3.3V, 1.2V, and an adjustable rail. It features ±1.5% threshold accuracy over –40°C to 85°C, 30µA typical quiescent current, and internal 200ms reset timeout - used in industrial control, network infrastructure, and automotive electronics for reliable power sequencing and early brownout warning.

For engineers reviewing the LTC2911IDDB-4 datasheet, LTC2911IDDB-4 pinout, LTC2911IDDB-4 application, or LTC2911IDDB-4 equivalent, key selection criteria include its fixed 3.3V/1.2V dual-supply monitoring configuration, PFI-based power-fail signaling with 500mV falling threshold, TMR-controlled latch mode for margin testing, and DFN-8 (3mm × 2mm) package compatibility with space-constrained PCB layouts.

Technical Context

The LTC2911IDDB-4 implements three independent comparators: V1 monitors 3.3V at –6.5% (3.086V), V2 monitors 1.2V at –6.5% (1.122V), and ADJ monitors an external rail via resistive divider with 500mV nominal threshold. All comparators maintain ±1.5% accuracy across temperature and include glitch filtering for noise immunity.

Its power-fail path uses PFI input with 500mV falling / 515mV rising thresholds (3% hysteresis) to drive PFO low for early warning; RST asserts low if any monitored rail falls below its threshold and remains low until all rails exceed thresholds for ≥200ms (internal timeout). TMR pin supports latch mode (GND pull) and timeout selection (V1 tie).

Key Specifications

Pinout & Package

Package: 8-lead (3mm × 2mm) plastic DFN with exposed pad (Pin 9, GND). RoHS-compliant, lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326–33D2+T and TPS3808G33DBVR, the LTC2911IDDB-4 uniquely integrates triple-rail monitoring, PFI-based early warning, and latch-mode margin testing in a compact DFN package - delivering higher integration density and more deterministic fault response for complex multi-rail systems.

Availability

LTC2911IDDB-4 is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and medical device applications requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.

Supply support for LTC2911IDDB-4 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 technologies, serving industrial, automotive, communications, and healthcare markets.

The LTC2911 family was developed by Linear Technology (acquired by ADI in 2017) to address demand for ultra-accurate, low-power supply monitoring in space-constrained, thermally demanding applications - emphasizing ±1.5% threshold stability and robust glitch immunity.

FAQ

What is the exact reset threshold voltage for the V2 pin on the LTC2911IDDB-4?

The V2 pin on the LTC2911IDDB-4 has a guaranteed reset threshold of 1.122V (–6.5% of 1.2V) with ±1.5% accuracy over –40°C to +85°C, meaning the actual trip point falls between 1.104V and 1.140V. This value is factory-trimmed and specified in the Electrical Characteristics table under VRT12 parameter. The LTC2911IDDB-4 is specifically configured for 1.2V monitoring, distinguishing it from other variants like LTC2911IDDB-3 (1.8V) or LTC2911IDDB-2 (2.5V).

How does the PFI input on the LTC2911IDDB-4 differ from the ADJ input in terms of hysteresis and use case?

The PFI input on the LTC2911IDDB-4 features 15mV typical hysteresis (500mV falling / 515mV rising) optimized for early power-fail detection with noise rejection, while the ADJ input has no inherent hysteresis and is intended for precise adjustable-rail monitoring via external resistor divider. PFI drives the PFO output directly for system-level warning; ADJ feeds the RST generator. Both share the same 500mV nominal threshold but serve distinct fault-response roles in the LTC2911IDDB-4 architecture.

Can the LTC2911IDDB-4 operate with VCC below 1V, and what happens to RST/PFO outputs?

Yes, the LTC2911IDDB-4 guarantees RST and PFO functionality down to VCC = 0.5V, enabling clean reset assertion during deep brownout. Below 1V, the outputs remain fully operational: RST pulls low if any monitored rail fails, and PFO pulls low on PFI undervoltage. Output low voltage stays ≤0.15V at 5µA sink current even at VCC = 0.5V, ensuring unambiguous logic levels for downstream controllers. This behavior is explicitly characterized in the VOL specification.

What is the recommended capacitor value for external reset timeout on the LTC2911IDDB-4's TMR pin?

The LTC2911IDDB-4 supports external timeout via capacitor from TMR to GND, with CTMR ≈ tRST × 106.5 pF/ms. For example, a 20ms timeout requires ~2.13nF (standard 2.2nF ceramic). Leakage must be <500nA; X7R or C0G dielectrics are preferred. Leaving TMR open yields ~400µs timeout (parasitic-dependent), while tying to V1 activates the internal 200ms timer - eliminating capacitor need entirely. The LTC2911IDDB-4 datasheet Figure 5 provides exact CTMR vs. tRST curves.

Does the LTC2911IDDB-4 require separate bypass capacitors on both V1 and V2 pins?

Yes, the LTC2911IDDB-4 requires ≥0.1µF ceramic bypass capacitors from V1 to GND and V2 to GND. V1 bypassing is mandatory for stable internal regulation; V2 bypassing is required per datasheet Note 4 for LTC2911-1 through LTC2911-4 variants (including LTC2911IDDB-4) to suppress noise coupling and ensure accurate threshold detection. These capacitors must be placed adjacent to their respective pins with short traces to minimize inductance - critical for maintaining ±1.5% accuracy under dynamic load conditions.