Analog Devices Inc. LTC2955CDDB-1

Overview

LTC2955CDDB-1 from Analog Devices (formerly Linear Technology) is a micropower pushbutton on/off controller with automatic turn-on via voltage monitoring, designed for system power management in battery-powered and automotive applications. It features 1.2µA supply current, ±36V robust PB input, 1.5V–36V VIN range, and active-high EN output optimized for DC/DC converter shutdown control. Used in portable instruments and GPS devices to enable graceful microprocessor shutdown.

For engineers reviewing the LTC2955CDDB-1 datasheet, LTC2955CDDB-1 pinout, LTC2955CDDB-1 application, or LTC2955CDDB-1 equivalent, key selection considerations include its DFN-10 package, 0°C to 70°C operating range, EN polarity (LTC2955-1), TMR-configurable forced turn-off timing, and compatibility with low-leakage regulator control interfaces.

Technical Context

The LTC2955CDDB-1 implements a dual-input power control architecture: debounced pushbutton (PB) and monitored voltage (ON) inputs feed into independent edge-triggered logic paths. Its internal LDO (~5.2V) powers the EN pull-up and provides margin for regulator SHUTDOWN pins.

It integrates configurable blanking timers-512ms KILL turn-on blanking and 1s EN lockout-to ensure stable regulator power-up/down sequencing and prevent spurious re-triggering. The TMR pin supports external capacitor-based extension of forced turn-off duration up to ~17ms per 1nF.

Key Specifications

Pinout & Package

Package: 10-Lead (3mm × 2mm) Plastic DFN with optional exposed pad (Pin 11) connected to GND.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar pushbutton power control applications.

Compared with TPS3808G33 and LTC2954CDDB-1, the LTC2955CDDB-1 uniquely integrates pushbutton debouncing, interrupt signaling, source-differentiating PGD, and configurable forced turn-off - making it the only option supporting full user-initiated and supply-triggered power sequencing with µP coordination in a single DFN-10 device.

Availability

LTC2955CDDB-1 is available at Aetrix Electronics and suitable for portable instrumentation, automotive telematics, and industrial data loggers requiring stable component supply with long-term lifecycle assurance.

Supply support for LTC2955CDDB-1 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 maintains its precision analog and power management product lines with full datasheet, simulation model, and application support.

The LTC2955 family is designed for intelligent power sequencing in battery-constrained and harsh-environment systems, emphasizing ultra-low quiescent current, high-voltage robustness, and deterministic timing for µP-coordinated shutdown.

FAQ

What is the EN output behavior of the LTC2955CDDB-1 during power-up?

At power-up, the LTC2955CDDB-1 asserts EN high after a 1-second lockout period if the ON pin is already above 0.8V. If ON is low, EN remains low until a rising edge occurs on ON or a valid PB press is detected. This ensures regulated output has stabilized before enabling downstream circuitry, preventing brown-out conditions in the LTC2955CDDB-1's own supply chain.

How does the SEL pin affect operation of the LTC2955CDDB-1?

The SEL pin on the LTC2955CDDB-1 enables or disables ON pin falling-edge detection for automatic turn-off. When SEL is tied to VIN (>0.8V), a falling edge on ON initiates turn-off (DFN-only feature); when tied to GND, only rising edges trigger turn-on. This allows flexible power policy configuration without firmware changes - critical for field-deployed devices where ON may represent AC presence or battery voltage.

Can the LTC2955CDDB-1 drive a P-channel MOSFET directly?

No - the LTC2955CDDB-1 is the -1 variant with active-high EN output optimized for driving regulator SHUTDOWN pins. To drive a P-channel MOSFET gate, use the LTC2955CDDB-2, which provides active-low EN with internal 900kΩ pull-up to VIN. Substituting LTC2955CDDB-1 would require an external inverter or level-shifter, adding complexity and leakage risk.

What is the minimum KILL pulse width required to release EN on the LTC2955CDDB-1?

The LTC2955CDDB-1 requires a KILL signal low for at least 60µs to reliably release the EN output. This short minimum width ensures responsiveness to µP-generated shutdown commands while rejecting noise spikes. For robust implementation, firmware should hold KILL low for ≥200µs to accommodate propagation delays and ensure deterministic behavior across temperature and voltage corners.

How is the TMR capacitor value calculated for a desired forced turn-off delay on the LTC2955CDDB-1?

Use CTMR = 0.19 × tTMR (in µF/sec), where tTMR is the additional delay beyond the base 64ms. For example, to achieve 1s total forced turn-off time: tTMR = 1000ms − 64ms = 936ms → CTMR = 0.19 × 0.936 ≈ 0.178µF. Standard 0.18µF capacitor yields ~1.01s total delay. The LTC2955CDDB-1's TMR pin must be decoupled to GND with this capacitor; leaving it open defaults to 64ms.