Analog Devices Inc. LTC2905CDDB#TRPBF

Overview

LTC2905CDDB#TRPBF from Analog Devices (formerly Linear Technology) is a precision dual supply monitor IC with pin-selectable thresholds and adjustable reset timeout. It monitors two independent voltage rails (e.g., 5V/3.3V, 3.3V/1.2V), provides ±1.5% threshold accuracy over 0°C to 70°C, features open-drain RST output guaranteed functional down to 1V input, and uses an external capacitor on TMR pin to set reset delay (e.g., 200ms with 22nF). It is used in embedded power sequencing for desktop computers and network servers.

For engineers reviewing the LTC2905CDDB#TRPBF datasheet, LTC2905CDDB#TRPBF pinout, LTC2905CDDB#TRPBF application, or LTC2905CDDB#TRPBF equivalent, key selection criteria include its adjustable reset timeout via TMR capacitor, nine programmable V1/V2 threshold combinations, 5%/7.5%/10% tolerance selection, DFN-8 package compatibility, and guaranteed RST operation with V1 ≥ 1V or V2 ≥ 1V.

Technical Context

The LTC2905CDDB#TRPBF implements a dual-input comparator architecture with internal bandgap reference and three-state programming pins (S1, S2, TOL) that configure both voltage thresholds and tolerance without external resistors. Its reset pulse generator uses an external capacitor on the TMR pin to set timeout - 9 ms/nF scaling enables precise timing control from ~200 μs (open) to seconds (large capacitors).

It features glitch immunity via integrated low-pass filtering at comparator outputs and a retriggerable timer that resets on any threshold violation during timeout. The internal VCC is auto-selected as the greater of V1 or V2, enabling operation even when only one rail is present above 1V, and guarantees correct RST logic state across full temperature range.

Key Specifications

Pinout & Package

Package: 8-lead plastic DFN (3 mm × 2 mm), exposed pad (Pin 9) soldered to PCB ground for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3808G33DBVR and MAX6816EUT+T, the LTC2905CDDB#TRPBF offers uniquely configurable thresholds, ±1.5% accuracy, and capacitor-adjustable reset timing - critical for multi-voltage systems requiring design reuse across product variants.

Availability

LTC2905CDDB#TRPBF is available at Aetrix Electronics and suitable for desktop computers, network servers, and handheld devices requiring stable component supply, long-term production continuity, and RoHS-compliant packaging.

Supply support for LTC2905CDDB#TRPBF 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) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.

The LTC2905 belongs to Linear's precision power monitoring product line, designed specifically for reliable, low-power, multi-rail voltage supervision in computing, communications, and industrial systems where deterministic reset behavior is critical.

FAQ

What is the operating temperature range for the LTC2905CDDB#TRPBF?

The LTC2905CDDB#TRPBF is rated for 0°C to 70°C ambient operation. This commercial-grade temperature range is specified in the ordering information table and applies to the DDB package variant with #TRPBF tape-and-reel packaging. It is distinct from the I-grade (–40°C to 85°C) and H-grade (–40°C to 125°C) versions, which carry different part number suffixes.

How do I configure the LTC2905CDDB#TRPBF to monitor 5V and 3.3V supplies with 5% tolerance?

To configure the LTC2905CDDB#TRPBF for 5V/3.3V monitoring with 5% tolerance, connect S1 and S2 to V1 (i.e., tie to Pin 8), and connect TOL to V1. This matches the first row of Table 1 and Table 2 in the datasheet. The device will then assert RST if either supply falls below 4.675V (5V × 95%) or 3.086V (3.3V × 95%), with ±1.5% accuracy over temperature.

What capacitor value gives a 200ms reset timeout on the LTC2905CDDB#TRPBF?

A 22 nF capacitor connected between the TMR pin (Pin 2) and GND yields a nominal 200 ms reset timeout for the LTC2905CDDB#TRPBF. This follows the device's 9 ms/nF scaling factor: 22 nF × 9 ms/nF = 198 ms ≈ 200 ms. Standard 22 nF film or ceramic capacitors with low leakage (<2.1 μA) are recommended.

Does the LTC2905CDDB#TRPBF require external pull-up resistors on the RST pin?

The LTC2905CDDB#TRPBF includes a weak internal pull-up to VCC on the RST pin (~6 μA), so external pull-ups are optional. They are recommended only when faster rise time (<10 μs) or VOH > VCC is needed. For standard microprocessor reset inputs, the internal pull-up suffices; a 10 kΩ external resistor reduces rise time from ~86 μs to ~3.3 μs with 150 pF load.

Can the LTC2905CDDB#TRPBF monitor supplies below 1.0V?

No - the LTC2905CDDB#TRPBF does not support monitoring supplies below 1.0V. Its V2 input is specified for 1.0V, 1.2V, 1.5V, 1.8V, 2.5V, or 3.3V; the lowest programmable V2 threshold is 1.0V with 10% tolerance (0.900V min). Operation with V1 or V2 < 1.0V violates Absolute Maximum Ratings and invalidates RST output guarantee.