Analog Devices Inc. LTC2905CDDB#TRMPBF

Overview

LTC2905CDDB#TRMPBF from Analog Devices (formerly Linear Technology) is a precision dual-supply voltage monitor IC with pin-selectable thresholds and adjustable reset timeout. It monitors two independent supply 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, and uses an external capacitor on TMR pin to set reset delay (e.g., 200ms with 22nF). It is used in power sequencing and fault detection for embedded logic systems.

For engineers reviewing the LTC2905CDDB#TRMPBF datasheet, LTC2905CDDB#TRMPBF pinout, LTC2905CDDB#TRMPBF application, or LTC2905CDDB#TRMPBF equivalent, key selection criteria include its programmable dual-threshold architecture, guaranteed RST operation down to V1 ≥ 1V or V2 ≥ 1V, 8-lead DFN (3mm × 2mm) package, ±1.5% temperature-stable accuracy, and compatibility with automated margining and brownout recovery in space-constrained designs.

Technical Context

The LTC2905CDDB#TRMPBF implements a dual-comparator architecture with bandgap reference and resistor network decoding, enabling nine voltage combinations (e.g., 5.0V/3.3V, 3.3V/1.2V) via S1/S2 pins and three tolerance levels (5%/7.5%/10%) via TOL pin. Its internal VCC auto-selects as the greater of V1 or V2, powering both comparators and the reset pulse generator.

Reset assertion is glitch-immune due to integrated low-pass filtering at comparator outputs and a programmable timeout (tRST) controlled by CTMR on the TMR pin (9 ms/nF scaling). The RST output is open-drain with strong pull-down (40Ω typical) and weak internal pull-up (~6μA), supporting wired-OR configurations and external pull-up flexibility.

Key Specifications

Pinout & Package

Package: 8-lead plastic DFN (3mm × 2mm), exposed pad (Pin 9) soldered to PCB ground plane for thermal and electrical performance. Pin numbering follows standard DDB8 top-view orientation with Pin 1 marked by bar.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6816EUT+T and TPS3808G18DBVR, the LTC2905CDDB#TRMPBF uniquely integrates dual-rail monitoring, pin-selectable thresholds, and capacitor-tunable reset delay in a single 3mm × 2mm DFN - reducing component count, PCB area, and calibration effort in multi-voltage systems.

Availability

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

Supply support for LTC2905CDDB#TRMPBF 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 power management semiconductors.

The LTC2905CDDB#TRMPBF belongs to the LTC® precision supervisor family, designed specifically for reliable dual-supply monitoring in space-constrained, thermally demanding applications where threshold accuracy and glitch immunity are critical.

FAQ

What is the function of the TMR pin on the LTC2905CDDB#TRMPBF?

The TMR pin on the LTC2905CDDB#TRMPBF is the reset timeout programming terminal. Connecting an external capacitor (CTMR) from TMR to GND sets the reset delay time (tRST) at 9 ms/nF - for example, a 22nF capacitor yields ~200ms. Leaving TMR open results in a minimum delay of ~200μs. This pin is exclusive to the LTC2905 series and replaces the fixed 200ms RST output found on the LTC2904. The LTC2905CDDB#TRMPBF uses this feature to provide flexible reset timing without internal timing circuitry.

How does the LTC2905CDDB#TRMPBF achieve ±1.5% threshold accuracy over temperature?

The LTC2905CDDB#TRMPBF achieves ±1.5% threshold accuracy using a trimmed bandgap reference and laser-trimmed resistor network within its internal voltage divider. This architecture maintains tight ratio matching across –40°C to 125°C, and the specification applies to all nine V1/V2 combinations and three tolerance settings. Accuracy is verified per device during production test at multiple temperatures. The LTC2905CDDB#TRMPBF delivers this performance without external calibration components or software compensation.

Can the LTC2905CDDB#TRMPBF monitor asymmetric supply pairs like 3.3V and 1.2V?

Yes, the LTC2905CDDB#TRMPBF explicitly supports asymmetric supply monitoring including 3.3V/1.2V, as defined in Table 1 of its datasheet (S1 = Open, S2 = V1 configuration). V1 accepts 5V/3.3V/2.5V inputs while V2 accepts 3.3V/2.5V/1.8V/1.5V/1.2V/1.0V - enabling 18 valid combinations. The LTC2905CDDB#TRMPBF decodes these via three-state S1/S2 pins, eliminating need for external resistive dividers or multiple part numbers.

What is the minimum supply voltage required for the LTC2905CDDB#TRMPBF to assert a valid RST signal?

The LTC2905CDDB#TRMPBF guarantees correct RST logic state (VOL ≤ 0.4V at 2.5mA load) when either V1 ≥ 1V or V2 ≥ 1V. This is because the internal VCC is derived from the greater of V1 or V2, and the output driver circuitry remains functional down to 1V. Below 1V, RST behavior is undefined. This specification ensures reliable brownout detection during power-down sequences, a key capability of the LTC2905CDDB#TRMPBF.

Is the exposed thermal pad on the LTC2905CDDB#TRMPBF's DFN package electrically connected?

Yes, the exposed pad on the LTC2905CDDB#TRMPBF's 8-lead DFN package (Pin 9) is internally connected to GND and must be soldered to a PCB ground plane. This connection provides both thermal dissipation (reducing θJA to 76°C/W) and electrical noise immunity. Failure to solder the pad may result in elevated junction temperature, degraded long-term reliability, and increased susceptibility to supply noise - compromising the precision monitoring function of the LTC2905CDDB#TRMPBF.