Analog Devices Inc. LTC2905CTS8#TRPBF

Overview

LTC2905CTS8#TRPBF from Analog Devices (formerly Linear Technology) is a precision dual supply monitor IC with pin-selectable thresholds and adjustable reset timeout, designed for systems requiring simultaneous monitoring of two independent voltage rails. It delivers ±1.5% threshold accuracy over temperature, open-drain RST output guaranteed functional down to 1V input, and supports nine V1/V2 combinations (e.g., 5V/3.3V, 3.3V/1.2V) with 5%/7.5%/10% tolerance selection - used in desktop computers, network servers, and embedded logic power sequencing.

For engineers reviewing the LTC2905CTS8#TRPBF datasheet, LTC2905CTS8#TRPBF pinout, LTC2905CTS8#TRPBF application, or LTC2905CTS8#TRPBF equivalent, key selection criteria include its TSOT-23-8 package, adjustable 200μs–295ms reset delay via external capacitor on TMR pin, guaranteed RST operation at V1 ≥ 1V or V2 ≥ 1V, and three-state programming pins (S1/S2/TOL) enabling 27 voltage/tolerance configurations without external resistors.

Technical Context

The LTC2905CTS8#TRPBF implements two independent comparators referenced to a bandgap-based precision voltage reference, with threshold selection decoded from three 3-state inputs (S1, S2, TOL). Its internal power detect circuit uses the higher of V1 or V2 as VCC, enabling operation during brownout when either rail remains ≥1V.

Reset assertion is glitch-immune due to integrated low-pass filtering at comparator outputs and a programmable timeout timer triggered only after sustained undervoltage. The TMR pin accepts an external capacitor (CTMR) to set tRST = 9 ms/nF, with 22nF yielding 200ms - unlike the fixed 200ms delay in LTC2904 variants.

Key Specifications

Pinout & Package

Package: 8-lead Plastic TSOT-23 (3.0mm × 1.75mm × 0.9mm height), RoHS-compliant, lead-free finish. Exposed pad not present; pin 1 marked by beveled corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6816ETA+ and TPS3808G18DBVR, the LTC2905CTS8#TRPBF uniquely supports 9 dual-voltage combinations with ±1.5% accuracy and field-adjustable reset timing - reducing BOM count, improving design margin, and eliminating external timing components in space-constrained systems.

Availability

LTC2905CTS8#TRPBF is available at Aetrix Electronics and suitable for desktop computers, network servers, handheld devices, and industrial embedded controllers requiring stable component supply across commercial temperature range (0°C to 70°C).

Supply support for LTC2905CTS8#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 acquired Linear Technology in 2017 and maintains its high-precision analog IC portfolio, emphasizing reliability, accuracy, and low-power operation for mission-critical systems.

The LTC2905CTS8#TRPBF belongs to Linear's supervisor IC product line, engineered specifically for robust power-rail monitoring in computing, communications, and industrial equipment where deterministic reset behavior under voltage fault conditions is essential.

FAQ

What is the function of the TMR pin on the LTC2905CTS8#TRPBF?

The TMR pin on the LTC2905CTS8#TRPBF is the reset timeout programming terminal. Connecting an external capacitor (CTMR) between TMR and GND sets the reset delay period tRST = 9 ms/nF; a 22nF capacitor yields 200ms. Leaving TMR open results in ~200μs minimum delay. This pin distinguishes LTC2905CTS8#TRPBF from the fixed-delay LTC2904 series and enables precise timing alignment with microprocessor power-up requirements.

Can the LTC2905CTS8#TRPBF monitor a 5V and a 1.2V supply simultaneously?

Yes, the LTC2905CTS8#TRPBF can monitor 5V and 1.2V supplies simultaneously. Configure S1=V1, S2=Open, and TOL=GND per Table 1 and Table 2 to select V1=5V and V2=1.2V with 10% tolerance. The resulting thresholds are VRT50=4.500V (min) and VRT12=1.080V (min), both guaranteed accurate to ±1.5% over temperature. This configuration is explicitly supported in the LTC2904/LTC2905 datasheet.

What is the minimum supply voltage required for the LTC2905CTS8#TRPBF to assert a valid RST signal?

The LTC2905CTS8#TRPBF guarantees correct RST logic state when either V1 ≥ 1V or V2 ≥ 1V. At this level, the internal circuitry powered by the higher of V1/V2 (VCC) ensures VOL ≤ 0.4V on the RST pin under 2.5mA load. This brownout resilience allows the LTC2905CTS8#TRPBF to maintain deterministic reset behavior even when one rail collapses while the other remains marginally active.

How does the LTC2905CTS8#TRPBF achieve ±1.5% threshold accuracy without external components?

The LTC2905CTS8#TRPBF achieves ±1.5% threshold accuracy using a trimmed bandgap reference and laser-trimmed resistor network internal to the die. Threshold voltages are derived from ratios of this precision reference, eliminating dependence on external resistor tolerances. The datasheet confirms this accuracy is maintained over –40°C to 125°C for H-grade parts and 0°C to 70°C for the C-grade LTC2905CTS8#TRPBF, with no calibration or external parts required.

Is the LTC2905CTS8#TRPBF pin-compatible with the LTC2904CTS8#TRPBF?

No, the LTC2905CTS8#TRPBF is not pin-compatible with the LTC2904CTS8#TRPBF. While both use TSOT-23-8 packages, Pin 2 is TMR (capacitor input) on LTC2905CTS8#TRPBF but RST (reset output) on LTC2904CTS8#TRPBF, and Pin 3 is RST (inverted output) on LTC2905CTS8#TRPBF but RST (non-inverted output) on LTC2904CTS8#TRPBF. PCB layout must be redesigned to accommodate these functional pin swaps.