Analog Devices Inc. LTC2905IDDB#TRMPBF

Overview

LTC2905IDDB#TRMPBF from Analog Devices (formerly Linear Technology) is a precision dual supply voltage monitor IC with adjustable reset timeout, open-drain RST output, ±1.5% threshold accuracy over –40°C to +85°C, and pin-selectable thresholds for V1 (5V/3.3V/2.5V) and V2 (3.3V/2.5V/1.8V/1.5V/1.2V/1.0V). It serves as a system-level power-good supervisor in embedded computing and industrial control applications requiring reliable brownout detection.

For engineers reviewing the LTC2905IDDB#TRMPBF datasheet, LTC2905IDDB#TRMPBF pinout, LTC2905IDDB#TRMPBF application, or LTC2905IDDB#TRMPBF equivalent, key selection criteria include its DFN-8 (3mm × 2mm) package, TMR pin-based reset delay programming (e.g., 200ms with 22nF), guaranteed RST operation down to V1 ≥ 1V or V2 ≥ 1V, and three-state input programming for nine voltage combinations and three tolerance levels (5%/7.5%/10%).

Technical Context

The LTC2905IDDB#TRMPBF integrates two independent high-accuracy comparators with a shared bandgap reference and programmable resistor network. Its internal VCC is auto-selected as the greater of V1 or V2, enabling operation from 1V inputs while powering both monitoring circuitry and the open-drain RST output driver.

Reset assertion is triggered when either monitored supply falls below its programmed threshold; recovery requires both supplies to remain above threshold for the full TMR-programmed delay. Glitch immunity is achieved via comparator output integration and the external timing capacitor, eliminating need for hysteresis without sacrificing threshold accuracy.

Key Specifications

Pinout & Package

Package: 8-lead (3mm × 2mm) plastic DFN with exposed thermal pad (Pin 9 = GND, must be soldered to PCB).

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 LTC2905IDDB#TRMPBF uniquely integrates dual-rail monitoring, pin-selectable thresholds, and ±1.5% accuracy in a single DFN-8 package-reducing component count, layout complexity, and calibration overhead in space-constrained designs.

Availability

LTC2905IDDB#TRMPBF is available at Aetrix Electronics and suitable for desktop computers, network servers, handheld devices, and industrial embedded controllers requiring stable component supply across extended temperature ranges.

Supply support for LTC2905IDDB#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 acquired Linear Technology in 2017 and maintains its precision analog and power management product lines with full technical support and long-term manufacturing commitment.

The LTC2905IDDB#TRMPBF belongs to Linear's LTC290x family of precision voltage supervisors, designed specifically for high-reliability embedded systems where deterministic power sequencing and brownout protection are critical.

FAQ

What is the operating temperature range for the LTC2905IDDB#TRMPBF?

The LTC2905IDDB#TRMPBF is rated for –40°C to +85°C (Industrial grade). This is confirmed by the "I" suffix in the part number and explicitly listed in the Order Information table under Temperature Range. The device maintains ±1.5% threshold accuracy across this full range, making it suitable for automotive cabin, industrial control, and outdoor communications equipment.

How do I configure the LTC2905IDDB#TRMPBF to monitor 3.3V and 1.2V supplies with 5% tolerance?

To configure the LTC2905IDDB#TRMPBF for 3.3V and 1.2V with 5% tolerance, set S1 = Open, S2 = Open (per Table 1), and TOL = V1 (per Table 2). This selects V1=3.3V, V2=1.2V, and 5% tolerance, resulting in trip thresholds of 3.135V and 1.14V respectively. Ensure V1 is connected to the 3.3V rail to power the TOL pin correctly.

Can the LTC2905IDDB#TRMPBF operate if only one supply is present?

Yes - the LTC2905IDDB#TRMPBF can operate with only V1 or only V2 present, provided that supply is ≥1V. Its internal VCC is derived from the greater of V1 or V2, so a single 3.3V rail powers all circuitry. However, the unconnected input (e.g., V2 if unused) must be tied to GND or a valid voltage to avoid floating node issues; leaving it open is not recommended.

What is the minimum and maximum reset timeout achievable with the TMR pin on the LTC2905IDDB#TRMPBF?

The TMR pin on the LTC2905IDDB#TRMPBF supports a reset timeout range from approximately 200μs (TMR pin left open) up to several seconds. With CTMR = 22nF, tRST ≈ 200ms. Using the formula CTMR = tRST × 110 nF/s, a 1μF capacitor yields ~9.1s. Practical upper limit is constrained by capacitor leakage; TMR charging current is ≥2.1μA, so CTMR must have leakage <2.1μA at rated voltage.

Does the LTC2905IDDB#TRMPBF require external pull-up resistors on the RST pin?

The LTC2905IDDB#TRMPBF includes a weak internal pull-up to VCC on the RST pin, sufficient for non-critical rise-time applications. However, an external pull-up (e.g., 10kΩ) is recommended when fast rise time (<1μs) or VOH > VCC is required. Note that adding external pull-up increases total pull-up strength, which must be overcome by any wired-OR device sharing the RST line.