Analog Devices Inc. LTC1728ES5-3.3#TRMPBF

Overview

LTC1728ES5-3.3#TRMPBF from Analog Devices is a micropower precision triple supply monitor in 5-lead SOT-23 package, monitoring 3.3V, 1.8V, and adjustable (1.0V) supply rails with ±1.5% threshold accuracy over temperature, 10µA typical supply current, and 200ms reset delay. It delivers active-low open-drain RST output for microprocessor reset in portable battery-powered equipment and intelligent instruments.

For engineers reviewing the LTC1728ES5-3.3#TRMPBF datasheet, LTC1728ES5-3.3#TRMPBF pinout, LTC1728ES5-3.3#TRMPBF application, or LTC1728ES5-3.3#TRMPBF equivalent, key selection criteria include guaranteed RST assertion down to VCC3 ≥ 1V or VCC18 ≥ 1V, glitch-immune undervoltage detection, and compatibility with 3.3V/1.8V dual-rail systems requiring stable power-on reset sequencing.

Technical Context

The LTC1728ES5-3.3#TRMPBF implements three independent voltage comparators feeding a 200ms monostable pulse generator that drives the open-drain RST output. Its internal bandgap reference enables accurate threshold detection across –40°C to 85°C, with power detect logic selecting VCC3 or VCC18 as the operating supply based on highest potential.

Reset assertion occurs when any monitored rail falls below its specified threshold (VRT3 = 3.086V, VRT18 = 1.683V, VRTA = 1.000V), and release requires all rails to remain above thresholds for 200ms. The device guarantees correct RST state down to 1V on either VCC3 or VCC18, ensuring reliable operation during brownout conditions.

Key Specifications

Pinout & Package

Package: 5-Lead Plastic TSOT-23 (S5), 1.90mm × 1.50mm footprint, 0.95mm height, JEDEC MO-193 compliant, lead-free finish.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1985-1.8 and LTC1326-2.5, the LTC1728ES5-3.3#TRMPBF offers optimal trade-off between ultra-low 10µA quiescent current, guaranteed 1V operation, and compact 5-lead SOT-23 footprint - making it preferred for battery-critical portable designs where open-drain flexibility and brownout resilience are prioritized over push-pull convenience or sub-1% accuracy.

Availability

LTC1728ES5-3.3#TRMPBF is available at Aetrix Electronics and suitable for desktop computers, notebook computers, and portable battery-powered equipment requiring stable component supply with guaranteed long-term availability.

Supply support for LTC1728ES5-3.3#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.

The LTC1728 belongs to Analog Devices' precision power monitoring product line, designed specifically for reliable reset generation in multi-rail embedded systems where accuracy, low power, and small footprint are critical.

FAQ

What is the exact reset threshold voltage for the 3.3V input on the LTC1728ES5-3.3#TRMPBF?

The LTC1728ES5-3.3#TRMPBF has a guaranteed VRT3 reset threshold of 3.086V ±1.5% over temperature (–40°C to 85°C). This value is measured at the VCC3 pin and defines the precise voltage below which the RST output is asserted. The specification ensures deterministic behavior across full industrial temperature range without calibration.

Can the LTC1728ES5-3.3#TRMPBF operate when only the 1.8V rail is present and the 3.3V rail is absent?

Yes, the LTC1728ES5-3.3#TRMPBF can operate from the VCC18 pin alone when VCC18 ≥ 1V, even if VCC3 is unpowered. Its power-detect logic automatically selects VCC18 as the supply source, and RST remains valid. However, the 3.3V rail monitoring function remains active and will assert reset if VCC3 falls below 3.086V once applied.

What is the minimum supply voltage required to guarantee correct RST logic state on the LTC1728ES5-3.3#TRMPBF?

The LTC1728ES5-3.3#TRMPBF guarantees correct RST logic state when either VCC3 ≥ 1V or VCC18 ≥ 1V. This 1V minimum ensures fail-safe reset assertion during deep brownout conditions, a key reliability feature distinguishing it from standard supervisors requiring ≥2V operation.

Does the LTC1728ES5-3.3#TRMPBF support manual reset functionality?

No, the LTC1728ES5-3.3#TRMPBF does not include a dedicated manual reset input. It provides only automatic reset based on monitored supply voltages. For manual reset capability, consider the LTC1727 series (e.g., LTC1727ES8-3.3#PBF) or alternative parts like LTC1232 that integrate push-button reset inputs.

How does the LTC1728ES5-3.3#TRMPBF handle noise on the VCCA adjustable input?

The LTC1728ES5-3.3#TRMPBF's VCCA comparator has no built-in hysteresis, so slow-moving or ripple-contaminated signals near the 1.000V threshold may cause output toggling. To prevent this, use a low-pass RC filter (e.g., 10kΩ + 100nF) on VCCA or ensure the monitored rail has sufficient inherent stability - design practice confirmed in Analog Devices' Application Note AN70.