Analog Devices Inc. LTC1726EMS8-2.5#PBF

Overview

LTC1726EMS8-2.5#PBF from Analog Devices (formerly Linear Technology) is a micropower triple supply monitor and microprocessor supervisory IC designed for systems requiring simultaneous monitoring of 2.5V, 3.3V, and an adjustable voltage rail. It features ±1.5% threshold accuracy over temperature, adjustable reset timeout (via RT pin capacitor), adjustable watchdog timeout (via WT pin capacitor), and guaranteed RST assertion down to VCC3 ≥ 1V or VCC25 ≥ 1V. It is used in notebook computers and portable battery-powered equipment where reliable power-up sequencing and brownout protection are critical.

For engineers reviewing the LTC1726EMS8-2.5#PBF datasheet, LTC1726EMS8-2.5#PBF pinout, LTC1726EMS8-2.5#PBF application, or LTC1726EMS8-2.5#PBF equivalent, key selection considerations include its 2.5V/3.3V/ADJ triple-monitor configuration, MS8 package footprint, 16µA typical supply current, open-drain active-low RST output with weak internal pull-up to VCC3, and compatibility with ceramic timing capacitors for reset and watchdog periods.

Technical Context

The LTC1726EMS8-2.5#PBF implements three independent voltage comparators with precision bandgap references to monitor VCC25 (2.5V nominal), VCC3 (3.3V nominal), and VCCA (adjustable, 1V nominal). Its reset logic asserts RST low when any monitored supply falls below its trip threshold - VRT25 = 2.337V (typ), VRT3 = 3.085V (typ), VRTA = 1.000V (typ) - and holds RST asserted for a user-defined delay set by CRT on the RT pin.

Watchdog functionality is implemented via a charge/discharge timer on the WT pin, cleared by edges on WDI; timeout occurs if no edge is detected within tWT = 21.8 × CWT (µs, CWT in pF). The device derives operating power from the highest potential among VCC25 and VCC3, ensuring RST remains valid during partial power-up, and guarantees correct RST state even as VCC25 or VCC3 drops to 1V.

Key Specifications

Pinout & Package

Package: 8-lead plastic MSOP (MS8), 3.0mm × 3.0mm × 0.86mm body, 0.65mm pitch, exposed pad not electrically connected. RoHS-compliant lead-free finish (PBF).

Key Features

Applications

Equivalent & Alternatives

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

Compared with LTC1326-2.5 and LTC1727-2.5, the LTC1726EMS8-2.5#PBF offers the optimal balance of accuracy (±1.5%), integrated watchdog, compact MSOP-8 footprint, and common open-drain RST - making it ideal for space-constrained, cost-sensitive designs requiring both supervision and fail-safe recovery.

Availability

LTC1726EMS8-2.5#PBF is available at Aetrix Electronics and suitable for notebook computers, intelligent instruments, and portable battery-powered equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for LTC1726EMS8-2.5#PBF 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 LTC1726 product line was developed specifically for high-reliability power supervision in computing and portable electronics, emphasizing low quiescent current, tight threshold tolerance, and flexible multi-rail monitoring architecture.

FAQ

What is the function of the VCCA pin on the LTC1726EMS8-2.5#PBF?

The VCCA pin on the LTC1726EMS8-2.5#PBF is a high-impedance input for monitoring an adjustable voltage rail, with a nominal threshold of 1.000V (±1.5%). When unused, it may be tied to VCC3 or VCC25. It cannot serve as a power source, and its trip point is fixed - unlike VCC25 and VCC3, which have factory-trimmed thresholds for 2.5V and 3.3V rails respectively. The LTC1726EMS8-2.5#PBF uses this pin to enable triple-supply monitoring without external resistor dividers.

How do I calculate the reset timeout period for the LTC1726EMS8-2.5#PBF?

The reset timeout period tRT for the LTC1726EMS8-2.5#PBF is calculated as tRT = 3.30 × CRT, where tRT is in microseconds and CRT is the capacitance (in picofarads) connected between the RT pin (Pin 8) and ground. For example, a 47nF (47,000pF) capacitor yields tRT ≈ 155ms. Ceramic capacitors are recommended due to low leakage. The LTC1726EMS8-2.5#PBF guarantees correct RST behavior throughout this delay, even if VCC25 or VCC3 drops to 1V.

Can the watchdog timer on the LTC1726EMS8-2.5#PBF be disabled?

Yes, the watchdog timer on the LTC1726EMS8-2.5#PBF can be disabled by connecting both the WDI (Pin 5) and WT (Pin 7) pins to ground. When disabled, the LTC1726EMS8-2.5#PBF operates strictly as a triple-supply monitor with adjustable reset timeout. This configuration preserves all voltage monitoring functionality while eliminating watchdog-related timing constraints - useful in systems where firmware cannot guarantee periodic WDI toggling.

What is the supply current specification for the LTC1726EMS8-2.5#PBF?

The LTC1726EMS8-2.5#PBF has a typical supply current of 16µA when VCC25 = 2.5V and VCC3 = 3.3V, with a maximum of 30µA over temperature. This ultra-low quiescent current is achieved through optimized comparator design and low-leakage internal references. The LTC1726EMS8-2.5#PBF draws power from whichever of VCC25 or VCC3 is at higher potential, enabling operation even during asymmetric power-up sequences.

Does the LTC1726EMS8-2.5#PBF support operation with only two supply rails?

Yes, the LTC1726EMS8-2.5#PBF can be configured to monitor only two supply rails. For example, VCCA may be tied to VCC3 or VCC25 (as permitted by datasheet guidance), effectively disabling that input. The device will then supervise only VCC25 and VCC3 - retaining full reset and watchdog functionality. This flexibility allows the LTC1726EMS8-2.5#PBF to adapt to system-level changes without requiring a different part number or redesign.