Analog Devices Inc./Maxim Integrated DS1834S/T&R

Overview

DS1834S/T&R from Maxim Integrated (now Analog Devices) is a dual-voltage power-on reset supervisor IC monitoring both 5V and 3.3V supplies with independent tolerance selection, pushbutton reset input, and CMOS push-pull outputs. It asserts active-low reset signals for each rail during out-of-tolerance conditions or manual override, with guaranteed 350 ms reset pulse width after recovery. Used in embedded systems with dual-supply microcontrollers requiring reliable power sequencing and brownout protection.

For engineers reviewing the DS1834S/T&R datasheet, DS1834S/T&R pinout, DS1834S/T&R application, or DS1834S/T&R equivalent, key selection criteria include dual-rail trip point configurability (5% or 10% for 5V; 10% or 20% for 3.3V), internal 40 kΩ pull-up on PBRST, push-pull RST output structure enabling valid logic down to 0 V, and operation across –40°C to +85°C.

Technical Context

The DS1834S/T&R integrates two independent voltage monitors with user-selectable trip thresholds via dedicated TOL pins-5V TOL tied to GND sets 5% tolerance (4.50–4.75 V), while tied to 5VIN sets 10% (4.25–4.49 V); similarly, 3.3V TOL selects 10% (2.80–2.97 V) or 20% (2.47–2.64 V). Internal power routing draws current from the higher of 5VIN or 3.3VIN, ensuring stable operation during asymmetric supply ramp-up.

Its push-pull RST outputs eliminate external pull-ups required by open-drain variants (e.g., DS1834A), support direct interfacing to CMOS inputs, and maintain valid logic states even when both supplies drop below 1.2 V-enabled by optional external 100 kΩ pull-down resistors to GND. The internally debounced PBRST input requires only ≥2 ms low assertion to trigger synchronized 350 ms reset pulses on both outputs.

Key Specifications

Pinout & Package

DS1834S/T&R is supplied in an 8-pin SOIC (150-mil) package, pin-compatible with industry-standard 8-pin SOIC footprints. The device uses a standard SOIC-8 outline with 1.27 mm pitch and gull-wing leads.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326UT46D3+ and TPS3808G33DBVR, the DS1834S/T&R uniquely delivers simultaneous 5V/3.3V monitoring with independent tolerance configuration, integrated pushbutton interface, and push-pull outputs-making it the only option among the three capable of coordinating reset timing across two voltage domains without external components.

Availability

DS1834S/T&R is available at Aetrix Electronics and suitable for industrial automation controllers, medical diagnostic instruments, telecom baseband processors, and automotive infotainment head units requiring stable component supply and long-term lifecycle assurance.

Supply support for DS1834S/T&R 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 (via acquisition of Maxim Integrated) designs precision analog, mixed-signal, and power management ICs for high-reliability industrial, automotive, and communications systems.

The DS1834S/T&R belongs to Maxim's EconoReset™ family-engineered specifically for cost-sensitive, dual-rail embedded systems needing robust power monitoring without sacrificing configurability or integration.

FAQ

What is the function of the 5V TOL and 3.3V TOL pins on the DS1834S/T&R?

The 5V TOL and 3.3V TOL pins configure the voltage monitor trip thresholds: tying 5V TOL to GND selects a 5% tolerance (4.50–4.75 V), while tying it to 5VIN selects 10% (4.25–4.49 V); similarly, 3.3V TOL selects 10% or 20% for the 3.3V rail. This allows the DS1834S/T&R to adapt to varying supply regulation quality without redesigning the PCB. Each setting is independently selectable, enabling asymmetric tolerance tuning per rail.

Does the DS1834S/T&R require external pull-up resistors on its RST outputs?

No, the DS1834S/T&R features CMOS push-pull RST outputs that actively drive both high and low states, eliminating the need for external pull-up resistors. This distinguishes it from the DS1834A variant, which uses open-drain NMOS outputs and requires external pull-ups. The DS1834S/T&R's push-pull architecture simplifies design, reduces component count, and ensures fast, rail-to-rail logic transitions directly compatible with standard CMOS inputs.

How does the DS1834S/T&R handle power sequencing when both 5VIN and 3.3VIN are present?

The DS1834S/T&R automatically draws internal operating current from the higher of the two supply inputs (5VIN or 3.3VIN), ensuring stable biasing regardless of ramp order. Its dual independent monitors operate concurrently-so if 5VIN rises first and falls out of tolerance while 3.3VIN remains valid, only 5V RST asserts. This behavior makes the DS1834S/T&R ideal for systems where supply sequencing is uncontrolled or asymmetric, such as those using discrete regulators or aging power modules.

What is the minimum pulse width required on PBRST to trigger a reset on the DS1834S/T&R?

The DS1834S/T&R requires the PBRST pin to be held low for a minimum of 2 ms to register a valid pushbutton event. Once detected, the internal debounce circuit locks the condition and asserts both 5V RST and 3.3V RST for 200–500 ms after PBRST returns high. This 2 ms threshold rejects mechanical switch bounce and EMI-induced glitches, ensuring that the DS1834S/T&R generates only intentional, clean reset pulses without firmware intervention.

Can the DS1834S/T&R maintain valid RST output states when both 5VIN and 3.3VIN drop to 0 V?

Yes-the DS1834S/T&R can sustain valid RST logic states down to 0 V when external 100 kΩ pull-down resistors are connected from each RST pin to GND. This configuration allows the outputs to remain low (active) even after full supply collapse, supporting fail-safe shutdown protocols. Without these resistors, valid output operation ceases below ~1.2 V; with them, the DS1834S/T&R continues asserting reset during complete power loss, a critical capability for safety-critical systems.