Analog Devices Inc./Maxim Integrated DS1834AS/T&R

Overview

DS1834AS/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 DS1834AS/T&R datasheet, DS1834AS/T&R pinout, DS1834AS/T&R application, or DS1834AS/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 output drive capability (10 mA sink), and operation across -40°C to +85°C industrial temperature range.

Technical Context

The DS1834AS/T&R integrates two independent voltage monitors with 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, enabling seamless dual-supply operation.

Its pushbutton reset circuit includes internal debouncing and forces both RST outputs active for ~350 ms after PBRST release. The CMOS push-pull outputs maintain valid logic states down to 1.2 V supply and support direct interfacing with 5V/3.3V logic without external pull-ups-unlike the open-drain DS1834A variant requiring external resistors.

Key Specifications

Pinout & Package

DS1834AS/T&R is supplied in an 8-pin SOIC (150-mil) package with industry-standard footprint and thermal profile suitable for reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326US29D3+ and TPS3808G33DBVR, DS1834AS/T&R delivers unique dual-supply supervision with hardware-configurable tolerances and integrated pushbutton reset-enabling single-chip replacement of two discrete supervisors plus debounce circuitry in space-constrained industrial and automotive systems.

Availability

DS1834AS/T&R is available at Aetrix Electronics and suitable for industrial automation controllers, network infrastructure equipment, medical diagnostic devices, and automotive infotainment systems requiring stable component supply and long-term lifecycle support.

Supply support for DS1834AS/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 high-performance analog, mixed-signal, and power management ICs for precision sensing, power integrity, and robust system control.

The DS1834AS/T&R belongs to Maxim's EconoReset™ family-engineered specifically for cost-sensitive, space-constrained embedded systems needing reliable dual-voltage supervision without software intervention or external components.

FAQ

What is the function of the 5V TOL and 3.3V TOL pins on the DS1834AS/T&R?

The 5V TOL and 3.3V TOL pins on the DS1834AS/T&R configure the voltage detection 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 hardware-based configuration eliminates calibration firmware and external resistors, making DS1834AS/T&R ideal for fixed-function industrial controllers where design simplicity and reliability are critical.

Does the DS1834AS/T&R require external pull-up resistors on its reset outputs?

No, the DS1834AS/T&R does not require external pull-up resistors on its 5V RST or 3.3V RST outputs because it features CMOS push-pull drivers capable of sourcing and sinking current. Unlike the DS1834A variant-which uses open-drain NMOS outputs and mandates external pull-ups-the DS1834AS/T&R can directly drive standard microcontroller reset inputs with guaranteed 10 mA sink capability, simplifying schematic design and reducing component count in the final DS1834AS/T&R implementation.

How does the DS1834AS/T&R handle power supply sequencing during startup?

During power-up, the DS1834AS/T&R holds both 5V RST and 3.3V RST active for approximately 350 ms after the monitored supplies reach their selected tolerance windows. This ensures that downstream processors and peripherals have sufficient time to stabilize before release-preventing race conditions and undefined behavior. The DS1834AS/T&R achieves this using internal timing circuitry independent of external capacitors, delivering consistent reset timing across temperature and voltage variations in every DS1834AS/T&R unit.

Can the DS1834AS/T&R operate if only one supply (e.g., 3.3VIN) is present?

Yes, the DS1834AS/T&R can operate with only 3.3VIN present, as its internal circuitry functions down to 1.2 V on either supply input. When only 3.3VIN is active, the device monitors that rail exclusively and asserts 3.3V RST during faults; 5V RST remains inactive (high) since no 5VIN is detected. This behavior allows flexible deployment in partial-power systems and supports graceful degradation modes-ensuring DS1834AS/T&R remains functional and predictable even under asymmetric supply conditions.

What is the minimum pulse width of the pushbutton reset signal required to trigger the DS1834AS/T&R?

The DS1834AS/T&R requires the PBRST pin to be held low for a minimum of 2 ms to register a valid pushbutton reset event. Once detected, the internal debouncer ensures noise immunity against contact bounce, and both reset outputs remain active for approximately 350 ms after PBRST returns high. This timing is guaranteed across the full -40°C to +85°C operating range and is implemented entirely in hardware-making DS1834AS/T&R suitable for rugged environments where mechanical switch reliability is critical.