Analog Devices Inc./Maxim Integrated DS1834U/T&R

Overview

DS1834U/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 override, and CMOS push-pull reset outputs. It asserts active-low resets for 350 ms after supply recovery and draws internal current from the higher of the two input rails. Used in embedded systems requiring reliable dual-rail power sequencing and manual reset capability.

For engineers reviewing the DS1834U/T&R datasheet, DS1834U/T&R pinout, DS1834U/T&R application, or DS1834U/T&R equivalent, key selection criteria include dual-supply trip point configurability (5%–10% for 5V, 10%–20% for 3.3V), 350 ms reset timeout, push-pull output drive, -40°C to +85°C operation, and compatibility with SOIC-8 packaging.

Technical Context

The DS1834U/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), tied to 5VIN sets 10% (4.25–4.49 V); 3.3V TOL tied to GND sets 10% (2.80–2.97 V), tied to 3.3VIN sets 20% (2.47–2.64 V). Internal precision temperature-compensated reference ensures stable threshold tracking across temperature.

It features an internally debounced PBRST input with 40 kΩ pull-up to VIN(MAX), triggering simultaneous 350 ms reset assertion on both RST outputs when pulled low ≥2 ms. Power-fail detection occurs as either supply drops below its configured threshold, and reset remains asserted for 350 ms after return to tolerance.

Key Specifications

Pinout & Package

DS1834U/T&R is supplied in 8-pin SOIC (150-mil) package. Pin functions are electrically identical across DS1834 variants and validated per Maxim Integrated datasheet revision 071700.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6326US29D3+ and TPS3808G33DBVR, DS1834U/T&R uniquely provides integrated dual-rail monitoring with hardware-selectable thresholds and pushbutton override in a single SOIC-8 package - eliminating design complexity and component count for systems requiring coordinated 3.3V/5V reset behavior.

Availability

DS1834U/T&R is available at Aetrix Electronics and suitable for industrial PLC controllers, medical diagnostic devices, telecom line cards, and automotive infotainment head units requiring stable component supply and long-term lifecycle support.

Supply support for DS1834U/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 industrial, automotive, and communications applications.

The DS1834U/T&R belongs to Maxim's EconoReset family - engineered specifically for cost-sensitive, space-constrained embedded systems needing robust dual-voltage power supervision without external components.

FAQ

What is the function of the 5V TOL and 3.3V TOL pins on the DS1834U/T&R?

The 5V TOL and 3.3V TOL pins on the DS1834U/T&R configure the voltage trip thresholds for their respective supplies. 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 to GND sets 10% (2.80–2.97 V), and to 3.3VIN sets 20% (2.47–2.64 V). This hardware-based configuration eliminates software calibration and ensures deterministic reset behavior in the DS1834U/T&R.

Does the DS1834U/T&R require external pull-up resistors on its RST outputs?

No, the DS1834U/T&R does not require external pull-up resistors on its RST outputs. It uses CMOS push-pull drivers capable of actively driving both high and low states. This design reduces BOM count and improves noise immunity compared to open-drain alternatives. The DS1834U/T&R datasheet confirms this architecture applies to the DS1834 and DS1834D variants, which include the DS1834U/T&R part number.

How long does the DS1834U/T&R hold reset after a power supply returns to tolerance?

The DS1834U/T&R holds reset for 200–500 ms after a monitored supply returns to its configured tolerance window, with a typical duration of 350 ms. This timing is guaranteed across -40°C to +85°C and applies to both 5V RST and 3.3V RST outputs. The same 350 ms timeout also governs pushbutton-initiated reset assertion, ensuring consistent system initialization timing in the DS1834U/T&R.

Can the DS1834U/T&R operate if only one supply rail is present?

Yes, the DS1834U/T&R can operate with only one supply rail active - either 5VIN or 3.3VIN - as long as that rail is ≥1.2 V. Internal current is drawn from the higher of the two inputs, but functionality remains intact with just one rail. The DS1834U/T&R will monitor the active rail and assert its corresponding RST output if that rail falls out of tolerance, while the unused rail's RST remains inactive.

What is the purpose of the PBRST pin on the DS1834U/T&R?

The PBRST pin on the DS1834U/T&R provides a debounced, internally pulled-up (40 kΩ to VIN(MAX)) interface for manual system reset. Pulling PBRST low for ≥2 ms triggers simultaneous assertion of both 5V RST and 3.3V RST for ~350 ms after release. This eliminates external debounce circuitry and firmware handling, enabling reliable hardware-initiated reboot - a critical feature for field-serviceable equipment using the DS1834U/T&R.