Texas Instruments TPS3705-50DGNR

Overview

TPS3705-50DGNR from Texas Instruments is a precision 5-V supply voltage supervisor IC with integrated watchdog timer, power-fail comparator, and 200-ms fixed reset delay. It monitors V_DD at 4.55 V (V_IT–), asserts active-low RESET on undervoltage or manual reset, and provides WDO/WDI watchdog signaling. Used in microcontroller-based industrial control systems requiring reliable power sequencing and fault recovery.

For engineers reviewing the TPS3705-50DGNR datasheet, TPS3705-50DGNR pinout, TPS3705-50DGNR application, or TPS3705-50DGNR equivalent, key selection criteria include its 4.55-V threshold accuracy, 1.6-s watchdog timeout, 50 µA max supply current, MSOP-PowerPAD™ 8-pin package, and compatibility with MSP430 and other low-power embedded processors.

Technical Context

The TPS3705-50DGNR implements dual supervision: a precision bandgap-referenced comparator for V_DD monitoring (4.55 V ±2.5%) and a separate PFI/PFO comparator for secondary rail or battery voltage detection. Its internal oscillator drives a 1.6-s watchdog timeout, retriggerable via WDI edge transitions.

Reset assertion occurs when V_DD drops below 4.55 V (with 70-mV hysteresis) or MR is pulled low; RESET remains active for 200 ms after V_DD exceeds threshold. No external capacitor is required for reset timing, and all functions operate over –40°C to 85°C.

Key Specifications

Pinout & Package

TPS3705-50DGNR uses an 8-pin MSOP-PowerPAD™ package (3.00 mm × 3.00 mm), thermally enhanced with exposed die pad for improved power dissipation (R_θJB = 45.1°C/W).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with TPS3705-50DGNR, TPS3808G50DBVR offers lower quiescent current but omits watchdog and power-fail features, while MAX6326–50DUR-T reduces size and cost at the expense of functional integration-making TPS3705-50DGNR optimal for systems needing combined reset, watchdog, and auxiliary voltage monitoring in one IC.

Availability

TPS3705-50DGNR is available at Aetrix Electronics and suitable for industrial automation, automotive body electronics, and portable medical instrumentation requiring stable component supply and long-term manufacturability.

Supply support for TPS3705-50DGNR 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

Texas Instruments is a global semiconductor company delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The TPS370x family was designed specifically for robust power-supply supervision in microprocessor and DSP systems, integrating reset generation, watchdog timing, and auxiliary voltage monitoring in single-chip solutions.

FAQ

What is the exact reset threshold voltage for TPS3705-50DGNR?

The TPS3705-50DGNR has a guaranteed negative-going input threshold voltage (V_IT–) of 4.45 V minimum, 4.55 V typical, and 4.65 V maximum at –40°C to 85°C. This 5-V nominal threshold is factory-trimmed and referenced to an internal 1.25-V bandgap, ensuring stable performance across temperature and supply variations. The 70-mV hysteresis prevents oscillation during slow voltage transitions.

Does TPS3705-50DGNR require an external capacitor for reset timing?

No, TPS3705-50DGNR does not require an external capacitor for its 200-ms power-on reset delay. The timing is generated internally using a precision oscillator and RC network, eliminating component count, board space, and tolerance-related drift. This fixed delay is specified from the moment V_DD exceeds 1.1 V until RESET deassertion, and applies across the full operating temperature range.

How is the watchdog function enabled or disabled on TPS3705-50DGNR?

The watchdog function on TPS3705-50DGNR is enabled by connecting a valid clock or toggle signal to the WDI pin; leaving WDI unconnected disables the watchdog. To maintain normal operation, the WDI input must receive a rising or falling edge at least once every 1.6 s (typical timeout). If no transition occurs, WDO asserts low. The watchdog operates independently of V_DD supervision and remains functional as long as V_DD is ≥2 V.

Can TPS3705-50DGNR monitor a 12-V supply rail?

Yes, TPS3705-50DGNR can monitor a 12-V rail using its PFI input with an external resistor divider. The internal 1.25-V reference sets the trip point: for example, a 910-kΩ/120-kΩ divider yields ~1.25 V at PFI when the 12-V rail drops to ~10.73 V. PFI accepts voltages from 0 to V_DD, and the resulting PFO output signals low when the divided voltage falls below 1.25 V, enabling precise high-voltage rail supervision.

What package type and thermal performance does TPS3705-50DGNR offer?

TPS3705-50DGNR is supplied in an 8-pin MSOP-PowerPAD™ (DGN) package measuring 3.00 mm × 3.00 mm with an exposed thermal pad. Its junction-to-board thermal resistance (R_θJB) is 45.1°C/W, supporting up to 2.14 W power dissipation at 25°C ambient. This thermal design enables reliable operation in compact, high-density layouts without additional heatsinking, especially important in industrial and automotive applications with limited airflow.