Texas Instruments TPS3705-30DGN

Overview

TPS3705-30DGN from Texas Instruments is a precision processor supervisory IC with integrated watchdog timer, 3.0 V supply voltage monitoring (V_IT– = 2.63 V), 200 ms power-on reset delay, and power-fail comparator functionality. It operates over –40°C to 85°C in an 8-pin MSOP-PowerPAD package and is used for reliable system initialization and fault detection in microcontroller-based industrial control units.

For engineers reviewing the TPS3705-30DGN datasheet, TPS3705-30DGN pinout, TPS3705-30DGN application, or TPS3705-30DGN equivalent, key selection criteria include its fixed 200 ms reset timeout, low 50 µA supply current, active-low RESET output, PFI/PFO power-fail warning interface, and watchdog timeout of 1.6 s - all critical for fail-safe embedded power sequencing and brownout recovery.

Technical Context

The TPS3705-30DGN implements dual supervision: a precision bandgap-referenced V_DD monitor with 50 mV hysteresis and a separate PFI comparator with 10 mV hysteresis and 1.25 V threshold. Its internal oscillator drives a watchdog timer that requires periodic WDI transitions to prevent WDO assertion.

Reset assertion occurs when V_DD falls below 2.63 V or rises above it after power-up (with 200 ms delay), while PFO activates when PFI drops below 1.25 V - enabling independent monitoring of auxiliary rails like battery or backup supplies without external components.

Key Specifications

Pinout & Package

TPS3705-30DGN uses an 8-pin MSOP-PowerPAD package with exposed thermal pad (pin 5 connected to GND). The PowerPAD improves thermal performance and must be soldered to PCB ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar processor supervision applications.

Compared with TPS3705-30DGN, both alternatives offer lower supply current but omit the integrated watchdog timer and dedicated PFI/PFO power-fail interface - making them unsuitable for applications requiring concurrent main-rail supervision, auxiliary supply monitoring, and firmware hang recovery.

Availability

TPS3705-30DGN is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and portable medical device designs requiring stable component supply, long-term manufacturability, and guaranteed temperature-grade availability.

Supply support for TPS3705-30DGN 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 leader specializing in analog, embedded processing, and power management technologies with decades of experience in high-reliability supervisory circuits.

The TPS370x family was designed specifically for robust power sequencing and fault detection in DSP, MCU, and MPU-based systems - emphasizing precision thresholds, low power, and integrated watchdog functionality for mission-critical embedded applications.

FAQ

What is the exact reset threshold voltage for TPS3705-30DGN?

The TPS3705-30DGN has a nominal negative-going V_DD threshold voltage (V_IT–) of 2.63 V, with a tolerance of ±0.06 V over the full –40°C to 85°C operating range. This value is factory-trimmed and specified in Section 7.5 of the datasheet. The TPS3705-30DGN uses this threshold to assert RESET when V_DD drops below 2.63 V or during initial power-up until V_DD exceeds it with 200 ms delay.

Does TPS3705-30DGN require an external capacitor for reset timing?

No, the TPS3705-30DGN does not require an external capacitor for its 200 ms power-on reset delay. The timing is generated by an internal oscillator and counter, eliminating component count and layout variability. This fixed delay is guaranteed across temperature and supply voltage for the TPS3705-30DGN and is explicitly stated in the Features section of the datasheet.

How is the power-fail function implemented in TPS3705-30DGN?

The TPS3705-30DGN implements power-fail detection via the PFI (Power-Fail Input) pin, which compares an external voltage - typically derived from a resistor divider on a secondary supply - against an internal 1.25 V reference. When PFI falls below 1.25 V, the open-drain PFO output goes low. This allows the TPS3705-30DGN to independently monitor battery or backup rails without affecting the main V_DD supervision path.

Can the watchdog timer in TPS3705-30DGN be disabled?

Yes, the watchdog timer in the TPS3705-30DGN is disabled by leaving the WDI pin unconnected (floating). The datasheet states that "leaving WDI unconnected disables the watchdog." No pull-up or pull-down is required. When enabled, the watchdog requires periodic rising or falling edges on WDI to prevent WDO assertion; its timeout is 1.6 s typical, as confirmed in Section 7.8.

What is the maximum supply voltage rating for TPS3705-30DGN?

The absolute maximum supply voltage (V_DD) for the TPS3705-30DGN is 7 V, as specified in Section 7.1 (Absolute Maximum Ratings). However, for reliable continuous operation, the datasheet limits V_DD to 6 V maximum under Recommended Operating Conditions (Section 7.3), and warns that operation at 7 V should not exceed 1000 hours. The TPS3705-30DGN is designed for 2 V to 6 V operation.