Texas Instruments TPS3705-50DR

Overview

TPS3705-50DR 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 (2–6 V), asserts active-low RESET during undervoltage or power fail, and provides WDI/WDO for system-level fault recovery in microprocessor-based systems.

For engineers reviewing the TPS3705-50DR datasheet, TPS3705-50DR pinout, TPS3705-50DR application, or TPS3705-50DR equivalent, key selection criteria include its 4.55-V V_IT– threshold, 1.6-s watchdog timeout, 50-µA max supply current, –40°C to 85°C operation, and compatibility with MSP430 and other low-power MCUs requiring robust power sequencing and fail-safe restart capability.

Technical Context

The TPS3705-50DR implements dual supervision: a precision bandgap-referenced V_DD monitor with 70-mV hysteresis and a separate PFI/PFO comparator for auxiliary rail monitoring (e.g., 12 V via resistor divider). Its internal oscillator drives a watchdog timer that times out after 1.6 s if WDI transitions cease - triggering WDO low and resetting the timer.

RESET assertion occurs when V_DD drops below 4.55 V (V_IT–) or rises from <1.1 V, with a guaranteed 200-ms delay before deassertion. MR input enables manual reset with 50-ns propagation delay, while all outputs are CMOS-compatible with rail-to-rail swing and 2.5-mA sink capability on RESET.

Key Specifications

Pinout & Package

TPS3705-50DR is available in 8-pin SOIC (D) package (3.90 mm × 4.90 mm) and 8-pin MSOP-PowerPAD (DGN). The SOIC variant uses standard leadframe; DGN includes thermal pad for enhanced 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 TPS3705-50DR, TPS3808G50DBVR trades watchdog and PFI capability for lower IQ and adjustable threshold, while MAX6326LT45D3+T offers extended temperature range and pin compatibility but no fault-detection extensions - making TPS3705-50DR optimal for new designs needing integrated supervision layers.

Availability

TPS3705-50DR is available at Aetrix Electronics and suitable for industrial programmable controls, automotive body electronics, and portable medical devices requiring stable component supply, long-term lifecycle support, and guaranteed traceability.

Supply support for TPS3705-50DR 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The TPS370x family was designed specifically for microprocessor and DSP power management, integrating reset generation, power-fail warning, and watchdog supervision in a single 8-pin package to reduce system-level complexity and improve reliability.

FAQ

What is the exact V_IT– threshold voltage for TPS3705-50DR?

The TPS3705-50DR has a guaranteed negative-going input threshold voltage (V_IT–) of 4.45 V minimum to 4.65 V maximum over –40°C to 85°C. This 4.55-V nominal value is factory-trimmed for 5-V supply monitoring and includes 70-mV hysteresis to prevent chatter during slow-rising or noisy rails. The specification is validated per TI SLVS184F datasheet Section 7.5.

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

No, TPS3705-50DR does not require an external capacitor for reset timing. Its 200-ms power-on reset delay is internally generated and fixed, eliminating timing component variability and PCB footprint. This is confirmed in the "Features" section of the datasheet and verified in the timing diagram (Figure 7-1), where t_d = 140–280 ms is specified as a device parameter independent of external parts.

How does the watchdog timer in TPS3705-50DR operate?

The TPS3705-50DR watchdog timer times out after 1.1–2.3 s (typical 1.6 s) if no edge transition occurs on the WDI pin. Each rising or falling edge resets the counter. Timeout asserts WDO low and automatically restarts the timer. Leaving WDI unconnected disables the watchdog. This behavior is documented in Section 8.3.3 and Figure 7-1 of the SLVS184F datasheet.

Can TPS3705-50DR monitor a 12-V supply?

Yes, TPS3705-50DR can monitor a 12-V supply using its PFI input with an external resistor divider. The PFI pin accepts up to V_DD + 0.3 V, and the internal comparator trips at 1.2–1.3 V. For 12 V, a 910-kΩ/120-kΩ divider (as shown in Figure 9-1) scales the input to ~1.25 V, matching the PFI threshold. This configuration is validated in the Typical Application section of the datasheet.

What packages are offered for TPS3705-50DR?

TPS3705-50DR is offered in two packages: 8-pin SOIC (D) with body size 3.90 mm × 4.90 mm, and 8-pin MSOP-PowerPAD (DGN) with body size 3.00 mm × 3.00 mm and exposed thermal pad. Both are RoHS-compliant and listed in the Device Information table (Section 1) of the SLVS184F datasheet. The DGN package provides lower thermal resistance (R_θJB = 45.1°C/W) for higher power density layouts.