Texas Instruments TPS3705-50DGNG4

Overview

TPS3705-50DGNG4 from Texas Instruments is a precision 5-V microprocessor supervisory circuit with integrated watchdog timer, power-fail comparator (PFI/PFO), manual reset (MR), and fixed 200-ms power-on reset delay. It monitors VDD ≥ 1.1 V, asserts active-low RESET below 4.55 V threshold (±20 mV hysteresis), and delivers <50 µA supply current over –40°C to 85°C - used in MSP430-based embedded systems requiring reliable boot sequencing and brownout protection.

For engineers reviewing the TPS3705-50DGNG4 datasheet, TPS3705-50DGNG4 pinout, TPS3705-50DGNG4 application, or TPS3705-50DGNG4 equivalent, key selection criteria include its 4.55-V VIT– threshold, 1.6-s watchdog timeout, dual-supply monitoring capability (VDD + PFI), MSOP-PowerPAD™ 8-pin package, and compatibility with MAX705–MAX708-series designs.

Technical Context

The TPS3705-50DGNG4 implements a dual-comparator architecture: one for VDD supervision (with internal 1.25-V reference and resistor divider) and a second for independent PFI voltage monitoring. Its watchdog logic triggers on WDI edge transitions and times out after 1.6 s (typical) if unrefreshed, asserting WDO low.

RESET assertion occurs at VDD < 4.55 V (VIT–) with 70-mV hysteresis; power-up reset initiates when VDD exceeds 1.1 V and holds for 200 ms. All timing and thresholds are internally fixed - no external capacitors or resistors required for basic operation.

Key Specifications

Pinout & Package

TPS3705-50DGNG4 is packaged in an 8-pin MSOP-PowerPAD™ (DGN) with 3.00 mm × 3.00 mm body size and exposed thermal pad. Pin 1 is RESET; pin 8 is WDI. The PowerPAD enhances thermal performance (RθJB = 45.1°C/W) and requires PCB solder connection for optimal reliability.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supervisory circuit applications.

Compared with TPS3705-50DGNG4, TPS3705-50D offers identical functionality in a larger, thermally less efficient package, while MAX706CSA+ provides baseline reset capability without watchdog or power-fail monitoring - making TPS3705-50DGNG4 the only option supporting full three-function supervision in a thermally optimized 3×3 mm footprint.

Availability

TPS3705-50DGNG4 is available at Aetrix Electronics and suitable for industrial PLC controllers, battery-powered data loggers, automotive body control modules, and notebook embedded controller power management requiring stable component supply and long-term manufacturability.

Supply support for TPS3705-50DGNG4 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 ICs, with decades of expertise in high-reliability supervisory circuits.

The TPS370x family was designed specifically for robust microprocessor supervision in harsh environments - delivering precision voltage monitoring, watchdog safety, and power-fail warning in minimal footprint packages like the TPS3705-50DGNG4.

FAQ

What is the exact VDD reset threshold voltage for TPS3705-50DGNG4?

The TPS3705-50DGNG4 has a nominal negative-going VDD threshold (VIT–) of 4.55 V, with a tolerance of ±20 mV over –40°C to 85°C. This value is factory-trimmed and specified in Section 7.5 of the datasheet. It is distinct from the 5-V nominal supply - the device asserts RESET when VDD drops below this precise threshold to ensure clean brownout response.

Does TPS3705-50DGNG4 require external components to operate?

No, the TPS3705-50DGNG4 operates autonomously with no external timing components. Its 200-ms reset delay, 4.55-V threshold, and 1.6-s watchdog timeout are fully internal. A 0.1-µF ceramic decoupling capacitor on VDD is recommended per Section 11.1, but it is not functionally required for basic reset generation.

How does the watchdog timer in TPS3705-50DGNG4 function?

The TPS3705-50DGNG4 watchdog timer resets on any edge (rising or falling) at WDI. If no transition occurs within 1.6 s (typical), WDO goes low. This signal can trigger an NMI or reset in the host MCU. Leaving WDI unconnected disables the watchdog - no pull-up/down is needed.

Can TPS3705-50DGNG4 monitor a 12-V supply?

Yes - the PFI input accepts voltages up to VDD + 0.3 V and uses an internal 1.25-V comparator threshold. To monitor 12 V, connect it to PFI through a resistor divider (e.g., 910 kΩ + 120 kΩ as shown in Figure 9-1), scaling 12 V down to ~1.25 V at PFI for accurate power-fail detection.

Is TPS3705-50DGNG4 pin-compatible with MAX705–MAX708 devices?

Yes - the TPS3705-50DGNG4 is explicitly stated in the datasheet (Section 1) as pin-for-pin compatible with the MAX705 through MAX708 series *in the same package variant*. However, note that MAX705–MAX708 are only offered in SOIC-8, while TPS3705-50DGNG4 is MSOP-PowerPAD™ - direct replacement requires matching package type or board redesign.