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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Supervisors

Texas Instruments TPS3705-33DRG4

Name: TPS3705-33DRG4
Brand: Texas Instruments
SKU: TPS3705-33DRG4
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: TPS3705-33DRG4

Manufacturer:: Texas Instruments

Category:: Supervisors

Package:: 8-SOIC (0.154", 3.90mm Width)

Datasheet:: TPS3705-33DRG4.pdf

Description:: IC SUPERVISOR 1 CHANNEL 8SOIC

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Product details

Overview

TPS3705-33DRG4 from Texas Instruments is a precision 3.3 V supply-voltage supervisor IC with integrated watchdog timer, power-fail comparator, and 200 ms power-on reset delay. It monitors V_DD for brownout (V_IT– = 2.93 V), asserts active-low RESET during undervoltage or manual reset, and provides WDO timeout at 1.6 s. Used in microcontroller-based industrial controllers requiring extended temperature operation.

For engineers reviewing the TPS3705-33DRG4 datasheet, TPS3705-33DRG4 pinout, TPS3705-33DRG4 application, or TPS3705-33DRG4 equivalent, key selection criteria include its –40°C to 125°C operating range, 50 µA max supply current, 8-pin SOIC package, and watchdog timer functionality not present in TPS3707 variants.

Technical Context

The TPS3705-33DRG4 implements dual supervision: a precision bandgap-referenced V_DD monitor with 50 mV hysteresis and a separate PFI/PFO comparator for auxiliary rail monitoring. Its internal watchdog timer requires periodic WDI transitions and triggers WDO after 1.6 s timeout-enabling system-level fault recovery without external timing components.

RESET assertion occurs when V_DD falls below 2.93 V (–40°C to 125°C) or rises above 1.1 V at power-up, with fixed 200 ms delay before deassertion. MR input provides asynchronous reset control, while PFI accepts externally scaled voltages for secondary supply monitoring down to 1.25 V threshold.

Key Specifications

Parameter	Value and Actual Design Meaning
V_IT– Threshold	2.93 V (±70 mV over –40°C to 125°C); ensures reliable 3.3 V rail supervision with margin against noise-induced false resets
Reset Delay	200 ms fixed; eliminates need for external capacitor and guarantees sufficient processor initialization time
Watchdog Timeout	1.6 s typical; enables firmware crash detection and automatic system recovery without MCU intervention
Supply Current	50 µA max; supports low-power battery-backed systems and extends runtime in portable equipment
Operating Temp	–40°C to 125°C; qualified for under-hood automotive and high-ambient industrial environments
PFI Threshold	1.25 V (±50 mV); allows flexible scaling of secondary supplies (e.g., 12 V, 5 V) using resistor dividers
Output Drive	1 mA sink capability on RESET; directly interfaces with standard CMOS inputs without pull-up resistors

Pinout & Package

TPS3705-33DRG4 is packaged in an 8-pin SOIC (D package) with 3.90 mm × 4.90 mm body size and standard 1.27 mm lead pitch.

Pin/Terminal	Circuit Role	Design Meaning
MR (Pin 1)	Manual Reset Input	Active-low asynchronous reset trigger; pulls RESET low immediately upon logic-low assertion
V_DD (Pin 2)	Supply Voltage Input	Primary 2–6 V power source; powers internal reference, comparators, and watchdog oscillator
GND (Pin 3)	Ground Reference	Common return path for all internal circuits and output drivers; requires low-impedance PCB connection
PFI (Pin 4)	Power-Fail Input	Analog input for secondary supply monitoring; threshold set by internal 1.25 V reference
PFO (Pin 5)	Power-Fail Output	Active-low open-drain output signaling auxiliary supply undervoltage; requires external pull-up
WDI (Pin 6)	Watchdog Input	Edge-sensitive input; rising or falling transition resets watchdog timer; unconnected disables function
RESET (Pin 7)	Reset Output	Active-low open-drain reset signal; asserts during V_DD undervoltage, MR assertion, or watchdog timeout
WDO (Pin 8)	Watchdog Output	Active-low open-drain watchdog timeout signal; independent of RESET and usable for system diagnostics

Key Features

Feature	Design Value
Integrated Watchdog Timer	1.6 s timeout with edge-triggered WDI; eliminates external RC timing network and reduces BOM count
Fixed 200 ms Reset Delay	No external capacitor required; ensures consistent, repeatable processor boot timing across units and temperatures
Wide Temperature Range	–40°C to 125°C operation; supports automotive engine control modules and industrial PLCs without derating
Dual Supervision Capability	Simultaneous V_DD monitoring and PFI-based auxiliary rail supervision; enables single-chip multi-rail system health checks
Low Quiescent Current	50 µA max supply draw; minimizes impact on battery life in always-on sensor nodes and backup power circuits

Applications

Industrial Programmable Logic Controllers	Automotive Engine Control Units
Use Scenario: Monitoring 3.3 V microcontroller supply and 12 V fuel pump driver rail in harsh factory-floor environments. IC Role / Device Role / Timing Role: Primary V_DD supervisor and secondary PFI-based power-fail detector; generates RESET on main rail collapse and PFO on auxiliary rail sag. Use Value: Prevents erratic PLC operation during voltage transients; enables safe shutdown sequencing via PFO-triggered relay control.	Use Scenario: Supervising 3.3 V ECU microcontroller and 5 V sensor interface supply in under-hood locations. IC Role / Device Role / Timing Role: Dual-rail supervisor with watchdog; asserts RESET on V_DD brownout and triggers WDO if firmware hangs during CAN message processing. Use Value: Meets ISO 16750-2 pulse test requirements; watchdog recovery avoids limp-home mode entry due to software lockup.
Portable Medical Diagnostic Devices	Smart Energy Meters
Use Scenario: Ensuring reliable boot and runtime integrity of ARM Cortex-M4 processor powered from Li-ion battery with 3.3 V LDO. IC Role / Device Role / Timing Role: Power-on reset generator and low-battery warning detector; uses PFI to monitor battery voltage via divider. Use Value: 200 ms fixed delay guarantees full RAM initialization; PFO alert enables graceful data save before shutdown.	Use Scenario: Supervising 3.3 V metrology SoC and 5 V isolated RS-485 transceiver in utility-grade meters. IC Role / Device Role / Timing Role: Main supply supervisor with watchdog; RESET holds SoC in reset during AC line dropout; WDO flags firmware stalls during tariff calculation. Use Value: Maintains meter accuracy certification (IEC 62053) by preventing corrupted energy accumulation during brownouts.

Industrial Programmable Logic Controllers

Automotive Engine Control Units

Use Scenario: Monitoring 3.3 V microcontroller supply and 12 V fuel pump driver rail in harsh factory-floor environments.

IC Role / Device Role / Timing Role: Primary V_DD supervisor and secondary PFI-based power-fail detector; generates RESET on main rail collapse and PFO on auxiliary rail sag.

Use Value: Prevents erratic PLC operation during voltage transients; enables safe shutdown sequencing via PFO-triggered relay control.

Use Scenario: Supervising 3.3 V ECU microcontroller and 5 V sensor interface supply in under-hood locations.

IC Role / Device Role / Timing Role: Dual-rail supervisor with watchdog; asserts RESET on V_DD brownout and triggers WDO if firmware hangs during CAN message processing.

Use Value: Meets ISO 16750-2 pulse test requirements; watchdog recovery avoids limp-home mode entry due to software lockup.

Portable Medical Diagnostic Devices

Smart Energy Meters

Use Scenario: Ensuring reliable boot and runtime integrity of ARM Cortex-M4 processor powered from Li-ion battery with 3.3 V LDO.

IC Role / Device Role / Timing Role: Power-on reset generator and low-battery warning detector; uses PFI to monitor battery voltage via divider.

Use Value: 200 ms fixed delay guarantees full RAM initialization; PFO alert enables graceful data save before shutdown.

Use Scenario: Supervising 3.3 V metrology SoC and 5 V isolated RS-485 transceiver in utility-grade meters.

IC Role / Device Role / Timing Role: Main supply supervisor with watchdog; RESET holds SoC in reset during AC line dropout; WDO flags firmware stalls during tariff calculation.

Use Value: Maintains meter accuracy certification (IEC 62053) by preventing corrupted energy accumulation during brownouts.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
TPS3705-33D	Same silicon, identical electrical specs and pinout; D suffix denotes SOIC package without Green/ROHS designation	No functional difference; D variant lacks halogen-free marking but shares full qualification	Select TPS3705-33D only if RoHS exemption applies; otherwise TPS3705-33DRG4 preferred for compliance
MAX706TSA+	Pin-compatible MAXIM part; 3.08 V threshold, 200 ms delay, no watchdog timer, 125°C max temp	Lacks WDI/WDO functionality; requires external circuitry for watchdog behavior	Choose MAX706TSA+ only when watchdog is unnecessary and legacy MAX705-series compatibility is mandatory

Compared with TPS3705-33D and MAX706TSA+, the TPS3705-33DRG4 uniquely combines 125°C operation, integrated watchdog, and RoHS compliance in a single SOIC package-enabling simplified design for safety-critical embedded systems without trade-offs in temperature or functionality.

Availability

TPS3705-33DRG4 is available at Aetrix Electronics and suitable for industrial programmable controllers, automotive engine management systems, and portable medical devices requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TPS3705-33DRG4 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 over 90 years of innovation history.

The TPS370x family was designed specifically for robust microprocessor supervision in demanding environments-delivering precision voltage monitoring, watchdog protection, and power-fail detection in compact packages for automotive, industrial, and medical applications.

FAQ

What is the exact reset threshold voltage for TPS3705-33DRG4 over its full temperature range?

The TPS3705-33DRG4 has a guaranteed negative-going input threshold voltage (V_IT–) of 2.87 V minimum to 3.02 V maximum across –40°C to 125°C, with 2.93 V nominal. This 50 mV hysteresis prevents chatter during slow voltage transitions and ensures reliable 3.3 V rail supervision under thermal stress.

Does TPS3705-33DRG4 require an external capacitor for reset timing?

No, the TPS3705-33DRG4 features an internal 200 ms power-on reset delay generator with no external components required. This eliminates capacitor tolerance, aging, and temperature drift concerns-ensuring consistent reset timing across production lots and environmental conditions for the TPS3705-33DRG4.

How does the watchdog timer in TPS3705-33DRG4 function, and what is its timeout period?

TPS3705-33DRG4's watchdog timer resets on any rising or falling edge at WDI and times out after 1.6 s (typical) if no transition occurs. Upon timeout, WDO asserts low and automatically restarts the timer. Leaving WDI unconnected disables the watchdog, making it fully configurable per system needs for the TPS3705-33DRG4.

Can TPS3705-33DRG4 monitor a 12 V supply, and how is that implemented?

Yes, TPS3705-33DRG4 monitors auxiliary supplies like 12 V using the PFI input with an external resistor divider. The internal 1.25 V reference sets the PFI threshold; for 12 V monitoring, a 910 kΩ/120 kΩ divider scales it to 1.25 V at PFI, triggering PFO when input drops below ~11.3 V-enabling dual-rail supervision in the TPS3705-33DRG4.

What is the maximum operating temperature specification for TPS3705-33DRG4?

The TPS3705-33DRG4 is fully specified from –40°C to 125°C ambient temperature, validated per TI's SLVS184F datasheet revision F (October 2020). This extended range exceeds standard industrial grade and qualifies the TPS3705-33DRG4 for under-hood automotive, motor drive, and high-temperature industrial control applications.

TPS3705-33DRG4 Specifications

Product attributes: Attribute value

Manufacturer:: Texas Instruments

Series:: -

Package/Case:: 8-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Discontinued at Digi-Key

Programmable:: Not Verified

Type:: Simple Reset/Power-On Reset

Number of Voltages Monitored:: 1

Voltage - Threshold:: 2.93V

Output:: Push-Pull, Totem Pole

Reset:: Active Low

Reset Timeout:: 140ms Minimum

Operating Temperature:: -40°C ~ 85°C (TA)

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 8-SOIC

TPS3705-33DRG4 FAQ

1.How can I place an order for TPS3705-33DRG4 through Aetrix?

Please submit a Request for Quotation (RFQ) for TPS3705-33DRG4 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for TPS3705-33DRG4 reliable?

The price and inventory of TPS3705-33DRG4 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TPS3705-33DRG4 is usually 5 days.

3.What payment methods are accepted for TPS3705-33DRG4?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TPS3705-33DRG4 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for TPS3705-33DRG4?

TPS3705-33DRG4 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your TPS3705-33DRG4 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for TPS3705-33DRG4?

For technical support, including TPS3705-33DRG4 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TPS3705-33DRG4 requirements.

6.How does Aetrix verify that TPS3705-33DRG4 is sourced from the original manufacturer or authorized distributors?

All TPS3705-33DRG4 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TPS3705-33DRG4 meets industry standards.

7.What is the process for return or replacement of TPS3705-33DRG4?

All TPS3705-33DRG4 units undergo pre-shipment inspection (PSI). If there is an issue with TPS3705-33DRG4, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The TPS3705-33DRG4 part is unused and in its original packaging.

Return procedure for TPS3705-33DRG4:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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