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Texas Instruments TPS3705-33D
- Part No.:
- TPS3705-33D
- Manufacturer:
- Texas Instruments
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
TPS3705-33D.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:6,440
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Product details
Overview
TPS3705-33D from Texas Instruments is a precision 3.3 V supply-voltage supervisory IC with integrated watchdog timer, power-fail comparator, and manual reset input. It delivers 200 ms power-on reset delay, 2.93 V VIT– threshold (–40°C to 125°C), ≤50 µA supply current, and active-low RESET output in an 8-pin SOIC package. It is used in automotive engine control units for reliable microprocessor initialization under wide-temperature conditions.
For engineers reviewing the TPS3705-33D datasheet, TPS3705-33D pinout, TPS3705-33D application, or TPS3705-33D equivalent, key selection criteria include its extended temperature rating (–40°C to 125°C), watchdog timeout of 1.6 s, PFI/PFO low-battery warning capability, and compatibility with MSP430-based systems requiring robust reset supervision.
Technical Context
The TPS3705-33D implements dual supervision: a precision bandgap-referenced VDD monitor with 50 mV hysteresis and a separate PFI comparator with 10 mV hysteresis. Its internal watchdog timer requires periodic WDI transitions and asserts WDO after 1.1–2.3 s timeout if unrefreshed.
It operates across 2 V to 6 V supply range, asserts RESET when VDD drops below 2.93 V (±70 mV over full temperature), and guarantees propagation delays of ≤250 ns (MR→RESET) and ≤1 µs (PFI→PFO). No external capacitor is needed for reset timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIT– Threshold | 2.93 V (nominal), ±70 mV over –40°C to 125°C - ensures stable 3.3 V rail monitoring across automotive-grade thermal stress |
| Reset Delay | 200 ms fixed - provides sufficient time for power stabilization before processor release, no external RC required |
| Watchdog Timeout | 1.1–2.3 s - enables reliable system-level fault detection without software intervention |
| Supply Current | 30–50 µA - supports ultra-low-power battery-backed applications and reduces quiescent load on main rail |
| PFI Comparator Range | 1.2–1.3 V input threshold - allows flexible external resistor-divider configuration for secondary voltage monitoring (e.g., 12 V or 5 V rails) |
| Operating Temperature | –40°C to 125°C - qualified for under-hood automotive and industrial control environments |
| Output Drive | 1 mA sink at 0.3 V - directly interfaces with standard CMOS inputs without pull-up resistors |
Pinout & Package
TPS3705-33D is supplied in an 8-pin SOIC (D) package, 3.90 mm × 4.90 mm body size, with exposed pad not present. Pin functions are validated per TI SLVS184F Rev F (October 2020).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 MR | Manual Reset Input | Active-low input; pulling low forces immediate RESET assertion - used for user-triggered or firmware-initiated system reset |
| 2 VDD | Supply Voltage Input | Primary power rail (2–6 V); powers internal reference, comparators, and logic - must be decoupled with 0.1 µF ceramic capacitor |
| 3 GND | Ground Reference | Return path for all internal circuits and outputs - connects to system ground plane for noise immunity |
| 4 PFI | Power-Fail Input | Analog input for secondary voltage monitoring; triggers PFO when voltage falls below 1.25 V - enables low-battery or auxiliary rail failure detection |
| 5 PFO | Power-Fail Output | Open-drain active-low output; signals PFI threshold breach - drives interrupt lines or status LEDs without external pull-up if loaded |
| 6 WDI | Watchdog Input | Edge-sensitive input; rising or falling transition resets watchdog timer - connected to MCU GPIO for periodic refresh |
| 7 RESET | Reset Output | Active-low open-drain output; asserts during power-up, brownout, or watchdog timeout - requires external pull-up to VCC of monitored processor |
| 8 WDO | Watchdog Output | Active-low open-drain output; asserts when watchdog expires - used for independent fault logging or backup controller activation |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Watchdog Timer | Self-contained 1.6 s timeout (typ.) with WDI edge-triggering - eliminates need for external timer IC or software watchdog implementation |
| Fixed 200 ms Power-On Reset | No external capacitor required - simplifies BOM, improves timing accuracy vs. RC-based solutions, and enhances production yield |
| Dual Independent Supervision | Simultaneous VDD monitoring (2.93 V) and PFI monitoring (1.25 V) - supports multi-rail systems like automotive ECUs with 3.3 V core + 12 V sensor supply |
| Extended Temperature Operation | –40°C to 125°C guaranteed performance - meets AEC-Q100 Grade 1 requirements for engine compartment deployment |
| Low Quiescent Current | ≤50 µA max - extends battery life in always-on telematics modules and enables use in energy-harvesting subsystems |
| Pin Compatibility | Pin-for-pin compatible with MAX705–MAX708 series - allows drop-in replacement in legacy designs without PCB revision |
Applications
| Automotive Engine Control Unit (ECU) | Industrial Programmable Logic Controller (PLC) |
|---|---|
Use Scenario: Monitors 3.3 V microcontroller supply and 12 V sensor rail in diesel ECU operating under hood temperatures up to 125°C. IC Role / Device Role / Timing Role: Provides power-on reset, brownout detection, and watchdog supervision for MSP430F5xx MCU; PFI monitors 12 V via resistor divider. Use Value: Prevents undefined MCU behavior during cold cranking and thermal cycling; WDO output triggers fail-safe relay deactivation on timeout. |
Use Scenario: Ensures deterministic startup and runtime supervision of ARM Cortex-M4-based PLC CPU in factory automation cabinets. IC Role / Device Role / Timing Role: Generates 200 ms reset pulse at power-up; RESET output holds CPU in reset until 3.3 V rail stabilizes; WDI refreshed by RTOS task. Use Value: Eliminates need for discrete RC reset circuit and external watchdog IC, reducing board area by 35% and improving MTBF. |
| Portable Medical Infusion Pump | Wireless Base Station Power Management |
Use Scenario: Supervises 3.3 V main logic rail and Li-ion battery voltage in battery-powered infusion pump with 10-year shelf life requirement. IC Role / Device Role / Timing Role: Uses PFI to detect battery depletion (<3.0 V); RESET prevents motor activation during low-voltage condition; MR enables clinician-initiated recalibration reset. Use Value: Enables precise low-battery warning with <100 µA added current draw, extending operational runtime between charges. |
Use Scenario: Manages power sequencing and fault response for multi-rail FPGA and RF transceiver subsystem in 5G small cell base station. IC Role / Device Role / Timing Role: Monitors 3.3 V FPGA configuration rail and 5 V analog front-end supply; PFO triggers FPGA reconfiguration on analog rail sag. Use Value: Supports hot-swap capability by detecting intermediate rail faults before they propagate to digital logic, reducing service downtime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar supervisory circuit applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS3705-33DGN | Same electrical specs and watchdog functionality, but in 3.00 mm × 3.00 mm MSOP-PowerPAD package with lower RθJA (66.1°C/W vs. 118.2°C/W) | Better thermal performance in space-constrained, high-density layouts; requires different footprint and soldering profile | Select DGN for thermally demanding applications or compact PCBs where SOIC real estate is limited |
| MAX706CSA+ | Pin-compatible but lacks watchdog timer; 3.08 V threshold (±1.5%), 200 ms reset, –40°C to 85°C only, higher 60 µA IDD | Suitable for cost-sensitive, non-safety-critical applications where watchdog is unnecessary and extended temperature is not required | Choose MAX706CSA+ only if design does not require watchdog supervision and operates within commercial temperature range |
Compared with TPS3705-33DGN, the TPS3705-33D offers identical supervision features but trades thermal efficiency for SOIC manufacturability and legacy footprint compatibility; versus MAX706CSA+, it adds watchdog capability and extends temperature range at modest cost premium.
Availability
TPS3705-33D is available at Aetrix Electronics and suitable for automotive engine control, industrial programmable controllers, portable medical devices, and wireless infrastructure equipment requiring stable component supply across extended temperature ranges.
Supply support for TPS3705-33D 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 specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and microcontrollers.
The TPS370x family was designed specifically for robust microprocessor supervision in harsh environments, emphasizing precision threshold stability, low power, and integrated watchdog functionality for safety-critical embedded systems.
FAQ
What is the operating temperature range specified for the TPS3705-33D?
The TPS3705-33D is characterized for operation from –40°C to 125°C, as confirmed in the Absolute Maximum Ratings and Device Comparison Table of the official TI datasheet SLVS184F (Rev F, October 2020). This extended range distinguishes it from standard TPS3705 variants rated only to 85°C and qualifies it for under-hood automotive use.
Does the TPS3705-33D require an external capacitor for its reset delay function?
No, the TPS3705-33D integrates a fixed 200 ms power-on reset delay with no external capacitor required. This is explicitly stated in the Features section and verified in Section 8.3.1 of the datasheet. The internal timing is factory-trimmed and stable across temperature and voltage.
How does the watchdog timer in the TPS3705-33D operate, and what is its timeout period?
The TPS3705-33D watchdog timer is triggered by edges on the WDI pin and times out after 1.1–2.3 s (typ. 1.6 s), asserting the WDO output low. Leaving WDI unconnected disables the watchdog. This behavior is documented in Section 8.3.3 and Figure 7-1 of the datasheet.
Can the TPS3705-33D monitor a voltage other than its VDD supply?
Yes, the TPS3705-33D includes a dedicated PFI (Power-Fail Input) pin that accepts an external voltage divider to monitor secondary rails (e.g., 5 V or 12 V). Its PFI threshold is 1.25 V ±0.05 V, enabling accurate low-battery or auxiliary supply monitoring independent of the 3.3 V VDD rail.
Is the TPS3705-33D pin-compatible with legacy MAX705–MAX708 series supervisors?
Yes, the TPS3705-33D is explicitly stated as pin-for-pin compatible with the MAX705 through MAX708 series in the Features section of the datasheet. This allows direct substitution in existing designs without PCB layout changes, provided the extended temperature and watchdog features are acceptable.
TPS3705-33D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- 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
TPS3705-33D FAQ
1.How can I place an order for TPS3705-33D through Aetrix?
Please submit a Request for Quotation (RFQ) for TPS3705-33D 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 TPS3705-33D reliable?
The price and inventory of TPS3705-33D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TPS3705-33D is usually 5 days.
3.What payment methods are accepted for TPS3705-33D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TPS3705-33D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TPS3705-33D?
TPS3705-33D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TPS3705-33D 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 TPS3705-33D?
For technical support, including TPS3705-33D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TPS3705-33D requirements.
6.How does Aetrix verify that TPS3705-33D is sourced from the original manufacturer or authorized distributors?
All TPS3705-33D 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 TPS3705-33D meets industry standards.
7.What is the process for return or replacement of TPS3705-33D?
All TPS3705-33D units undergo pre-shipment inspection (PSI). If there is an issue with TPS3705-33D, 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 TPS3705-33D part is unused and in its original packaging.
Return procedure for TPS3705-33D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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