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STMicroelectronics SR1PAAU
- Part No.:
- SR1PAAU
- Manufacturer:
- STMicroelectronics
- Category:
- Supervisors
- Package:
- 6-UDFN
- Datasheet:
-
SR1PAAU.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 6UDFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,695
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Product details
Overview
SR1PAAU from STMicroelectronics is a 4-pin Smart Reset™ supervisory IC with factory-programmed 7.5 s Smart Reset delay (tSRC), 210 ms fixed reset pulse duration (tREC), active-low open-drain RST output, and active-low SR input without internal pull-up. It operates from 2 V to 5.5 V, draws only 1 µA supply current, and is qualified for -40 °C to +85 °C ambient. Used in wearable electronics to replace mechanical reset buttons while preventing spurious resets.
For engineers reviewing the SR1PAAU datasheet, SR1PAAU pinout, SR1PAAU application, or SR1PAAU equivalent, key selection criteria include tSRC/tREC timing precision, open-drain RST drive capability, undervoltage-safe high-Z behavior, and UDFN6 footprint compatibility with space-constrained wearables.
Technical Context
The SR1PAAU implements a deterministic two-stage reset logic: first, an extended setup delay (tSRC = 7.5 s typ.) filters short button presses; second, a factory-fixed reset assertion time (tREC = 210 ms typ.) guarantees system-level recovery regardless of push-button release timing. Its test mode entry requires overvoltage on SR (VCC + 0.9–1.4 V), enabling in-system validation without external hardware.
It supports mixed-voltage domain operation via fixed SR input thresholds and open-drain RST with optional internal pull-up. The device guarantees high-Z RST output during VCC power-up or brownout, eliminating false resets during supply ramping - critical for battery-powered wearables with variable VBAT profiles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| tSRC delay | 7.5 s typical; factory-programmed fixed delay prevents accidental reset from brief button presses. |
| tREC pulse width | 210 ms typical; ensures minimum reset assertion time independent of user release timing. |
| VCC range | 2.0 V to 5.5 V; supports single-cell Li-ion (3.0–4.2 V) and dual-cell alkaline (2.4–3.2 V) systems. |
| ICC supply current | 1 µA typical at VCC = 3.3 V; enables multi-year battery life in always-on wearables. |
| Package | UDFN6 (1.00 mm × 1.45 mm × 0.50 mm); 0.5 mm pitch, footprint-optimized for compact PCBs. |
| Operating temp | -40 °C to +85 °C; validated for wrist-worn devices exposed to body heat and ambient temperature swings. |
| Reset output | Active-low open-drain RST; compatible with 1.8 V–5 V MCU reset inputs via external or internal pull-up. |
Pinout & Package
SR1PAAU is housed in a 6-pin UDFN package (1.00 mm × 1.45 mm, 0.50 mm pitch) with two unused pins (NC) bonded but electrically isolated and recommended to be connected to VSS for thermal and EMI stability.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 | RST | Active-low open-drain reset output; requires external or internal pull-up to define logic high level. |
| 2 | VSS | Ground reference for all internal circuitry; must be low-impedance connection to system ground plane. |
| 3 | SR | Active-low Smart Reset input; no internal pull-up (per 'A' in part number); requires external pull-up or MCU-driven signal. |
| 4 | VCC | Positive supply input; requires 0.1 µF ceramic decoupling capacitor placed adjacent to pin. |
| 5 | NC | Not connected (not bonded); electrically floating but recommended to tie to VSS for mechanical stability. |
| 6 | NC | Not connected (not bonded); electrically floating but recommended to tie to VSS for mechanical stability. |
Key Features
| Feature | Design Value |
|---|---|
| Smart Reset delay (tSRC) | Factory-programmed 7.5 s typ. eliminates need for dedicated reset button and prevents accidental resets. |
| Fixed reset pulse (tREC) | 210 ms typ. ensures reliable processor reset completion even if user releases button prematurely. |
| Test mode entry | Voltage > VCC + 0.9 V on SR pin enables in-circuit verification without additional test fixtures. |
| Undervoltage-safe RST | Guaranteed high-Z state below 2.0 V prevents false resets during power-up or brownout conditions. |
| Low-power operation | 1 µA ICC enables integration into ultra-low-power wearable subsystems without impacting battery budget. |
Applications
| Activity Tracker | Smartwatch |
|---|---|
|
Use Scenario: User holds side button for >7 s to force full system reboot after firmware hang. IC Role / Device Role / Timing Role: Supervisory IC providing tSRC-filtered reset initiation and tREC-guaranteed reset assertion. Use Value: Eliminates need for separate reset microcontroller or complex GPIO debouncing firmware. |
Use Scenario: Recovery from display freeze during Bluetooth pairing failure. IC Role / Device Role / Timing Role: Hardware-enforced reset sequencer ensuring MCU reset occurs only after confirmed long-press. Use Value: Prevents unintended reboots from accidental button taps during daily wear. |
| Smartglasses | Fitness Band |
|
Use Scenario: Forced restart after sensor fusion algorithm lockup during AR overlay rendering. IC Role / Device Role / Timing Role: Standalone reset controller interfacing between tactile switch and ARM Cortex-M reset pin. Use Value: Reduces BOM count by replacing discrete RC+Schmitt trigger reset circuit with integrated solution. |
Use Scenario: Recovery from BLE stack deadlock during firmware OTA update. IC Role / Device Role / Timing Role: Voltage-agnostic reset generator supporting both 3.3 V MCU and 1.8 V sensor hub domains. Use Value: Enables shared reset button across multiple voltage islands without level-shifter components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar Smart Reset applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX6326TUT+T | Fixed 1.25 s reset timeout; no programmable tSRC; push-pull RST output only. | Lacks extended Smart Reset logic; suitable only for basic power-on reset, not user-initiated recovery. | Select when tREC-only timing suffices and board layout cannot accommodate open-drain pull-up. |
| TPS3808G12DBVR | Adjustable tRESET via external capacitor; no tSRC logic; requires external RC network for delay tuning. | Demands layout area and component tolerance management; less precise than factory-programmed tSRC. | Choose if design requires field-adjustable reset timing and accepts added bill-of-materials complexity. |
Compared with MAX6326TUT+T and TPS3808G12DBVR, SR1PAAU uniquely delivers factory-trimmed 7.5 s tSRC + 210 ms tREC in a 1.45 mm footprint, enabling robust user-triggered recovery without calibration or external components.
Availability
SR1PAAU is available at Aetrix Electronics and suitable for wearable electronics, activity trackers, and smartwatches requiring stable component supply with guaranteed long-term production continuity.
Supply support for SR1PAAU 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
STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog products for industrial, automotive, and consumer markets.
SR1PAAU belongs to ST's Smart Reset™ family - purpose-built for space-constrained portable electronics needing reliable, user-initiated system recovery without firmware dependency or mechanical button wear-out.
FAQ
What is the exact tSRC and tREC timing for SR1PAAU?
The SR1PAAU has a factory-programmed Smart Reset delay (tSRC) of 7.5 seconds typical, with ±20% variation over temperature (-40 °C to +85 °C). Its reset output pulse duration (tREC) is fixed at 210 ms typical, with min/max values of 140 ms and 280 ms respectively, per datasheet Table 4.
Does SR1PAAU require an external pull-up resistor on the SR input?
Yes - the 'A' in SR1PAAU indicates active-low SR input with no internal pull-up resistor. An external pull-up (typically 10–100 kΩ to VCC) is required to ensure proper logic-high idle state and enable clean low-going edge detection on button press.
Can SR1PAAU operate reliably during battery voltage sag?
Yes - the device guarantees high-Z (tri-state) behavior on the RST output when VCC drops below 2.0 V, preventing false resets during brownout. Its operating range starts at 2.0 V, and it maintains valid tSRC/tREC timing down to that threshold.
How is test mode triggered and verified on SR1PAAU?
Test mode is entered by applying ≥ VCC + 0.9 V to the SR pin (e.g., 4.2 V when VCC = 3.3 V). Entry is confirmed by observing RST go low for tSRC-INI (42 ms typ.). Releasing SR returns to normal mode only after full VCC power cycle - no software reset suffices.
SR1PAAU Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- Smart Reset™
- Package/Case:
- 6-UDFN
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Reset Timer
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- Adjustable/Selectable
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-UDFN (1.45x1)
SR1PAAU FAQ
1.How can I place an order for SR1PAAU through Aetrix?
Please submit a Request for Quotation (RFQ) for SR1PAAU 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 SR1PAAU reliable?
The price and inventory of SR1PAAU are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for SR1PAAU is usually 5 days.
3.What payment methods are accepted for SR1PAAU?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for SR1PAAU transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for SR1PAAU?
SR1PAAU orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your SR1PAAU 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 SR1PAAU?
For technical support, including SR1PAAU datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your SR1PAAU requirements.
6.How does Aetrix verify that SR1PAAU is sourced from the original manufacturer or authorized distributors?
All SR1PAAU 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 SR1PAAU meets industry standards.
7.What is the process for return or replacement of SR1PAAU?
All SR1PAAU units undergo pre-shipment inspection (PSI). If there is an issue with SR1PAAU, 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 SR1PAAU part is unused and in its original packaging.
Return procedure for SR1PAAU:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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