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STMicroelectronics STM805RM6E
- Part No.:
- STM805RM6E
- Manufacturer:
- STMicroelectronics
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
STM805RM6E.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,282
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Product details
Overview
STM805RM6E from STMicroelectronics is a 3 V microprocessor supervisory IC with active-high open-drain RST output, automatic battery switchover, power-fail comparator (PFI/PFO), and manual reset input (MR). It guarantees reset assertion down to VCC = 1.0 V, features 200 ms typical reset timeout (trec), and draws only 40 µA typical supply current. It is used in industrial embedded systems to safeguard SRAM data during brownout or main power loss.
For engineers reviewing the STM805RM6E datasheet, STM805RM6E pinout, STM805RM6E application, or STM805RM6E equivalent, key selection criteria include its open-drain active-high reset behavior, 2.4 V switchover threshold (VSW), 1.6 s watchdog timeout (tWD), and compatibility with external LPSRAM backup via VOUT/VBAT switching.
Technical Context
The STM805RM6E integrates a precision voltage reference, dual comparators (for VCC monitoring and PFI detection), and an internal trec timer that ensures minimum 200 ms reset pulse width after power-up or fault recovery. Its reset logic asserts RST high when VCC falls below VRST (2.63 V typ) or MR is pulled low - with RST remaining high for trec after recovery.
Battery switchover is implemented via a P-channel MOSFET switch connecting VCC or VBAT to VOUT; VOUT transitions to VBAT when VCC drops below VSW = 2.4 V, enabling continuous LPSRAM power. The PFO output provides early power-fail warning by asserting low when PFI < VPFI (1.25 V typ) or VCC < VSW.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold (VRST) | 2.63 V (typ); ensures reliable MCU reset before VCC drops below safe operating level |
| Switchover Voltage (VSW) | 2.4 V (typ); triggers automatic VOUT source switch from VCC to VBAT during brownout |
| Reset Timeout (trec) | 200 ms (typ); guarantees minimum reset pulse width for full MCU initialization |
| Watchdog Timeout (tWD) | 1.6 s (typ); detects MCU lockup if WDI signal is not toggled within this window |
| Supply Current (ICC) | 40 µA (typ); enables low-power operation in always-on supervisory circuits |
| Battery Supply Current (IBAT) | 0.4 µA (typ); minimizes backup battery drain during extended power-loss periods |
| Operating Temperature | –40 °C to +85 °C; qualified for industrial-grade embedded applications |
Pinout & Package
STM805RM6E is housed in an 8-pin SO8 (Small Outline) package per JEDEC MS-012, with 1.27 mm pitch and surface-mount footprint. Pin 1 is marked with a dot or bevel; device orientation follows standard SO8 pin 1 indexing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PIN 1: PFO | Power-fail output | Push-pull output asserted low when PFI < 1.25 V or VCC < 2.4 V; signals impending power loss |
| PIN 2: VOUT | Supply output for LPSRAM | Switched output connected to VCC or VBAT; powers external low-power SRAM during main power failure |
| PIN 3: VCC | Main supply input | Primary 3 V system supply; monitored for reset assertion and switchover control |
| PIN 4: RST | Active-high open-drain reset output | Open-drain output pulled high externally; drives MCU reset line high during fault or power-up |
| PIN 5: VSS | Ground | Reference node for all internal comparators and logic; must be low-impedance connection |
| PIN 6: MR | Manual reset input | Active-low input with internal 40 kΩ pull-up; initiates reset on button press without external components |
| PIN 7: PFI | Power-fail input | Monitors auxiliary rail or scaled VCC; triggers PFO when voltage drops below 1.25 V threshold |
| PIN 8: VBAT | Backup battery input | Accepts 1.0–5.5 V backup source; automatically supplies VOUT when VCC falls below 2.4 V |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset down to VCC = 1.0 V | Ensures valid reset signaling even during deep brownout, critical for nonvolatile SRAM retention |
| Automatic battery switchover at 2.4 V | Seamlessly transfers VOUT load from VCC to VBAT without glitch or delay, preserving SRAM state |
| Open-drain active-high RST output | Allows wired-OR reset bus configuration and direct interface with 3.3 V or 5 V tolerant MCU inputs |
| Integrated power-fail comparator (PFI/PFO) | Provides early warning of supply collapse ≥100 µs before VCC crosses reset threshold, enabling graceful shutdown |
| 200 ms reset timeout with no external components | Eliminates need for RC timing network, reducing BOM count and improving temperature stability |
Applications
| Industrial PLC Controller | Medical Infusion Pump |
|---|---|
|
Use Scenario: Maintains volatile SRAM contents during AC mains interruption or battery swap. IC Role / Device Role / Timing Role: Supervisory IC providing VOUT switchover, reset assertion, and power-fail warning. Use Value: Prevents therapy parameter loss by sustaining LPSRAM power for >10 seconds using coin-cell backup. |
Use Scenario: Ensures safe shutdown and data logging when primary 3.3 V rail collapses unexpectedly. IC Role / Device Role / Timing Role: Reset generator and early power-fail detector interfacing with ARM Cortex-M4 MCU. Use Value: Triggers EEPROM save sequence within 150 µs of PFO assertion, meeting IEC 62304 Class C requirements. |
| Smart Energy Meter | Ruggedized Handheld Terminal |
|
Use Scenario: Preserves tariff and consumption registers during utility grid flicker or transformer tap change. IC Role / Device Role / Timing Role: Dual-supply supervisor managing VCC/VBAT handoff and watchdog supervision of metering SoC. Use Value: Guarantees 200 ms clean reset pulse and 2.4 V switchover point aligned with metrology ADC reference stability limits. |
Use Scenario: Sustains real-time clock and configuration memory during hot-swap battery replacement in field service. IC Role / Device Role / Timing Role: Battery switchover controller and manual reset handler for i.MX6UL-based terminal. Use Value: Enables zero-downtime battery exchange via VBAT-powered VOUT, eliminating RTC drift or config corruption. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX809SEUR+T | Fixed 3.08 V reset threshold; no battery switchover or PFI/PFO; SOT-23-3 package | Limited to basic reset-only use cases; cannot support SRAM backup or power-fail warning | Select only when minimal footprint and single-function reset are required, and battery backup is unnecessary |
| TPS3808G18DBVR | Adjustable reset threshold (via external resistor); 200 ms trec; no VBAT switchover or PFI input | Suitable for custom reset voltage designs but lacks integrated battery management for LPSRAM | Choose when precise reset threshold tuning is needed and external battery control circuitry already exists |
Compared with MAX809SEUR+T and TPS3808G18DBVR, the STM805RM6E uniquely combines open-drain active-high reset, automatic VCC/VBAT switchover, and PFI/PFO in one SO8 package - making it the only option among the three capable of end-to-end SRAM data retention during power loss without additional discrete components.
Availability
STM805RM6E is available at Aetrix Electronics and suitable for industrial PLC controllers, medical infusion pumps, smart energy meters, and ruggedized handheld terminals requiring stable component supply across extended product lifecycles.
Supply support for STM805RM6E 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 analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.
The STM805 is part of ST's legacy supervisor IC family targeting robust, low-power microprocessor monitoring in space-constrained industrial systems - emphasizing guaranteed reset behavior, battery-backed SRAM support, and RoHS-compliant packaging.
FAQ
What is the function of the Vccsw pin on STM805RM6E?
Vccsw is a push-pull output that indicates VOUT source status: high when VOUT is powered by VBAT, low when powered by VCC. It can drive the gate of an external PMOS transistor to extend VOUT current capability beyond the internal 75 mA limit, enabling higher-load SRAM backup configurations.
Can STM805RM6E be used without a backup battery?
Yes. When no battery is used, connect both VBAT and VOUT directly to VCC. In this configuration, the device operates as a standard 3 V supervisor with reset, watchdog, and power-fail functions - retaining full functionality except battery switchover, which becomes inactive.
Is the RST output truly open-drain, and what pull-up is required?
Yes, RST is an open-drain output requiring an external pull-up resistor. ST recommends 10 kΩ to 100 kΩ to VCC (3.3 V or 5 V), depending on rise time and bus loading. This allows flexible voltage-level translation and wired-OR reset bus implementation with other supervisors or MCUs.
How does the power-fail comparator interact with the reset function?
The PFI/PFO circuit operates independently of the reset comparator: PFO asserts low when PFI < 1.25 V or VCC < 2.4 V, but does not trigger RST. This enables early warning for firmware-initiated shutdown while reserving RST for hard faults like VCC collapse below 2.63 V or manual reset activation.
STM805RM6E Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 2.625V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
STM805RM6E FAQ
1.How can I place an order for STM805RM6E through Aetrix?
Please submit a Request for Quotation (RFQ) for STM805RM6E 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 STM805RM6E reliable?
The price and inventory of STM805RM6E are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for STM805RM6E is usually 5 days.
3.What payment methods are accepted for STM805RM6E?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for STM805RM6E transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for STM805RM6E?
STM805RM6E orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your STM805RM6E 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 STM805RM6E?
For technical support, including STM805RM6E datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your STM805RM6E requirements.
6.How does Aetrix verify that STM805RM6E is sourced from the original manufacturer or authorized distributors?
All STM805RM6E 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 STM805RM6E meets industry standards.
7.What is the process for return or replacement of STM805RM6E?
All STM805RM6E units undergo pre-shipment inspection (PSI). If there is an issue with STM805RM6E, 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 STM805RM6E part is unused and in its original packaging.
Return procedure for STM805RM6E:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
STM805RM6E Tags
-
MIC826SYMT-TR
Microchip Technology
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APX803S-31SA-7
Diodes Incorporated
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APX803L20-29SA-7
Diodes Incorporated
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EM Microelectronic
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EM6325CXSP5B-2.9+
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MCP120T-300I/TT
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MCP130T-315I/TT
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MCP120T-475I/TT
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