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Analog Devices Inc. LTC694IN8#PBF
- Part No.:
- LTC694IN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LTC694IN8#PBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,204
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Product details
Overview
LTC694IN8#PBF from Analog Devices (formerly Linear Technology) is an 8-pin microprocessor supervisory IC providing guaranteed reset assertion down to VCC = 1V, 4.65V precision power supply monitoring, and integrated battery backup switching for CMOS RAM. It delivers up to 50mA from VOUT during main power operation, supports 140ms minimum reset pulse duration, and operates across –40°C to +85°C for industrial embedded systems requiring reliable power-fail warning and watchdog timing.
For engineers reviewing the LTC694IN8#PBF datasheet, LTC694IN8#PBF pinout, LTC694IN8#PBF application, or LTC694IN8#PBF equivalent, this device serves as a drop-in industrial-grade replacement for MAX690-family supervisory circuits with verified battery switchover, power-fail comparator, and watchdog timer functionality in PDIP-8 packaging.
Technical Context
The LTC694IN8#PBF integrates a bandgap voltage reference, precision comparator C1 (4.65V threshold, 40mV hysteresis), and charge-pumped NMOS power switch (5Ω typical RDS(on)) for VOUT regulation. Its internal watchdog timer uses either a fixed-frequency internal oscillator or external clock input via OSC IN/OSC SEL pins, delivering long (1.6s) or short (100ms) timeout periods.
Battery switchover is managed by comparator C2, which connects VOUT to VBATT when VCC falls 50mV below VBATT (with 20mV hysteresis) and switches back when VCC rises 70mV above VBATT. The PFI/PFO circuit employs a 1.3V internal reference to generate early power-fail warnings independent of VCC level.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Voltage Threshold | 4.65V typical; ensures µP reset activation before VCC drops below 4.75V (5% tolerance margin). |
| Minimum Reset Active Time | 140ms typical; guarantees stable µP initialization after power-up or brownout recovery. |
| VOUT Output Current | 50mA max; sufficient to power CMOS RAM and small peripherals without external boost. |
| Battery Switchover Threshold | VCC − VBATT = 50mV (power-down); prevents oscillation during marginal supply transitions. |
| Supply Current (Active) | 1.5mA max; enables low-power system monitoring without significant load on primary supply. |
| Standby Current (VBATT mode) | 1µA max; extends backup battery life for years in memory-retention applications. |
| Operating Temperature Range | –40°C to +85°C; qualified for automotive and industrial environments without derating. |
Pinout & Package
Package: 8-lead PDIP (N8), through-hole, JEDEC MS-001, 0.300" wide body, 0.100" lead pitch.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VCC) | Main 5V supply input | Must be bypassed with ≥0.1µF capacitor; powers all internal circuitry and VOUT switch. |
| 2 (VOUT) | Backed-up memory supply output | Delivers regulated 5V-equivalent to RAM; sourced from VCC (NMOS) or VBATT (PMOS) automatically. |
| 3 (PFI) | Power-fail input | Noninverting input to 1.3V-referenced comparator; triggers PFO when voltage falls below threshold. |
| 4 (GND) | Analog/digital ground reference | Common return for all internal blocks; requires low-impedance connection to system ground plane. |
| 5 (WDI) | Watchdog timer input | Three-level input (high/low/floating); resets timeout counter on each transition; floating disables watchdog. |
| 6 (VBATT) | Backup battery input | Accepts 2.0V–4.25V auxiliary source; supplies VOUT during main power loss via PMOS switch. |
| 7 (PFO) | Power-fail output | Open-drain logic output; goes low when PFI < 1.3V, enabling µP interrupt for controlled shutdown. |
| 8 (RESET) | Active-low microprocessor reset | Guaranteed logic low down to VCC = 1V; holds µP in reset until supply stabilizes post-brownout. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset at VCC = 1V | Ensures deterministic µP shutdown even during deep brownouts, preventing undefined state corruption. |
| Integrated battery switchover | Automatic NMOS/PMOS switching eliminates need for external diodes or OR-ing controllers in RAM backup paths. |
| Adjustable reset timing (via OSC SEL) | Enables fixed 200ms typical reset or user-defined timing using external capacitor on OSC IN pin. |
| Low-quiescent-current standby mode | 1µA max VBATT current preserves lithium or supercapacitor energy for multi-year data retention. |
| Power-fail comparator with 1.3V reference | Provides precise early-warning signal independent of VCC variation, supporting robust shutdown sequencing. |
Applications
| Industrial PLC Power Monitoring | Automotive Infotainment Memory Backup |
|---|---|
Use Scenario: Continuous monitoring of 5V rail in programmable logic controller during factory floor voltage sags. IC Role / Device Role / Timing Role: Supervisory IC asserting RESET to halt CPU execution and trigger nonvolatile save routines before brownout. Use Value: 140ms guaranteed reset pulse ensures full register dump completion even under 100ms grid interruptions. |
Use Scenario: Maintaining SRAM contents during engine start-up when vehicle battery dips below 9V. IC Role / Device Role / Timing Role: Battery switchover controller routing power from backup Li-ion cell to infotainment RAM during cranking. Use Value: 50mV switchover hysteresis prevents oscillation during noisy 12V transients, ensuring uninterrupted memory retention. |
| Medical Device Power-Fail Warning | Point-of-Sale Terminal Watchdog Protection |
Use Scenario: Detecting imminent AC power loss in portable diagnostic equipment to initiate safe shutdown and data archiving. IC Role / Device Role / Timing Role: PFI/PFO interface generating interrupt to µP 15ms before VCC crosses 4.75V reset threshold. Use Value: Configurable hysteresis via external resistor network enables noise-immune early warning in EMI-heavy clinical environments. |
Use Scenario: Preventing firmware lockup in retail payment terminals exposed to electromagnetic interference or software faults. IC Role / Device Role / Timing Role: Watchdog timer forcing hardware reset if WDI pin fails to toggle within 1.6s timeout window. Use Value: Internal oscillator eliminates need for external timing components while maintaining ±20% timeout accuracy over temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690EPA+ | 4.65V reset threshold, 200ms reset timeout, no integrated battery switchover; requires external diode for backup path. | Lacks VOUT/VBATT automatic switching; suitable only where backup power is externally managed. | Select when legacy MAX690 footprint compatibility is required and battery management is handled separately. |
| TPS3823MPW | 4.63V reset threshold, 200ms fixed timeout, 1.2µA quiescent current, but no PFI/PFO or watchdog functions. | Provides basic reset only; cannot replace LTC694IN8#PBF in systems requiring power-fail warning or watchdog supervision. | Choose only for simple reset-only applications where cost and ultra-low current outweigh feature requirements. |
Compared with MAX690EPA+ and TPS3823MPW, the LTC694IN8#PBF uniquely integrates battery switchover, power-fail comparator, and watchdog timer in a single 8-pin PDIP package-enabling complete µP supervision without additional discrete components or layout area.
Availability
LTC694IN8#PBF is available at Aetrix Electronics and suitable for industrial control systems, automotive electronics, medical devices, and point-of-sale terminals requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC694IN8#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for the LTC® family of precision analog ICs.
The LTC694IN8#PBF belongs to the LTC690/LTC694 supervisory family, designed specifically for robust power monitoring, battery-backed memory protection, and fail-safe microprocessor reset in harsh industrial and automotive environments.
FAQ
What is the guaranteed minimum reset pulse width for LTC694IN8#PBF?
The LTC694IN8#PBF guarantees a minimum reset active time of 140ms at VCC = 5V and TA = 25°C, with typical value of 200ms. This duration remains valid across the full –40°C to +85°C operating range and ensures reliable microprocessor initialization after power-up or brownout recovery. The LTC694IN8#PBF achieves this using its internal oscillator when OSC SEL is high or floating.
Does LTC694IN8#PBF support battery backup for CMOS RAM without external components?
Yes, the LTC694IN8#PBF provides fully integrated battery backup switching: its internal NMOS switch (5Ω typical) delivers up to 50mA from VCC to VOUT during normal operation, and its PMOS switch automatically routes VBATT to VOUT when VCC falls below VBATT minus 50mV. No external diodes, MOSFETs, or control logic are required for basic RAM backup functionality in the LTC694IN8#PBF.
Can LTC694IN8#PBF generate an early power-fail warning before reset assertion?
Yes, the LTC694IN8#PBF includes a dedicated PFI/PFO circuit with a 1.3V internal reference. By connecting PFI to a voltage divider from the main supply, the LTC694IN8#PBF asserts PFO low several milliseconds before VCC crosses the 4.65V reset threshold-providing critical time for µP-initiated data save and graceful shutdown prior to forced reset.
What is the maximum allowable voltage on the VBATT pin of LTC694IN8#PBF?
The absolute maximum rating for the VBATT pin of LTC694IN8#PBF is 6.0V, but the recommended operating range is 2.0V to 4.25V per Electrical Characteristics. Exceeding 4.25V may compromise long-term reliability of the internal PMOS battery switch and is not characterized for performance or lifetime. Always refer to the LTC694IN8#PBF datasheet for validated operating conditions.
How does the watchdog timer in LTC694IN8#PBF respond to WDI pin states?
The LTC694IN8#PBF watchdog timer resets its internal counter on every transition (rising or falling) of the WDI pin. If WDI remains static (high or low) longer than the programmed timeout period (1.6s long or 100ms short), both RESET and WDO outputs go active low. Floating WDI disables the watchdog function entirely-ensuring the LTC694IN8#PBF remains fully functional even when watchdog supervision is not required.
LTC694IN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- Simple Reset/Power-On Reset
- Number of Voltages Monitored:
- 1
- Voltage - Threshold:
- 4.65V
- Output:
- Open Drain or Open Collector
- Reset:
- Active High/Active Low
- Reset Timeout:
- 140ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LTC694IN8#PBF FAQ
1.How can I place an order for LTC694IN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC694IN8#PBF 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 LTC694IN8#PBF reliable?
The price and inventory of LTC694IN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC694IN8#PBF is usually 5 days.
3.What payment methods are accepted for LTC694IN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC694IN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC694IN8#PBF?
LTC694IN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC694IN8#PBF 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 LTC694IN8#PBF?
For technical support, including LTC694IN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC694IN8#PBF requirements.
6.How does Aetrix verify that LTC694IN8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC694IN8#PBF 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 LTC694IN8#PBF meets industry standards.
7.What is the process for return or replacement of LTC694IN8#PBF?
All LTC694IN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC694IN8#PBF, 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 LTC694IN8#PBF part is unused and in its original packaging.
Return procedure for LTC694IN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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