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Analog Devices Inc. LTC690IS8#TRPBF
- Part No.:
- LTC690IS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC690IS8#TRPBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,164
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Product details
Overview
LTC690IS8#TRPBF from Analog Devices (formerly Linear Technology) is an industrial-grade microprocessor supervisory circuit in 8-lead SOIC package, integrating precision 4.65V power supply monitoring, battery backup switchover (VBATT to VOUT), power-fail warning (PFI/PFO), watchdog timer with 100ms/1.6s timeout options, and guaranteed RESET assertion down to VCC = 1V. It delivers up to 50mA from VOUT during main power operation and draws ≤1µA in battery-backup mode - used in battery-powered controllers and automotive ECUs requiring fail-safe reset behavior.
For engineers reviewing the LTC690IS8#TRPBF datasheet, LTC690IS8#TRPBF pinout, LTC690IS8#TRPBF application, or LTC690IS8#TRPBF equivalent, key selection criteria include guaranteed low-VCC reset assertion, integrated RAM write protection via CE gating (on LTC691/LTC695 variants), thermal limiting, and compatibility with 2.0V–4.25V backup batteries - all within a compact SO-8 footprint rated for –40°C to +85°C.
Technical Context
The LTC690IS8#TRPBF implements a bandgap-based 4.65V voltage monitor with 40mV hysteresis and guarantees active-low RESET output down to VCC = 1V, ensuring robust microprocessor hold-down during brownout. Its internal charge-pumped NMOS power switch delivers VOUT from VCC with 5Ω typical on-resistance and supports up to 50mA load current.
Battery switchover uses comparator C2 with 70mV turn-on and 50mV turn-off thresholds (20mV hysteresis) to seamlessly transfer VOUT from VCC to VBATT when primary supply fails. The watchdog timer operates from either internal oscillator (100ms/1.6s timeout) or external clock input (OSC IN), with WDI accepting three-level logic (high/low/floating) to enable/disable timing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V typical (4.5V–4.75V min/max); ensures reliable µP reset before 5V rail collapse. |
| Reset Active Time | 35ms minimum (50ms typical); holds µP in reset long enough for power stabilization. |
| VOUT Output Current | 50mA max from VCC; powers CMOS RAM or low-power peripherals without external regulator. |
| Battery Backup Current | ≤1µA standby; enables multi-year operation on coin-cell or supercapacitor backup sources. |
| Operating Temp Range | –40°C to +85°C; qualified for industrial and automotive under-hood environments. |
| Supply Current (Active) | 1.5mA maximum; minimizes primary supply loading in always-on monitoring applications. |
| VBATT Input Range | 2.0V to 4.25V; supports Li-MnO₂, Li-SOCl₂, and supercapacitor backup sources. |
Pinout & Package
S8 package: 8-lead plastic SOIC, 1.27mm pitch, JEDEC MS-012AC, body size 4.9mm × 3.9mm, thermal resistance θJA = 180°C/W (FR4, still air).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main 5V supply input | Bypass with 0.1µF capacitor; monitored for reset threshold violation and switchover control. |
| VOUT | Backed-up memory supply output | Delivers up to 50mA from VCC or VBATT; connects to CMOS RAM VCC pin for seamless backup. |
| PFI | Power-fail input | Non-inverting input to 1.3V-referenced comparator; triggers PFO low when voltage drops below 1.3V. |
| GND | Analog/digital ground reference | Common return for all internal circuits; must be low-impedance connection to system ground plane. |
| WDI | Watchdog timer input | Three-state input (high/low/floating); transition resets timeout; floating disables watchdog. |
| VBATT | Battery backup supply input | Connects to coin cell or capacitor; powers VOUT when VCC falls below VBATT −50mV. |
| PFO | Power-fail output | Open-drain output; goes low to warn µP of impending supply failure before RESET asserts. |
| RESET | Active-low microprocessor reset | Guaranteed logic-low output even at VCC = 1V; drives µP /RESET pin directly. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset at VCC = 1V | Ensures µP remains held in known state during deep brownout - critical for data integrity in battery-backed systems. |
| Integrated battery switchover | Automatic, hysteresis-controlled transfer between VCC and VBATT with <20µs response time and no external components required. |
| Low-quiescent-current backup mode | ≤1µA total supply current when VCC = 0V and VBATT = 2.8V - extends backup source lifetime by orders of magnitude. |
| Adjustable power-fail warning | PFI input accepts user-defined voltage divider to set early-warning threshold independent of reset threshold. |
| Thermal shutdown protection | Activates at ~155°C with ~10°C hysteresis; prevents damage during sustained overload or poor PCB heatsinking. |
Applications
| Industrial PLC Controller | Automotive Body Control Module |
|---|---|
Use Scenario: Continuous monitoring of 5V system rail in programmable logic controller with nonvolatile RAM and real-time clock. IC Role / Device Role / Timing Role: Supervisory IC providing reset assertion, battery-backed RAM power switchover, and early power-fail interrupt via PFO. Use Value: Prevents RAM corruption during line sags or battery replacement; enables graceful firmware shutdown before VCC drops below µP operational limit. |
Use Scenario: Power management in vehicle door module with EEPROM, CAN transceiver, and wake-on-LIN capability. IC Role / Device Role / Timing Role: Resets microcontroller on ignition cycle, monitors battery voltage decay, and signals impending loss of 5V supply to initiate safe state transition. Use Value: Guarantees deterministic reset at VCC = 1V - essential for meeting ISO 16750-2 transient immunity requirements. |
| Portable Medical Monitor | Smart Energy Meter |
Use Scenario: Battery-operated patient vital sign recorder with flash memory and real-time clock, requiring >5-year shelf life on primary cell. IC Role / Device Role / Timing Role: Provides ultra-low-current (≤1µA) backup power path and watchdog supervision to detect firmware lockup during sleep mode. Use Value: Eliminates need for external PMOS switch and discrete supervisor; reduces BOM count while meeting IEC 60601-1 leakage current limits. |
Use Scenario: Revenue-grade electricity meter with tamper detection, secure crypto engine, and backup SRAM storing billing data. IC Role / Device Role / Timing Role: Monitors AC-DC converter output, asserts RESET before brownout, and gates SRAM write-enable using CE OUT logic (LTC691/LTC695 variant function). Use Value: Ensures SRAM write-protection during power interruption - satisfies ANSI C12.1 and IEC 62053-21 data retention mandates. |
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 or watchdog; PDIP-8 only. | Lacks VOUT/VBATT switching and PFI/PFO functions - requires external diode-OR or PMOS circuit for backup power. | Select when only basic reset generation is needed and board space allows discrete backup implementation. |
| TPS3823DBVR | 4.63V reset threshold, 200ms timeout, no battery backup, no PFI/PFO, no watchdog; SOT-23-5 package. | Smaller footprint but omits all power-fail, backup, and watchdog features - suitable only for simple reset-only use cases. | Choose for cost-sensitive, space-constrained designs where advanced supervision is unnecessary. |
Compared with MAX690EPA+ and TPS3823DBVR, the LTC690IS8#TRPBF provides full integration of reset, battery switchover, power-fail warning, and watchdog in one SO-8 device - eliminating ≥4 external components and enabling single-chip supervision for mission-critical embedded systems.
Availability
LTC690IS8#TRPBF is available at Aetrix Electronics and suitable for industrial automation, automotive electronics, and portable medical devices requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for LTC690IS8#TRPBF 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 its high-reliability analog IC portfolio, emphasizing precision, robustness, and long-term manufacturability for industrial and automotive markets.
The LTC690 family was designed specifically for microprocessor system supervision - combining reset generation, battery backup, power-fail warning, and watchdog timing into a single IC to reduce system complexity and improve reliability in harsh environments.
FAQ
What is the guaranteed minimum VCC level at which LTC690IS8#TRPBF asserts RESET?
The LTC690IS8#TRPBF guarantees active-low RESET output even when VCC drops to 1V - a critical feature for holding microprocessors in a known state during deep brownout conditions. This specification is tested and guaranteed over the full –40°C to +85°C operating temperature range, unlike many competitors that specify reset only down to 2.5V or 3V. The internal comparator and output driver are optimized to maintain logic-level integrity at ultra-low supply voltages, making LTC690IS8#TRPBF suitable for applications with aggressive low-voltage tolerance requirements.
Does LTC690IS8#TRPBF support adjustable reset timeout duration?
No, the LTC690IS8#TRPBF has fixed reset active time of 35ms minimum (50ms typical) - this is inherent to the LTC690/LTC694 variant family. Adjustable reset timeout is only available on the LTC691 and LTC695 variants (16-pin packages) via external resistor/capacitor on OSC IN. The LTC690IS8#TRPBF uses its internal oscillator exclusively for timing, with no provision for external adjustment. Engineers requiring programmable reset duration must select LTC691ISW#TRPBF or LTC695ISW#TRPBF instead.
Can LTC690IS8#TRPBF drive CMOS RAM write-enable (WE) or chip-enable (CE) signals directly?
No, the LTC690IS8#TRPBF does not include dedicated CE IN/CE OUT pins - those are exclusive to the 16-pin LTC691 and LTC695 variants. For RAM write protection, LTC690IS8#TRPBF users must implement external gating using the RESET signal (e.g., NAND gate with address decoder) or rely on µP firmware to disable writes upon receiving RESET interrupt. This functional limitation is clearly indicated in the Product Selection Guide table, where LTC690 is marked "X" for RAM write protect but lacks CE IN/CE OUT pin entries in its 8-pin SOIC pinout.
What is the maximum allowable voltage on the VBATT pin of LTC690IS8#TRPBF?
The absolute maximum rating for VBATT is 6.0V, but the recommended operating range is 2.0V to 4.25V per Electrical Characteristics table. Exceeding 4.25V risks violating the battery switchover comparator's design margin and may cause premature or unstable switchover behavior. In battery-backup mode, VOUT tracks VBATT minus ~0.1V to 0.2V drop across the internal PMOS switch - so applying 4.25V to VBATT yields ~4.05V–4.15V at VOUT, sufficient for most 3.3V or 5V-tolerant CMOS RAMs. Always observe the 2.0V lower limit to ensure proper comparator biasing.
How does the watchdog timer in LTC690IS8#TRPBF respond to WDI pin states?
The WDI pin on LTC690IS8#TRPBF is a three-level input: driving it high or low for longer than the selected timeout period (100ms or 1.6s) forces both RESET and WDO low; leaving it floating disables the watchdog entirely. Each rising or falling edge on WDI resets the timeout counter - no edge-detection circuitry is required externally. The timeout period is selected by OSC SEL pin state: OSC SEL high selects internal oscillator with 100ms/1.6s options; OSC SEL low enables external clock input on OSC IN. This behavior is confirmed in Pin Functions and Applications Information sections of the datasheet.
LTC690IS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- 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 Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC690IS8#TRPBF FAQ
1.How can I place an order for LTC690IS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC690IS8#TRPBF 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 LTC690IS8#TRPBF reliable?
The price and inventory of LTC690IS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC690IS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC690IS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC690IS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC690IS8#TRPBF?
LTC690IS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC690IS8#TRPBF 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 LTC690IS8#TRPBF?
For technical support, including LTC690IS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC690IS8#TRPBF requirements.
6.How does Aetrix verify that LTC690IS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC690IS8#TRPBF 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 LTC690IS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC690IS8#TRPBF?
All LTC690IS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC690IS8#TRPBF, 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 LTC690IS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC690IS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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