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Analog Devices Inc. LTC690CS8#TRPBF
- Part No.:
- LTC690CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC690CS8#TRPBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:891
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Product details
Overview
LTC690CS8#TRPBF from Analog Devices (formerly Linear Technology) is an 8-pin microprocessor supervisory IC integrating power-on reset, battery backup switching, power-fail warning, and watchdog timer functions. It features a 4.65V precision voltage monitor, guaranteed RESET assertion down to VCC = 1V, 35ms minimum reset active time, and low 1.5mA max supply current. It is used in battery-backed CMOS RAM systems for embedded controllers requiring reliable power monitoring and memory write protection.
For engineers reviewing the LTC690CS8#TRPBF datasheet, LTC690CS8#TRPBF pinout, LTC690CS8#TRPBF application, or LTC690CS8#TRPBF equivalent, key selection criteria include guaranteed reset at 1V VCC, 4.65V threshold accuracy, battery switchover hysteresis (20mV), PFI comparator response time (2µs falling), and SO-8 package compatibility with industrial temperature range (0°C to 70°C).
Technical Context
The LTC690CS8#TRPBF implements a bandgap-based precision voltage reference and three independent comparators (C1 for reset, C2 for battery switchover, C3 for power-fail detection), plus a watchdog timer with internal oscillator or external clock input. Its NMOS charge-pump VOUT switch delivers up to 50mA with 5Ω typical on-resistance, while the PMOS battery-backup path provides <1µA standby current and 125Ω effective resistance.
It supports dual-mode operation: OSC SEL high enables fixed internal timing (35ms reset, 1.6s/100ms watchdog), while OSC SEL low allows external capacitor or clock control. The CE IN/CE OUT gating logic ensures unconditional RAM write-protection during brownout, with 20ns propagation delay and rail-to-rail output swing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Voltage Threshold | 4.65V typical; ensures reliable µP reset before 5V supply drops below 4.75V spec limit |
| Reset Active Time (min) | 35ms; holds µP in reset long enough for power stabilization and clock lock |
| VOUT Dropout (IOUT = 50mA) | VCC – 0.50V; enables stable 4.5V output from 5V rail under full load |
| Battery Switchover Hysteresis | 20mV; prevents oscillation when VCC ≈ VBATT during brownout transitions |
| PFI Comparator Response Time | 2µs (falling); enables fast early-warning interrupt before critical supply collapse |
| Supply Current (active) | 1.5mA max; minimizes primary power draw in always-on supervisory role |
| Standby Current (VBATT mode) | 1µA max; extends backup battery life for multi-year CMOS RAM retention |
Pinout & Package
Package: 8-Lead Plastic SO (S8), RoHS-compliant, JEDEC MS-012AC, 3.9mm × 4.9mm body, 1.27mm pitch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | 5V Supply Input | Main power rail; requires 0.1µF bypass capacitor for noise immunity and stability |
| VOUT | Backed-Up Memory Output | Switched output delivering power to RAM; sourced from VCC (NMOS) or VBATT (PMOS) |
| PFI | Power-Fail Input | Noninverting input to 1.3V-referenced comparator; senses supply decay via external divider |
| GND | Ground Reference | Common return for all analog and digital circuitry; must be low-impedance |
| WDI | Watchdog Input | Three-level input (high/low/floating); resets watchdog timer on each transition |
| VBATT | Battery Backup Input | Auxiliary power source; activates when VCC falls 50mV below VBATT |
| PFO | Power-Fail Output | Open-drain logic output; asserts low when PFI < 1.3V to trigger µP shutdown sequence |
| RESET | Microprocessor Reset Output | Active-low open-drain output; guaranteed low down to VCC = 1V for safe shutdown |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed RESET at VCC = 1V | Ensures deterministic µP shutdown even during deep brownout, preventing undefined state |
| Charge-Pumped NMOS VOUT Switch | Delivers 50mA with 5Ω RDS(on), eliminating substrate injection and unwanted battery charging |
| Integrated Watchdog Timer | Configurable 100ms/1.6s timeout using internal oscillator or external clock input |
| Fast PFI Comparator Response | 2µs falling edge detection enables timely power-fail interrupt before system crash |
| Thermal Limiting Protection | Shuts down VOUT switch at ~155°C with 10°C hysteresis to prevent latch-up or damage |
Applications
| Industrial Embedded Controller | Automotive Body Control Module |
|---|---|
Use Scenario: Microcontroller-based HVAC controller with nonvolatile RAM storing calibration data and runtime logs. IC Role / Device Role / Timing Role: Supervisory IC providing power-on reset, battery-backed RAM retention during ignition-off, and early power-fail warning before vehicle battery sag. Use Value: Prevents RAM corruption during 12V battery dips to 9V; guarantees µP reset at 1V VCC to avoid runaway code execution. |
Use Scenario: Door module with EEPROM and real-time clock, powered from vehicle battery with transient load spikes. IC Role / Device Role / Timing Role: Monitors 5V LDO output for brownout, switches RAM to backup battery, and triggers watchdog reset if firmware hangs during CAN message processing. Use Value: Enables >10-year data retention with <1µA standby current; 35ms reset pulse meets automotive ASAM MCAL timing requirements. |
| Portable Medical Instrument | Smart Energy Meter |
Use Scenario: Handheld glucose meter with lithium coin cell and flash memory storing patient history. IC Role / Device Role / Timing Role: Provides reset supervision during battery replacement, detects low-battery condition via PFI, and gates memory writes during voltage transients. Use Value: Eliminates spurious resets during battery swap using VBATT pull-down resistor; 4.65V threshold matches LiMnO₂ discharge curve. |
Use Scenario: DIN-rail energy meter with RTC and tamper-detection SRAM, operating from AC-DC converter with line sags. IC Role / Device Role / Timing Role: Generates power-fail interrupt 8ms before main supply collapse, enabling secure data save to backup RAM before RESET assertion. Use Value: 2µs PFI response time captures fast sags from motor loads; PFO hysteresis prevents chatter during marginal supply conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690ESA+ | 4.65V reset threshold, 200ms reset timeout, no integrated watchdog timer, 8-pin SO package | Lacks watchdog and battery switchover; requires external components for RAM write protection | Choose when only basic reset and power-fail warning are needed, and cost sensitivity outweighs feature integration |
| TPS3823DBVR | 4.63V reset threshold, 200ms reset timeout, no battery backup or PFI input, SOT-23-5 package | Smaller footprint but omits battery management, power-fail warning, and watchdog-requires discrete support circuitry | Choose for space-constrained designs where only reset supervision is required and auxiliary functions are handled elsewhere |
Compared with MAX690ESA+ and TPS3823DBVR, the LTC690CS8#TRPBF delivers full supervisory integration-including guaranteed 1V reset, battery switchover, PFI/PFO, and watchdog-in a single SO-8 package, reducing BOM count and PCB area while enabling robust data retention in battery-powered systems.
Availability
LTC690CS8#TRPBF is available at Aetrix Electronics and suitable for industrial embedded controllers, automotive body electronics, portable medical devices, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC690CS8#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) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC690 family was designed specifically for microprocessor-based systems needing integrated power monitoring, battery backup, and fault recovery-targeting applications where data integrity, low-power standby, and deterministic reset behavior are critical.
FAQ
What is the guaranteed minimum reset active time for LTC690CS8#TRPBF?
The LTC690CS8#TRPBF guarantees a minimum reset active time of 35ms after VCC rises above the 4.65V threshold. This duration ensures sufficient time for the microprocessor and its peripherals to stabilize before releasing reset. The typical value is 50ms, and it remains valid over the full 0°C to 70°C operating temperature range. The LTC690CS8#TRPBF does not support adjustable reset timing-this feature is exclusive to the 16-pin LTC691/LTC695 variants.
Can LTC690CS8#TRPBF operate with a 3.3V supply instead of 5V?
No, the LTC690CS8#TRPBF is specified only for 4.75V to 5.5V VCC operation. Its internal voltage reference, comparators, and reset threshold (4.65V) are calibrated for 5V systems. Applying 3.3V will prevent proper reset assertion and disable the VOUT switch. For 3.3V systems, consider the LTC691CSW#TRPBF or other members of the LTC69x family explicitly rated for lower supply rails.
How does LTC690CS8#TRPBF handle battery replacement without causing spurious resets?
The LTC690CS8#TRPBF can exhibit oscillatory behavior during battery swap due to VBATT pin stray capacitance charging via standby leakage. To prevent this, connect a 4.3MΩ resistor from VBATT to GND while replacing the battery. This holds VBATT below the switchover threshold (VCC – 50mV), keeping the device in normal mode. The LTC690CS8#TRPBF's 1µA max standby current ensures negligible drain on the new battery after replacement.
What is the maximum load current supported by VOUT in battery-backup mode?
In battery-backup mode (VCC < VBATT), the LTC690CS8#TRPBF delivers VOUT through a 125Ω PMOS switch, limiting practical load current to ≤250µA for minimal dropout. At 250µA, VOUT = VBATT – 0.1V. Higher currents cause excessive voltage drop and reduce backup runtime. For >250µA loads, use the LTC691 or LTC695 with their higher-current NMOS VOUT switch and CE OUT gating capability.
Does LTC690CS8#TRPBF include a watchdog timer, and how is it configured?
Yes, the LTC690CS8#TRPBF includes a watchdog timer with two timeout periods: 100ms (short) and 1.6s (long), selected via the OSC IN signal when OSC SEL is high. The timer resets on every WDI pin transition (rising or falling edge). If WDI remains static beyond the timeout, both RESET and WDO go active low. Floating WDI disables the watchdog. The LTC690CS8#TRPBF does not support external clock input-this requires OSC SEL = low and is unavailable in the 8-pin variant.
LTC690CS8#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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC690CS8#TRPBF FAQ
1.How can I place an order for LTC690CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC690CS8#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 LTC690CS8#TRPBF reliable?
The price and inventory of LTC690CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC690CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC690CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC690CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC690CS8#TRPBF?
LTC690CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC690CS8#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 LTC690CS8#TRPBF?
For technical support, including LTC690CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC690CS8#TRPBF requirements.
6.How does Aetrix verify that LTC690CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC690CS8#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 LTC690CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC690CS8#TRPBF?
All LTC690CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC690CS8#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 LTC690CS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC690CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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