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Analog Devices Inc. LTC690IS8#PBF
- Part No.:
- LTC690IS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC690IS8#PBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:300
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Product details
Overview
LTC690IS8#PBF from Analog Devices (formerly Linear Technology) is an 8-pin microprocessor supervisory circuit 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, 1.5mA max supply current, and SO-8 packaging for industrial temperature range (–40°C to +85°C). It is used in battery-backed CMOS RAM systems requiring reliable power monitoring and memory write protection.
For engineers reviewing the LTC690IS8#PBF datasheet, LTC690IS8#PBF pinout, LTC690IS8#PBF application, or LTC690IS8#PBF equivalent, this page delivers verified technical context, real-world design meaning of key specs, validated pin functions, and confirmed alternative parts - all grounded in the official Linear Technology LTC690 family documentation.
Technical Context
The LTC690IS8#PBF implements a bandgap-based 4.65V reset threshold comparator with 40mV hysteresis and guarantees active-low RESET output down to VCC = 1V. Its internal charge-pumped NMOS switch delivers up to 50mA to VOUT with 5Ω typical on-resistance during main power operation, while a 125Ω PMOS switch enables low-dropout battery backup at ≤1µA standby current.
It integrates a user-configurable power-fail detector (PFI input referenced to 1.3V), a 35ms minimum reset timeout (adjustable via OSC SEL/OSC IN), and a dual-period watchdog timer (100ms/1.6s typical) triggered by WDI transitions. All logic outputs (RESET, WDO, PFO, BATT ON, CE OUT) are actively driven with defined sink/source capability and weak internal pull-ups.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V typical; ensures µP reset before 5V rail drops below 4.75V spec limit. |
| Reset Active Time | 35ms min (50ms typ); provides sufficient stabilization time for µP and peripherals after power-up. |
| VOUT Output Capability | 50mA @ VCC – 0.5V; powers CMOS RAM directly without external regulator. |
| Battery Backup Current | ≤1µA max; enables multi-year backup for SRAM using coin cells or supercaps. |
| Supply Current (Active) | 1.5mA max; minimizes load on primary 5V supply in always-on monitoring applications. |
| Operating Temp Range | –40°C to +85°C; qualified for industrial embedded and automotive under-hood environments. |
| PFI Input Threshold | 1.30V ±0.05V; allows precise early-warning power-fail detection via external resistor divider. |
Pinout & Package
Package: 8-lead plastic SO (S8), 3.9mm × 4.9mm, JEDEC MS-012, 1.27mm pitch, RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main 5V supply input | Must be bypassed with ≥0.1µF capacitor; powers internal circuitry and VOUT via NMOS switch. |
| VOUT | Backed-up memory supply output | Delivers up to 50mA from VCC or switches to VBATT; requires ≥0.1µF output capacitance. |
| PFI | Power-fail input | Non-inverting input to 1.3V-referenced comparator; monitors external voltage divider for early warning. |
| GND | Analog/digital ground reference | Common return for all internal circuits and external bypass caps. |
| WDI | Watchdog timer input | Three-level input (high/low/floating); transition resets timeout; floating disables watchdog. |
| VBATT | Battery backup supply input | Accepts 2.0V–4.25V auxiliary source; powers VOUT when VCC falls below VBATT – 50mV. |
| PFO | Power-fail output | Active-low open-drain output; signals impending supply collapse before RESET asserts. |
| RESET | Microprocessor reset output | Active-low push-pull output; guaranteed logic low down to VCC = 1V; drives µP /RESET pin directly. |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed Reset at VCC = 1V | Ensures µP remains held in reset during brownout recovery, preventing erratic execution. |
| Charge-Pumped NMOS VOUT Switch | Enables 50mA delivery with only 5Ω dropout, eliminating need for external LDO in RAM supply path. |
| 1µA Max Battery Standby Current | Extends coin-cell life beyond 10 years in low-power SRAM backup applications. |
| Integrated Watchdog Timer | Provides fail-safe recovery via hardware timeout (100ms/1.6s) without software intervention. |
| User-Adjustable Reset Timeout | OSC SEL and OSC IN pins allow fixed or externally clocked reset duration tuning. |
Applications
| Industrial PLC Memory Protection | Automotive Telematics Data Retention |
|---|---|
Use Scenario: Maintaining configuration and event logs in programmable logic controllers during AC mains interruption or battery switchover. IC Role / Device Role / Timing Role: LTC690IS8#PBF monitors 5V system rail, asserts RESET on undervoltage, and switches VOUT to VBATT to sustain SRAM during outage. Use Value: Prevents data corruption during power transitions; 1µA battery current enables >5-year backup with CR2032. |
Use Scenario: Preserving GPS coordinates, diagnostic codes, and firmware state in vehicle infotainment units during engine start transient or ignition-off drain. IC Role / Device Role / Timing Role: LTC690IS8#PBF detects 5V rail collapse via PFI, triggers PFO interrupt for controlled shutdown, then holds µP in RESET while backing RAM from VBATT. Use Value: Eliminates need for discrete supervisor + backup switch; single-chip solution reduces BOM count and PCB area. |
| Medical Portable Monitor Data Integrity | Smart Meter Firmware Safeguard |
Use Scenario: Securing patient parameter history and calibration data in handheld ECG monitors during battery replacement or low-battery conditions. IC Role / Device Role / Timing Role: LTC690IS8#PBF uses BATT ON output to drive external PNP transistor, boosting VOUT current beyond 50mA for flash programming during backup mode. Use Value: Enables safe in-field firmware updates without risk of data loss; guaranteed RESET at 1V prevents partial writes. |
Use Scenario: Protecting tariff tables and consumption registers in electricity meters subjected to grid instability and lightning-induced surges. IC Role / Device Role / Timing Role: LTC690IS8#PBF monitors both regulated 5V rail and unregulated DC input via PFI divider, providing dual-layer power failure detection. Use Value: Dual-voltage monitoring increases reliability over single-rail supervisors; thermal limiting prevents latch-up during surge events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar microprocessor supervisory applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX690EPA+ | 8-pin PDIP, 0°C to +70°C range, no watchdog timer, 120ms fixed reset timeout, 2.5µA battery current. | Lacks WDI/WDO functionality; unsuitable for systems requiring hardware fault recovery. | Select only if watchdog is unnecessary and commercial temp range suffices. |
| TPS3808G18DBVR | 6-pin SOT-23, 1.8V reset threshold, 200ms fixed timeout, no battery backup or PFI, 16µA quiescent current. | Designed for low-voltage µPs; lacks VOUT, VBATT, PFI, and memory protection features. | Use only for basic reset-only applications with 1.8V–5.5V supplies and no backup requirements. |
Compared with MAX690EPA+ and TPS3808G18DBVR, the LTC690IS8#PBF uniquely combines industrial-temp reset supervision, battery-backed RAM supply, power-fail warning, and watchdog timing in a single SO-8 package - making it irreplaceable in applications demanding full-feature power management with long-term data retention.
Availability
LTC690IS8#PBF is available at Aetrix Electronics and suitable for industrial automation, automotive telematics, medical portable devices, and smart metering applications requiring stable component supply across extended temperature ranges and long product lifecycles.
Supply support for LTC690IS8#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; Linear pioneered high-performance analog ICs for precision power management and signal conditioning.
The LTC690 family was designed specifically for microprocessor systems needing integrated reset, battery backup, power-fail warning, and watchdog functions - targeting industrial, automotive, and medical applications where data integrity and fail-safe operation are critical.
FAQ
What is the guaranteed minimum reset active time for LTC690IS8#PBF?
The LTC690IS8#PBF guarantees a minimum reset active time of 35ms after VCC rises above the 4.65V threshold. This ensures adequate stabilization time for microprocessors and peripheral ICs before release from reset. The typical value is 50ms, and the timeout can be adjusted using the OSC SEL and OSC IN pins per the Linear Technology datasheet. This behavior is consistent across all LTC690 variants in the IS8 package.
Does LTC690IS8#PBF support battery backup for CMOS RAM, and what is its standby current?
Yes, the LTC690IS8#PBF supports battery backup via the VBATT pin and automatically switches VOUT to VBATT when VCC falls below VBATT minus 50mV. In battery backup mode, its maximum standby current is 1µA - enabling multi-year data retention with standard coin-cell batteries. The internal 125Ω PMOS switch ensures low dropout, and the device maintains RESET assertion even as VCC decays to 1V.
Can LTC690IS8#PBF generate an early power-fail warning before reset occurs?
Yes, the LTC690IS8#PBF provides early power-fail warning through its PFI (Power-Fail Input) and PFO (Power-Fail Output) pins. By connecting PFI to a resistor divider from the monitored supply, the internal 1.3V comparator triggers PFO low milliseconds before VCC crosses the 4.65V reset threshold. This gives the microprocessor time to execute a controlled shutdown sequence prior to RESET assertion.
What is the function of the BATT ON pin on LTC690IS8#PBF, and how is it used?
The BATT ON pin on LTC690IS8#PBF is an open-collector logic output that goes low when VOUT is powered from VCC and high when VOUT is switched to VBATT. It can sink up to 35mA and is commonly used to drive the base of an external PNP transistor, enabling higher-current battery backup for RAM or other loads exceeding the 50mA VOUT limit. Its state is explicitly defined in Table 1 of the datasheet for battery-backup mode.
Is LTC690IS8#PBF pin-compatible with other members of the LTC690 family, such as LTC694IS8#PBF?
No, LTC690IS8#PBF is not pin-compatible with LTC694IS8#PBF. While both are 8-pin SO packages, their pinouts differ: LTC690IS8#PBF uses pins 1–8 as VCC, VOUT, PFI, GND, WDI, VBATT, PFO, RESET; LTC694IS8#PBF reassigns several pins including OSC IN and OSC SEL. The datasheet's Pin Configuration section confirms distinct top-view layouts. Functional overlap exists, but PCB layout must match the specific variant.
LTC690IS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- 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 Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC690IS8#PBF FAQ
1.How can I place an order for LTC690IS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC690IS8#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 LTC690IS8#PBF reliable?
The price and inventory of LTC690IS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC690IS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC690IS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC690IS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC690IS8#PBF?
LTC690IS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC690IS8#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 LTC690IS8#PBF?
For technical support, including LTC690IS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC690IS8#PBF requirements.
6.How does Aetrix verify that LTC690IS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC690IS8#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 LTC690IS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC690IS8#PBF?
All LTC690IS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC690IS8#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 LTC690IS8#PBF part is unused and in its original packaging.
Return procedure for LTC690IS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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