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Analog Devices Inc. LTC690IN8#PBF
- Part No.:
- LTC690IN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LTC690IN8#PBF.pdf
- Description:
- IC SUPERVISOR 1 CHANNEL 8DIP
- Quantity:
- Payment:
- Shipping:
Inventory:1,056
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Product details
Overview
LTC690IN8#PBF from Analog Devices (formerly Linear Technology) is an 8-pin microprocessor supervisory IC integrating power-on reset, battery backup switchover, 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 1µA max standby current in battery-backup mode. It is used in battery-powered controllers and embedded systems requiring reliable µP reset and CMOS RAM write protection.
For engineers reviewing the LTC690IN8#PBF datasheet, LTC690IN8#PBF pinout, LTC690IN8#PBF application, or LTC690IN8#PBF equivalent, key selection criteria include guaranteed low-VCC reset behavior, integrated NMOS/PMOS battery switchover, PFI/PFO comparator thresholds, watchdog timeout configurability via OSC SEL, and compatibility with industrial temperature range (–40°C to +85°C).
Technical Context
The LTC690IN8#PBF implements a bandgap-based 4.65V reset threshold comparator (C1) with 40mV hysteresis and guarantees RESET remains logic low down to VCC = 1V. Its internal charge-pumped NMOS switch delivers up to 50mA to VOUT with 5Ω typical on-resistance during main supply operation, while a 125Ω PMOS switch enables low-dropout battery backup at ≤1µA quiescent current.
It integrates a dual-mode watchdog timer: internal oscillator provides 100ms/1.6s timeout periods (selected by OSC IN), and external clock input supports programmable timeout via OSC SEL = LOW. The PFI input compares against a 1.3V reference to generate early power-fail warning via PFO, with response time <8µs (rising) and <2µs (falling).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reset Threshold | 4.65V typical; ensures reliable µP reset when 5V rail drops below 4.75V (5% tolerance) |
| Reset Active Time | 35ms min / 50ms typ; holds µP in reset long enough for power & core stabilization |
| VOUT Dropout (NMOS) | 5Ω typical on-resistance; enables ≤0.25V drop at 50mA load for stable RAM supply |
| Battery Standby Current | 1µA max; minimizes drain on backup cell during extended offline operation |
| PFI Threshold | 1.30V ±0.05V; allows precise early-warning detection of falling 5V supply via external divider |
| Watchdog Timeout | 100ms / 1.6s selectable; provides flexible fault-detection window for software supervision |
| Operating Temp Range | –40°C to +85°C; qualified for industrial environments without derating |
Pinout & Package
Package: 8-lead PDIP (N8), 0.3-inch width, through-hole mounting, θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Main 5V supply input | Bypassed with 0.1µF capacitor; powers internal circuitry and feeds VOUT via NMOS switch |
| VOUT | Backed-up memory supply output | Switches between VCC (NMOS) and VBATT (PMOS); delivers up to 50mA with low dropout |
| PFI | Power-fail input | Non-inverting input to 1.3V comparator; triggers PFO low when sensed voltage falls below threshold |
| GND | Analog/digital ground reference | Common return for all internal circuits and external bypass caps |
| WDI | Watchdog input | Three-level input (high/low/floating); resets watchdog timer on each transition; floating disables timer |
| VBATT | Battery backup input | Source for VOUT during main supply loss; 2.0V–4.25V operating range; connects to Li-cell or supercap |
| PFO | Power-fail output | Open-drain logic output; asserts low to warn µP of impending supply collapse before RESET activates |
| RESET | Active-low microprocessor reset | Guaranteed low down to VCC = 1V; minimum 35ms pulse width ensures robust boot initialization |
Key Features
| Feature | Design Value |
|---|---|
| Guaranteed reset at VCC = 1V | Ensures µP remains held in known state even during deep brownout or slow power decay |
| Charge-pumped NMOS VOUT switch | Eliminates substrate injection current into VBATT - critical for safe lithium battery charging |
| Integrated PFI/PFO comparator | Enables early power-fail interrupt generation with <8µs response, allowing graceful shutdown |
| Configurable watchdog timeout | Supports both fixed (100ms/1.6s) and externally clocked timeout modes for flexible firmware supervision |
| Industrial temperature grade | Rated –40°C to +85°C with full electrical specs guaranteed - no derating required in harsh environments |
Applications
| Microprocessor Power Monitoring | Battery-Backed CMOS RAM Protection |
|---|---|
Use Scenario: Monitoring 5V system supply in an industrial PLC controller during cold start and brownout events. IC Role / Device Role / Timing Role: Supervisory IC providing power-on reset, brownout detection, and watchdog supervision. Use Value: Guarantees µP reset assertion down to VCC = 1V and holds reset for ≥35ms, preventing erratic boot behavior under marginal supply conditions. |
Use Scenario: Maintaining data integrity in nonvolatile SRAM during AC power loss in a smart meter. IC Role / Device Role / Timing Role: Dual-role supervisor: supplies backed-up VOUT and controls CE/WE lines via external gating (using RESET). Use Value: Switches VOUT to VBATT within 20µs and limits battery drain to ≤1µA, enabling >5-year backup life with standard coin cell. |
| Early Power-Fail Warning System | Automotive Body Control Module |
Use Scenario: Detecting unregulated 12V supply decay in a telecom shelf management unit prior to 5V regulator collapse. IC Role / Device Role / Timing Role: Precision comparator interface (PFI/PFO) generating interrupt signal for controlled shutdown sequence. Use Value: 1.3V reference and <2µs comparator response enable warning ≥8ms before RESET activation, allowing full EEPROM save cycle completion. |
Use Scenario: Reset and memory supervision in a vehicle infotainment head unit exposed to wide ambient temperatures. IC Role / Device Role / Timing Role: Industrial-grade (–40°C to +85°C) supervisory IC managing µP reset, battery switchover, and watchdog timing. Use Value: Qualified operation across full automotive ambient range with no spec degradation; eliminates need for external thermal compensation. |
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 watchdog timer, no PFI/PFO comparator | Lacks power-fail warning and configurable watchdog; requires external components for RAM write protection | Choose when only basic reset and battery backup are needed, and watchdog/PFI functionality is handled elsewhere |
| TPS3823MPW | 4.63V reset threshold, 200ms fixed reset delay, no battery switchover, no VOUT output, no PFI input | Supplies only reset signal; no RAM backup power or early-warning capability; requires external battery diode | Choose for cost-sensitive designs where battery backup and power-fail warning are not required |
Compared with MAX690EPA+ and TPS3823MPW, the LTC690IN8#PBF uniquely integrates reset, watchdog, PFI/PFO, and NMOS/PMOS battery switchover in one 8-pin package - eliminating 3–4 discrete components and enabling true single-chip µP supervision with industrial temp support.
Availability
LTC690IN8#PBF is available at Aetrix Electronics and suitable for industrial control systems, battery-powered instrumentation, automotive body electronics, and embedded computing platforms requiring stable component supply across extended temperature ranges.
Supply support for LTC690IN8#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) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.
The LTC690 family was designed specifically for robust microprocessor supervision in demanding industrial and automotive environments - integrating reset, battery backup, power-fail warning, and watchdog functions into compact packages.
FAQ
What is the guaranteed minimum reset active time for LTC690IN8#PBF?
The LTC690IN8#PBF guarantees a minimum reset active time of 35ms after VCC rises above the 4.65V threshold. This duration ensures sufficient stabilization time for microprocessors and associated circuitry during power-up. The typical reset active time is 50ms, and the device maintains this specification across its full industrial temperature range (–40°C to +85°C). The LTC690IN8#PBF does not support adjustable reset timing - that feature is exclusive to the 16-pin LTC691/LTC695 variants.
Does LTC690IN8#PBF support battery-backed RAM write protection?
Yes, the LTC690IN8#PBF supports battery-backed RAM write protection using its RESET output to drive external CE/WE logic, as shown in Figure 7 of the datasheet. While it lacks dedicated CE IN/CE OUT pins (available only on 16-pin LTC691/LTC695), the active-low RESET signal can be inverted and buffered to gate memory chip-enable lines. The LTC690IN8#PBF also provides VOUT switching to VBATT during main supply loss, ensuring continuous power to CMOS RAM with ≤1µA standby current.
How does the PFI/PFO function work in LTC690IN8#PBF?
The PFI pin on the LTC690IN8#PBF connects to an internal 1.3V comparator (C3). When the voltage at PFI falls below 1.3V, the open-drain PFO output pulls low - signaling impending power failure. This allows the microprocessor to initiate a controlled shutdown before RESET activates. The comparator has no built-in hysteresis, but external hysteresis can be added using feedback resistors between PFO and PFI. The PFO output is forced low when VCC drops below VBATT, disabling the comparator during battery backup mode.
What is the maximum load current supported by VOUT on LTC690IN8#PBF?
The VOUT pin on the LTC690IN8#PBF supports up to 50mA continuous load current when powered from VCC via its internal charge-pumped NMOS switch, with a typical on-resistance of 5Ω. At 50mA, the dropout voltage is typically ≤0.25V. In battery-backup mode (VCC < VBATT), VOUT is supplied through a 125Ω PMOS switch, limiting practical current to ~250µA. For higher backup currents, external PNP transistor drive via the BATT ON pin is recommended - though BATT ON is not present on the 8-pin LTC690IN8#PBF (only on 16-pin variants).
Can LTC690IN8#PBF operate with a 3.3V main supply?
No, the LTC690IN8#PBF is specified only for 5V nominal operation: VCC must be 4.75V to 5.50V per Absolute Maximum Ratings and Electrical Characteristics tables. Its 4.65V reset threshold and internal circuitry are optimized for 5V systems. Applying 3.3V to VCC will prevent proper reset assertion, disable internal regulators, and violate operating specifications. For 3.3V systems, consider purpose-built supervisors like the LTC2915 or MAX6369 series.
LTC690IN8#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 Low
- Reset Timeout:
- 35ms Minimum
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LTC690IN8#PBF FAQ
1.How can I place an order for LTC690IN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC690IN8#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 LTC690IN8#PBF reliable?
The price and inventory of LTC690IN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC690IN8#PBF is usually 5 days.
3.What payment methods are accepted for LTC690IN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC690IN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC690IN8#PBF?
LTC690IN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC690IN8#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 LTC690IN8#PBF?
For technical support, including LTC690IN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC690IN8#PBF requirements.
6.How does Aetrix verify that LTC690IN8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC690IN8#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 LTC690IN8#PBF meets industry standards.
7.What is the process for return or replacement of LTC690IN8#PBF?
All LTC690IN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC690IN8#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 LTC690IN8#PBF part is unused and in its original packaging.
Return procedure for LTC690IN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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