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Analog Devices Inc. LTC1726IS8-2.5#PBF
- Part No.:
- LTC1726IS8-2.5#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Supervisors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1726IS8-2.5#PBF.pdf
- Description:
- IC SUPERVISOR 3 CHANNEL 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,060
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Product details
Overview
LTC1726IS8-2.5#PBF from Analog Devices (formerly Linear Technology) is a triple supply monitor and microprocessor supervisory IC designed for systems requiring simultaneous monitoring of 2.5V, 3.3V, and an adjustable voltage rail. It delivers ±1.5% threshold accuracy over temperature, 16µA typical supply current, and independently adjustable reset (tRT) and watchdog (tWT) timeout periods via external capacitors. It is used in notebook computers and intelligent instruments to ensure reliable power-on reset and software fault detection.
For engineers reviewing the LTC1726IS8-2.5#PBF datasheet, LTC1726IS8-2.5#PBF pinout, LTC1726IS8-2.5#PBF application, or LTC1726IS8-2.5#PBF equivalent, key selection criteria include its 2.5V/3.3V/ADJ input configuration, guaranteed RST assertion down to VCC3 ≥ 1V or VCC25 ≥ 1V, open-drain active-low reset output, and MSOP/SO-8 package compatibility with industrial temperature range (–40°C to +85°C).
Technical Context
The LTC1726IS8-2.5#PBF implements three independent voltage comparators with precision bandgap references to monitor VCC25 (2.5V), VCC3 (3.3V), and VCCA (adjustable, nominal 1V). Its reset logic asserts RST low whenever any monitored supply falls below its specified threshold - VRT25 = 2.337V (min), VRT3 = 3.023V (min), VRTA = 0.978V (min) - with glitch immunity ensuring no false triggering during supply transients.
Both reset timeout (via RT pin capacitor) and watchdog timeout (via WT pin capacitor) are fully programmable using the formulas tRT = 3.30 × CRT (CRT in pF, tRT in µs) and tWT = 21.8 × CWT (CWT in pF, tWT in µs). The device derives internal power from whichever of VCC3 or VCC25 is higher, guaranteeing correct RST state even when only one supply reaches 1V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC25 Threshold | 2.337V min / 2.375V typ - ensures reliable detection of 2.5V rail brownout before system instability |
| VCC3 Threshold | 3.023V min / 3.085V typ - matches standard 3.3V LVTTL/LVCMOS I/O supply tolerance |
| VCCA Threshold | 0.978V min / 1.000V typ - supports monitoring of 1.0V–1.2V core supplies or feedback dividers |
| Supply Current | 16µA typical - enables use in battery-powered portable equipment without significant drain |
| RST Output Type | Active-low open-drain - allows wired-OR reset bus and level-shifting up to 5V with external pull-up |
| Reset Timeout Range | Adjustable from ~5µs to >10s via 1pF–100nF CRT capacitor - accommodates diverse µP initialization times |
| Watchdog Timeout Range | Adjustable from ~33µs to >10s via 1pF–100nF CWT capacitor - aligns with software task execution windows |
Pinout & Package
Package: 8-Lead Plastic SO (Narrow, 0.150-inch width), RoHS-compliant lead-free finish, operating temperature range –40°C to +85°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC3 (Pin 1) | 3.3V supply sense input & auxiliary power source | Monitors 3.3V rail; powers internal circuitry when ≥1V and higher than VCC25; requires 0.1µF bypass |
| VCC25 (Pin 2) | 2.5V supply sense input & primary power source | Monitors 2.5V rail; powers internal circuitry when ≥1V and higher than VCC3; requires 0.1µF bypass |
| VCCA (Pin 3) | Adjustable threshold sense input (1V nominal) | High-impedance input for monitoring 1.0V–1.2V rails or DC/DC feedback nodes; can be tied to VCC3 or VCC25 if unused |
| GND (Pin 4) | Signal and power ground reference | Common return path for all comparators, timers, and RST output; must be low-impedance |
| WDI (Pin 5) | Watchdog timer clear input | Edge-triggered (rising/falling); resets watchdog timer on transition; must be toggled within tWT to prevent reset |
| RST (Pin 6) | Active-low open-drain reset output | Asserted low during power-up/brownout; deasserted after tRT expires; weak internal pull-up to VCC3 (~6µA) |
| WT (Pin 7) | Watchdog timeout timing node | Capacitor-to-ground sets tWT = 21.8 × CWT (µs); grounding disables watchdog function |
| RT (Pin 8) | Reset timeout timing node | Capacitor-to-ground sets tRT = 3.30 × CRT (µs); determines minimum reset pulse width after power stabilization |
Key Features
| Feature | Design Value |
|---|---|
| Triple independent supply monitoring | Simultaneously supervises 2.5V, 3.3V, and adjustable rail - eliminates need for multiple discrete supervisors |
| ±1.5% threshold accuracy over temperature | Ensures consistent trip points across –40°C to +85°C without calibration or trimming |
| Adjustable reset and watchdog timeouts | Two external capacitors enable precise tuning of tRT and tWT to match µP boot time and software loop duration |
| Guaranteed RST operation down to 1V supply | Enables robust reset assertion even during deep brownout - critical for fail-safe embedded control |
| Low 16µA supply current | Reduces standby power in portable and energy-sensitive applications without sacrificing supervision fidelity |
| Power-source arbitration logic | Automatically selects VCC3 or VCC25 as internal supply - guarantees RST validity regardless of power sequencing order |
Applications
| Desktop Computers | Notebook Computers |
|---|---|
Use Scenario: Monitoring ATX 3.3V, 2.5V, and CPU core voltage rails during cold start and thermal throttling. IC Role / Device Role / Timing Role: Triple-supply supervisor providing synchronized reset assertion and watchdog oversight of BIOS initialization. Use Value: Prevents boot failure due to undetected 2.5V rail collapse; adjustable tRT accommodates multi-phase VRM ramp-up timing. |
Use Scenario: Supervising main 3.3V, DDR2 2.5V, and adjustable 1.05V GPU core supply in space-constrained mobile platforms. IC Role / Device Role / Timing Role: Low-power supervisor ensuring clean reset during battery-to-AC transitions and sleep/wake cycles. Use Value: 16µA quiescent current extends battery life; ±1.5% thresholds maintain reliability across wide ambient temperature swings. |
| Intelligent Instruments | Network Servers |
Use Scenario: Validating isolated 3.3V digital, 2.5V ADC reference, and adjustable 1.2V FPGA I/O supplies in calibrated test equipment. IC Role / Device Role / Timing Role: Precision supervisor enabling deterministic reset behavior required for metrology-grade repeatability. Use Value: Tight threshold tolerance prevents spurious resets during sensitive measurement acquisition windows. |
Use Scenario: Monitoring redundant 3.3V management, 2.5V PCIe, and adjustable 1.1V CPU VDDQ rails in dual-socket server motherboards. IC Role / Device Role / Timing Role: Fault-tolerant supervisor coordinating reset propagation across complex power domains with manual reset support. Use Value: Open-drain RST allows wired-OR with other supervisors; adjustable tWT detects hung firmware threads in multi-core environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar triple-supply monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1326-2.5 | ±0.75% threshold accuracy (tighter), but fixed 2.363V/3.118V/1.0V thresholds; no adjustable tRT/tWT | Used where absolute threshold precision outweighs flexibility - e.g., calibration-critical instrumentation | Select LTC1326-2.5 when tighter tolerance is mandatory and external capacitor tuning is unnecessary |
| LTC1727-2.5 | Individual open-drain RST outputs per supply (RST25, RST3, RSTA); same ±1.5% accuracy and adjustable timeouts | Required when supply-specific fault isolation is needed - e.g., diagnosing which rail failed in field-repair scenarios | Choose LTC1727-2.5 when independent reset signaling per monitored rail improves system debuggability |
Compared with LTC1326-2.5, the LTC1726IS8-2.5#PBF trades threshold precision for programmable timing and broader voltage adaptability; compared with LTC1727-2.5, it reduces pin count and board area by consolidating reset into a single output - ideal for cost- and space-sensitive designs where aggregated fault reporting suffices.
Availability
LTC1726IS8-2.5#PBF is available at Aetrix Electronics and suitable for notebook computers, intelligent instruments, and network servers requiring stable component supply with industrial temperature range support and RoHS compliance.
Supply support for LTC1726IS8-2.5#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 its high-performance analog IC portfolio, emphasizing precision, reliability, and signal integrity for demanding industrial and computing applications.
The LTC1726 product line was designed specifically for multi-rail microprocessor supervision in desktop, portable, and embedded systems - delivering accurate, low-power, and configurable reset and watchdog functionality in compact SO-8 and MSOP packages.
FAQ
What is the exact supply voltage monitoring configuration supported by the LTC1726IS8-2.5#PBF?
The LTC1726IS8-2.5#PBF is factory-configured to monitor three specific rails: VCC25 (2.5V nominal), VCC3 (3.3V nominal), and VCCA (adjustable, typically 1.0V–1.2V). Its electrical characteristics specify VRT25 = 2.337V (min), VRT3 = 3.023V (min), and VRTA = 0.978V (min) thresholds. This configuration is fixed for the -2.5 variant and cannot be reconfigured to monitor 5V instead of 2.5V - that requires the LTC1726IS8-5#PBF.
How does the LTC1726IS8-2.5#PBF guarantee correct RST output state during low-voltage conditions?
The LTC1726IS8-2.5#PBF guarantees RST remains in the correct asserted (low) state for VCC3 ≥ 1V or VCC25 ≥ 1V, as confirmed in its Absolute Maximum Ratings and Electrical Characteristics tables. This is achieved through internal power-source arbitration - the device draws operating current from whichever of VCC3 or VCC25 is higher, ensuring functional reset logic even when only one supply reaches 1V. The RST output itself is open-drain with a weak internal pull-up to VCC3 (~6µA), allowing external pull-up to higher voltages if needed.
Can the watchdog timer in the LTC1726IS8-2.5#PBF be disabled, and how is this implemented?
Yes, the watchdog timer in the LTC1726IS8-2.5#PBF can be fully disabled. Per the Applications Information section, this is accomplished by connecting both the WDI (Pin 5) and WT (Pin 7) terminals to GND. When WT is grounded, the internal watchdog timing circuit is disabled; tying WDI to GND prevents any edge transitions that could inadvertently clear a running timer. With both pins grounded, the LTC1726IS8-2.5#PBF functions strictly as a triple-supply monitor with adjustable reset timeout only.
What capacitor values are required to achieve a 155ms reset timeout and 1s watchdog timeout with the LTC1726IS8-2.5#PBF?
To achieve tRT = 155ms (155,000µs), use CRT = tRT / 3.30 = 155,000 / 3.30 ≈ 47,000pF (47nF), as shown in Typical Application TA02. To achieve tWT = 1s (1,000,000µs), use CWT = tWT / 21.8 ≈ 1,000,000 / 21.8 ≈ 45,872pF (47nF), matching the same value. Both capacitors must be low-leakage types - ceramic capacitors are explicitly recommended in the datasheet for stability and minimal dielectric absorption effects.
Is the LTC1726IS8-2.5#PBF pin-compatible with other variants in the LTC1726 family, such as the MSOP-packaged versions?
Yes, the LTC1726IS8-2.5#PBF is pin-compatible with all other LTC1726 variants in the SO-8 (S8) package, including LTC1726ES8-2.5#PBF and LTC1726HS8-2.5#PBF. It is also functionally and pinout-compatible with the MSOP-8 (MS8) variants (e.g., LTC1726EMS8-2.5#PBF), as both packages share identical pin numbering, terminal functions, and electrical behavior - only the physical footprint and thermal characteristics (θJA = 150°C/W for SO-8 vs. 200°C/W for MSOP-8) differ.
LTC1726IS8-2.5#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:
- Multi-Voltage Supervisor
- Number of Voltages Monitored:
- 3
- Voltage - Threshold:
- 2.337V, 3.085V, Adj
- Output:
- Open Drain or Open Collector
- Reset:
- Active Low
- Reset Timeout:
- Adjustable/Selectable
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1726IS8-2.5#PBF FAQ
1.How can I place an order for LTC1726IS8-2.5#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1726IS8-2.5#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 LTC1726IS8-2.5#PBF reliable?
The price and inventory of LTC1726IS8-2.5#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1726IS8-2.5#PBF is usually 5 days.
3.What payment methods are accepted for LTC1726IS8-2.5#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1726IS8-2.5#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1726IS8-2.5#PBF?
LTC1726IS8-2.5#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1726IS8-2.5#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 LTC1726IS8-2.5#PBF?
For technical support, including LTC1726IS8-2.5#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1726IS8-2.5#PBF requirements.
6.How does Aetrix verify that LTC1726IS8-2.5#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1726IS8-2.5#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 LTC1726IS8-2.5#PBF meets industry standards.
7.What is the process for return or replacement of LTC1726IS8-2.5#PBF?
All LTC1726IS8-2.5#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1726IS8-2.5#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 LTC1726IS8-2.5#PBF part is unused and in its original packaging.
Return procedure for LTC1726IS8-2.5#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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