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Analog Devices Inc. LTC1921CS8#PBF
- Part No.:
- LTC1921CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- Power Supply Controllers, Monitors
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1921CS8#PBF.pdf
- Description:
- IC DUAL PWR SUPPLY MONITOR 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,589
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Product details
Overview
LTC1921CS8#PBF from Analog Devices (acquired Linear Technology) is a dual –48V telecom supply and fuse monitor IC with integrated window comparators, precision bandgap reference, and three open-drain output switches. It independently monitors two –48V supplies for undervoltage (–37.5V to –39.5V), overvoltage (–68.5V to –71.5V), and fuse integrity, driving optoisolators per backplane standards. Designed for telecom switch cards and high-reliability DC distribution systems.
For engineers reviewing the LTC1921CS8#PBF datasheet, LTC1921CS8#PBF pinout, LTC1921CS8#PBF application, or LTC1921CS8#PBF equivalent, key selection criteria include guaranteed –40°C to 85°C operation, ±1V undervoltage fault tolerance, 1.6V overvoltage hysteresis, fuse detection threshold of 0.9–4.5V differential, and MSOP-8 package compatibility with SOIC-8 footprints.
Technical Context
The LTC1921CS8#PBF implements dual independent supply monitoring using precision window comparators with internal level-shifting circuitry, enabling direct connection to –48V rails without external biasing. Each supply input (VA, VB) feeds dedicated undervoltage/overvoltage comparators with fixed thresholds and hysteresis, while FUSE A/FUSE B inputs perform differential voltage comparisons against their respective supply pins.
Its output architecture uses three open-drain NMOS switches (OUT A, OUT B, OUT F) that sink current to RTN when faults occur-enabling direct drive of MOC207 optoisolators without external transistors. The device operates from –10V to –80V, tolerates –100V DC faults and ±200V transients, and enters undervoltage lockout below 13V (dual supply) or 19V (single supply).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Range | –10V to –80V: Enables direct monitoring of telecom –48V rails with margin for ripple and sag. |
| Undervoltage Threshold | –37.5V to –39.5V (max): Detects supply collapse before critical system brownout. |
| Overvoltage Threshold | –68.5V to –71.5V (max): Triggers protection during rectifier or regulator failure. |
| Fuse Detection Window | 0.9V to 4.5V differential: Accurately identifies open fuses via voltage drop across intact vs blown elements. |
| Output Switch RDS(ON) | 25Ω typical at –35V: Ensures sufficient current sinking capability for standard optocoupler LEDs (≥10mA). |
| Operating Temperature | –40°C to 85°C: Validated for industrial telecom chassis environments with convection cooling. |
| Transient Tolerance | ±200V (10µs): Survives lightning-induced surges on telecom backplanes without clamping diodes. |
Pinout & Package
Package: 8-pin SOIC (narrow, 0.150-inch width), RoHS-compliant, lead-free (Pb-free) finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VA (Pin 1) | Supply A Input | Monitored –48V rail; powers internal circuitry and feeds undervoltage/overvoltage comparator for Supply A. |
| FUSE A (Pin 2) | Fuse A Sense | Compares voltage to VA to detect open-circuit condition; requires external pull-up to RTN for fault indication. |
| RTN (Pin 3) | Return Reference | Common return node; must be at equal or higher potential than all other pins; connects to –48V return plane. |
| OUT F (Pin 4) | Fuse Status Output | Open-drain NMOS output that sinks current when either FUSE A or FUSE B is open; drives optoisolator cathode. |
| OUT A (Pin 5) | Supply A Status Output | Open-drain NMOS output that sinks current when VA is outside valid window; wired between OUT F and OUT A in typical config. |
| OUT B (Pin 6) | Supply B Status Output | Open-drain NMOS output that sinks current when VB is outside valid window; wired between OUT A and RTN in typical config. |
| FUSE B (Pin 7) | Fuse B Sense | Compares voltage to VB to detect open-circuit condition; functions identically to FUSE A. |
| VB (Pin 8) | Supply B Input | Monitored –48V rail; powers internal circuitry and feeds undervoltage/overvoltage comparator for Supply B. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent supply monitoring | Enables concurrent validation of redundant –48V feeds without cross-talk or shared failure modes. |
| Integrated fuse detection | Eliminates need for external sense resistors and comparators by measuring differential voltage across each fuse. |
| No precision external components required | Reduces BOM count and layout sensitivity-only three noncritical 47kΩ resistors and optoisolators needed. |
| Transient-hardened inputs | Withstands ±200V transients, meeting Telcordia GR-1089-CORE surge immunity requirements for central office equipment. |
| Undervoltage lockout (UVLO) | Prevents erratic behavior during brownout by forcing all outputs low when supply drops below 13V (dual) or 19V (single). |
Applications
| Telecom Backplane Monitoring | Networking Switch Card Power Supervision |
|---|---|
Use Scenario: Real-time status reporting of dual –48V power feeds in carrier-grade Ethernet switches. IC Role / Device Role / Timing Role: Dual supply/fuse supervisor generating opto-isolated fault signals for system management controllers. Use Value: Enables hot-swap-aware power sequencing and automatic failover by detecting undervoltage recovery at –42.5V with 1.6V hysteresis. | Use Scenario: Fuse integrity verification in modular line cards with distributed power architecture. IC Role / Device Role / Timing Role: High-voltage differential comparator detecting open fuses via 0.9–4.5V window on FUSE A/B pins. Use Value: Reduces field failure rate by catching degraded fuses before catastrophic short-circuit events, leveraging ±200V transient tolerance. |
| High-Voltage DC Distribution Panel | Industrial Telecom Power Shelf |
Use Scenario: Centralized monitoring of multiple –48V outputs feeding remote radio units (RRUs) in 5G base stations. IC Role / Device Role / Timing Role: Fault-signaling interface converting analog supply deviations into digital logic-level outputs for FPGA supervision. Use Value: Achieves <10mW typical power dissipation while operating from –10V to –80V, minimizing thermal load in densely packed shelves. | Use Scenario: Redundant power shelf with dual –48V inputs, requiring coordinated fuse and supply health reporting. IC Role / Device Role / Timing Role: Independent dual-channel monitor with OR'ed fuse output (OUT F) and cascaded supply outputs (OUT A → OUT B). Use Value: Supports compact design with 8-pin SOIC footprint and eliminates need for external voltage references or trimming resistors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual –48V supply and fuse monitoring applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1921IMS8#PBF | Same functionality but specified for –40°C to 85°C industrial temperature range with tighter initial accuracy. | Preferred for extended-temperature telecom chassis where ambient exceeds 70°C. | Select when guaranteed performance across full –40°C to 85°C is required; shares identical pinout and footprint. |
| LTC4252CMS8#PBF | Hot-swap controller with active current limiting, PWRGD output, and floating supply capability-not a direct functional replacement. | Used for inrush control and fault current limiting during board insertion, not passive monitoring. | Choose only if active hot-swap control is needed; requires redesign due to different control architecture and pin functions. |
Compared with LTC1921CS8#PBF, the LTC1921IMS8#PBF offers identical monitoring features with enhanced temperature specification, while the LTC4252CMS8#PBF serves a fundamentally different purpose-active current regulation versus passive fault detection-making it unsuitable as a drop-in substitute.
Availability
LTC1921CS8#PBF is available at Aetrix Electronics and suitable for telecom backplane monitoring, networking switch card supervision, and high-voltage DC distribution panels requiring stable component supply and long-term lifecycle support.
Supply support for LTC1921CS8#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 portfolio of high-performance analog and mixed-signal ICs for precision power, signal conditioning, and interface applications.
The LTC1921CS8#PBF belongs to Linear's legacy telecom power supervision product line, engineered specifically for robust –48V infrastructure monitoring in carrier-class equipment with stringent reliability and surge immunity requirements.
FAQ
What is the operating voltage range of the LTC1921CS8#PBF?
The LTC1921CS8#PBF operates from –10V to –80V referenced to RTN, enabling direct connection to –48V telecom supplies with headroom for ripple, sag, and transient excursions. Its absolute maximum rating withstands –100V DC faults and ±200V transients for less than 10µs, making it suitable for harsh central office environments where the LTC1921CS8#PBF is deployed.
How does the LTC1921CS8#PBF detect fuse failures?
The LTC1921CS8#PBF detects fuse failures by comparing the voltage at FUSE A (Pin 2) to VA (Pin 1) and FUSE B (Pin 7) to VB (Pin 8). When a fuse opens, the differential voltage exceeds the 0.9V to 4.5V detection window, causing OUT F (Pin 4) to sink current and indicate fault. This method eliminates external sense resistors and is validated across –40°C to 85°C for the LTC1921CS8#PBF.
Can the LTC1921CS8#PBF monitor supplies other than –48V?
Yes-the LTC1921CS8#PBF monitors any negative supply between –10V and –80V. While its preset thresholds (–37.5V undervoltage, –68.5V overvoltage) target –48V telecom systems, the device functions correctly with –24V, –36V, or –60V rails. The LTC1921CS8#PBF's wide input range and fixed thresholds make it adaptable to non-standard voltages where those trip points remain relevant.
What is the purpose of the OUT A and OUT B pins in the LTC1921CS8#PBF?
OUT A (Pin 5) and OUT B (Pin 6) are open-drain NMOS outputs that sink current when their respective supplies (VA or VB) fall outside the valid window. In standard configurations, OUT A connects between OUT F and OUT B, and OUT B connects between OUT A and RTN-creating a cascaded fault-signaling chain. This allows discrete status indication for each supply using minimal external components in the LTC1921CS8#PBF implementation.
Does the LTC1921CS8#PBF require external precision components?
No-the LTC1921CS8#PBF requires no precision external components. Its internal bandgap reference, trimmed comparators, and level-shifting circuitry eliminate the need for external voltage references, trimming resistors, or matched resistor dividers. Only three noncritical 47kΩ resistors and optoisolators (e.g., MOC207) are needed, simplifying design and improving long-term stability for the LTC1921CS8#PBF.
LTC1921CS8#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
- Applications:
- Dual Power Supply Monitor
- Voltage - Input:
- -
- Voltage - Supply:
- 10V ~ 80V
- Current - Supply:
- 160 µA
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1921CS8#PBF FAQ
1.How can I place an order for LTC1921CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1921CS8#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 LTC1921CS8#PBF reliable?
The price and inventory of LTC1921CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1921CS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1921CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1921CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1921CS8#PBF?
LTC1921CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1921CS8#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 LTC1921CS8#PBF?
For technical support, including LTC1921CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1921CS8#PBF requirements.
6.How does Aetrix verify that LTC1921CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1921CS8#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 LTC1921CS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1921CS8#PBF?
All LTC1921CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1921CS8#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 LTC1921CS8#PBF part is unused and in its original packaging.
Return procedure for LTC1921CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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