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Analog Devices Inc. LT1249CS8#TRPBF
- Part No.:
- LT1249CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- PFC (Power Factor Correction)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1249CS8#TRPBF.pdf
- Description:
- IC PFC CTR AV CURR 100KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,166
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Product details
Overview
LT1249CS8#TRPBF from Analog Devices (formerly Linear Technology) is an active power factor correction (PFC) controller IC designed for universal offline AC/DC power supplies. It implements fixed-frequency (100 kHz) current-mode PFC using line current averaging, delivers 1.5 A peak gate drive, features 7.5 V reference output, and achieves high power factor over wide load ranges without slope compensation. It is used in preregulators up to 1500 W.
For engineers reviewing the LT1249CS8#TRPBF datasheet, LT1249CS8#TRPBF pinout, LT1249CS8#TRPBF application, or LT1249CS8#TRPBF equivalent, key selection criteria include its 100 kHz switching frequency, 1.5 A gate driver capability, 9 mA quiescent supply current, instantaneous overvoltage protection, and synchronization support up to 160 kHz - all critical for stable, high-efficiency universal-input PFC stage design.
Technical Context
The LT1249CS8#TRPBF employs a voltage-controlled current-mode architecture with a multiplier containing a square gain function to reduce AC loop gain at light loads, maintaining low line current distortion and system stability. Its current amplifier uses transconductance (typ. 320 µmho) and is compensated to provide >300 gain at 120 Hz while limiting gain to <15 at 100 kHz to prevent subharmonic oscillation.
It integrates a 1.5 A fast totem-pole gate driver (clamped at 15 V), internal 100 kHz oscillator, undervoltage lockout (16 V turn-on / 10 V turn-off), and dedicated pins for line current sensing (IAC), voltage error amplification (VAOUT/VSENSE), multiplier output (MOUT), and current loop control (CAOUT). Protection includes peak current limiting and instantaneous overvoltage shutdown via VAOUT sinking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 100 kHz (internally fixed; enables compact magnetics and EMI filtering) |
| Gate Driver Peak Current | 1.5 A (directly drives high-Ciss MOSFETs without external buffer) |
| Reference Voltage | 7.5 V ±1.2% (stable, temperature-compensated reference for voltage loop) |
| Supply Current (Active) | 9 mA typ. (low quiescent draw supports high-efficiency operation) |
| VCC UVLO Thresholds | 16.5 V turn-on / 10.5 V turn-off (hysteresis prevents chatter during brownout) |
| Current Amplifier gm | 320 µmho typ. (sets loop gain and bandwidth for line current tracking) |
| Synchronization Range | 127–160 kHz (enables multi-phase interleaving or noise spreading) |
Pinout & Package
LT1249CS8#TRPBF is housed in an 8-lead plastic SOIC (S8) package, 0.150" wide, with standard JEDEC MS-012AC footprint and 1.27 mm pitch. Thermal resistance θJA = 120°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Power and signal reference ground | Common return for all analog and power circuits; must be low-impedance connection to minimize noise coupling |
| CAOUT (Pin 2) | Current amplifier output | Drives PWM modulator; low state forces zero duty cycle; clamped at 8 V |
| MOUT (Pin 3) | Multiplier current output | Sinks current through RMOUT (4 kΩ); develops current-loop reference; operates at negative potential |
| IAC (Pin 4) | AC line voltage sensing input | High-impedance current input (biased at 2 V); series 32 kΩ resistor enables simple RC noise filtering |
| VAOUT (Pin 5) | Voltage error amplifier output | Clamped at 12 V; controls multiplier gain; drops below 1.5 V to disable multiplier output |
| VSENSE (Pin 6) | Voltage feedback input | Inverting input of error amp; referenced to 7.5 V; senses output DC bus voltage |
| VCC (Pin 7) | Supply voltage input | Operates from 11.5–25 V; UVLO protects during startup/brownout; requires local 0.1 µF + bulk capacitor |
| GTDR (Pin 8) | Gate driver output | 1.5 A totem-pole output; clamped at 15 V; requires ≥5 Ω series gate resistor to suppress overshoot |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 100 kHz PWM frequency | Eliminates need for external timing components and slope compensation, simplifying layout and reducing BOM count |
| Line current averaging architecture | Reduces harmonic distortion vs. peak-current mode, enabling smaller boost inductor and higher PF across 10–100% load |
| Integrated 1.5 A gate driver | Directly drives MOSFET gates up to ~2 nF; eliminates discrete driver stage and associated propagation delay |
| Instantaneous overvoltage protection | Detects output overvoltage via VAOUT sink current (44 µA threshold); shuts down multiplier within one cycle |
| Synchronization capability (127–160 kHz) | Enables precise phase alignment in multiphase PFC systems or EMI reduction via frequency dithering |
| Low start-up supply current (250 µA max) | Allows trickle-start from high-value resistors; reduces auxiliary winding complexity in offline designs |
Applications
| Industrial Motor Drives | Server Power Supplies |
|---|---|
|
Use Scenario: 3 kW industrial AC/DC front-end with universal input (85–265 VAC) and 400 VDC bus. IC Role / Device Role / Timing Role: Primary PFC controller regulating boost converter to maintain >0.99 PF and low THD under dynamic load steps. Use Value: Enables compliance with IEC 61000-3-2 Class A limits; 100 kHz operation allows use of 750 µH boost inductor instead of >1 mH required at 65 kHz. |
Use Scenario: 1.5 kW redundant ATX-style server PSU with dual-phase interleaved PFC. IC Role / Device Role / Timing Role: One LT1249CS8#TRPBF per phase, synchronized externally to 140 kHz for ripple cancellation. Use Value: Synchronization reduces 100 kHz output ripple amplitude by >70%, easing downstream bulk capacitor sizing and thermal stress. |
| Medical Imaging Power Systems | LED Streetlight Drivers |
|
Use Scenario: 800 W X-ray generator power supply requiring ultra-low EMI and high reliability. IC Role / Device Role / Timing Role: Standalone PFC controller feeding isolated DC/DC stage; leverages low dead-zone IAC bias for clean zero-crossing detection. Use Value: Minimal line current dead zone ensures accurate zero-crossing sensing for downstream sync signals, critical for gated X-ray pulse timing. |
Use Scenario: 200 W outdoor LED driver operating from 90–305 VAC with >90% efficiency target. IC Role / Device Role / Timing Role: High-efficiency PFC preregulator delivering regulated 400 VDC bus to buck-boost LED current controller. Use Value: 9 mA quiescent current and 250 µA start-up current enable low no-load losses and reliable cold-start at –40°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar power factor controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1248CN8 | 16-pin PDIP; programmable switching frequency (50–250 kHz), adjustable overvoltage threshold, and user-configurable current limit | Used where design flexibility (e.g., EMI tuning, custom protection thresholds) outweighs board space and cost constraints | Choose LT1248CN8 when variable frequency or fine-grained protection adjustment is required; not pin-compatible with LT1249CS8#TRPBF |
| UCC28019ADR | Texas Instruments part; 65 kHz fixed frequency; lower gate drive (1 A); requires external slope compensation; different pinout and biasing | Targeted at cost-sensitive consumer power supplies (<500 W) with less stringent THD requirements | Choose UCC28019ADR for lower-cost, lower-power designs where 65 kHz operation and reduced gate drive are acceptable |
Compared with LT1248CN8, LT1249CS8#TRPBF offers simpler implementation and smaller footprint but sacrifices configurability; compared with UCC28019ADR, it provides higher gate drive, better line current fidelity at light loads, and superior noise immunity - making it preferred for industrial and medical-grade PFC stages.
Availability
LT1249CS8#TRPBF is available at Aetrix Electronics and suitable for industrial motor drives, server power supplies, medical imaging systems, and LED streetlight drivers requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1249CS8#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT1249 belongs to Linear's legacy high-voltage power factor controller family, engineered specifically for universal-input offline PFC stages demanding low THD, high efficiency, and robust protection in space-constrained designs.
FAQ
What is the maximum allowable voltage on the MOUT pin of the LT1249CS8#TRPBF?
The LT1249CS8#TRPBF specifies an absolute maximum MOUT pin voltage of –12 V under any condition, but normal operation must keep it ≤ –6 V to avoid gate driver malfunction. During surge events, voltages between –6 V and –12 V are tolerated only for <30 µs (three switching cycles); sustained violation risks FET destruction. External clamping (e.g., three-series Schottky diodes) is recommended for high-surge environments.
Does the LT1249CS8#TRPBF require slope compensation for stable operation?
No, the LT1249CS8#TRPBF does not require slope compensation. Its fixed-frequency current-mode architecture uses line current averaging and a square-law multiplier gain function to inherently stabilize the current loop across continuous and discontinuous conduction modes - eliminating slope compensation components and associated design complexity.
How does the LT1249CS8#TRPBF achieve synchronization, and what is the valid input signal range?
The LT1249CS8#TRPBF synchronizes via the CAOUT pin: an external transistor pulls CAOUT below 0.35 V to trigger synchronization. Valid sync frequency is 127–160 kHz; pulse width must be <60 ns. The internal oscillator is disabled during sync pulses, and recovery time depends on CAOUT slew rate - positive slewing must exceed 0.5 V/µs to ensure reliable resumption.
What is the purpose of the 32 kΩ resistor connected to the IAC pin on the LT1249CS8#TRPBF?
The 32 kΩ resistor in series with the IAC pin of the LT1249CS8#TRPBF establishes a high-impedance current-sensing node biased at 2 V, minimizing line current dead zone near zero-crossings. Combined with a small external capacitor to GND, it forms a simple, effective filter that rejects high-frequency switching noise - preventing instability caused by noise injection into the multiplier.
Can the LT1249CS8#TRPBF operate with a 230 VAC nominal input without hardware changes?
Yes, the LT1249CS8#TRPBF is explicitly designed for universal operation (85–265 VAC) without switches or configuration changes. Its internal circuitry - including UVLO thresholds, reference stability, and multiplier scaling - maintains high power factor and low THD across the full input range, as verified in typical application circuits with 230 VAC inputs.
LT1249CS8#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
- Mode:
- Average Current
- Frequency - Switching:
- 100kHz
- Current - Startup:
- 250 µA
- Voltage - Supply:
- 15.5V ~ 27V
- Operating Temperature:
- 0°C ~ 100°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1249CS8#TRPBF FAQ
1.How can I place an order for LT1249CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1249CS8#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 LT1249CS8#TRPBF reliable?
The price and inventory of LT1249CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1249CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1249CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1249CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1249CS8#TRPBF?
LT1249CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1249CS8#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 LT1249CS8#TRPBF?
For technical support, including LT1249CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1249CS8#TRPBF requirements.
6.How does Aetrix verify that LT1249CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1249CS8#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 LT1249CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1249CS8#TRPBF?
All LT1249CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1249CS8#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 LT1249CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1249CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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