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Analog Devices Inc. LT1249IS8#TRPBF
- Part No.:
- LT1249IS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- PFC (Power Factor Correction)
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1249IS8#TRPBF.pdf
- Description:
- IC PFC CTR AV CURR 100KHZ 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,841
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Product details
Overview
LT1249IS8#TRPBF from Analog Devices (formerly Linear Technology) is an active power factor correction (PFC) controller IC designed for universal offline AC/DC power supplies operating up to 1500W. It implements fixed-frequency (100kHz) current-mode PFC using line current averaging, delivers 1.5A peak gate drive, features 7.5V reference output, and achieves high power factor across wide load ranges without slope compensation.
For engineers reviewing the LT1249IS8#TRPBF datasheet, LT1249IS8#TRPBF pinout, LT1249IS8#TRPBF application, or LT1249IS8#TRPBF equivalent, key selection considerations include its 8-pin SOIC package, -40°C to +125°C industrial temperature rating, integrated 1.5A gate driver, instantaneous overvoltage protection, and synchronization capability for noise-sensitive multi-phase systems.
Technical Context
The LT1249IS8#TRPBF employs a voltage-controlled current-mode architecture with a square-law multiplier to reduce AC gain at light loads-maintaining low line current distortion and system stability. Its current amplifier uses transconductance (typ. 320 µmho) with internal clamping and 1.1V maximum RMOUT voltage limit for precise line current regulation.
It integrates a 100kHz oscillator, undervoltage lockout (16.5V turn-on / 10.5V turn-off), fast 1.5A totem-pole GTDR output, and dedicated CAOUT/MOUT pins for current loop control. Protection includes peak current limiting, instantaneous overvoltage shutdown via VAOUT sinking (44µA threshold), and line switching noise rejection via IAC input filtering.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 100 kHz fixed internal oscillator - enables compact magnetics and predictable EMI profile without external timing components. |
| Gate Driver Peak Current | 1.5 A - directly drives high-Ciss MOSFETs (e.g., IRF840) without external buffer, reducing layout complexity and propagation delay. |
| Reference Voltage | 7.5 V ±1.2% over temperature - stable precision reference for voltage error amplifier and system feedback scaling. |
| VCC UVLO Threshold | 16.5 V (turn-on) / 10.5 V (turn-off) - ensures reliable startup and graceful shutdown during brownout conditions. |
| Start-Up Supply Current | 250 µA max - enables trickle-start from high-impedance sources (e.g., 90kΩ resistor from rectified line). |
| Current Amplifier gm | 320 µmho typ - provides sufficient transconductance for tight line current tracking while avoiding subharmonic oscillation at 100kHz. |
| Synchronization Range | 127–160 kHz - allows external clock alignment in multi-converter systems to suppress beat frequencies and simplify EMI filtering. |
Pinout & Package
LT1249IS8#TRPBF is housed in an 8-lead plastic SOIC (S8) package, rated for industrial temperature operation (–40°C to +125°C) with θJA = 120°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pin 1) | Power and signal reference ground | Common return path for all internal circuits; must be low-inductance connection to minimize noise coupling into sensitive analog blocks. |
| CAOUT (Pin 2) | Current amplifier output | Drives PWM modulator duty cycle; low-state forces zero duty cycle; clamped at 8V to protect downstream circuitry. |
| MOUT (Pin 3) | Multiplier current output | Sinks current through RMOUT (4kΩ) to generate current-loop reference; voltage limited to –1.1V to prevent instability under surge. |
| IAC (Pin 4) | AC line voltage sensing input | High-impedance current input biased at 2V; series 32kΩ resistor enables simple RC filtering of switching noise from rectified line. |
| VAOUT (Pin 5) | Voltage error amplifier output | Clamped at 12V; controls multiplier gain; drops below 1.5V to disable multiplier output current during fault or no-load. |
| VSENSE (Pin 6) | Voltage feedback input | Inverting input of error amplifier; referenced to 7.5V internal VREF; bias current ≤ ±250 nA minimizes divider error. |
| VCC (Pin 7) | Supply voltage input | Operates from 11.5V to 25V; requires local 0.1µF ceramic + ≥56µF low-ESR electrolytic bypass for gate driver current spikes. |
| GTDR (Pin 8) | Gate driver output | 1.5A totem-pole output clamped at 15V; rise/fall time <25 ns with 1nF load; requires ≥5Ω series gate resistor to suppress overshoot. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 100kHz PWM frequency | Eliminates need for external timing components and slope compensation, simplifying design and improving consistency across production units. |
| Line current averaging architecture | Reduces harmonic distortion vs. peak-current-mode controllers, enabling smaller input chokes and compliance with IEC 61000-3-2 Class D limits. |
| Integrated 1.5A gate driver | Directly interfaces with standard 600V MOSFETs (e.g., IRF840), removing external driver ICs and associated layout parasitics. |
| Instantaneous overvoltage protection | Detects output overvoltage within one switching cycle via VAOUT sink current threshold (44µA), preventing capacitor over-stress and component failure. |
| Synchronization input (CAOUT) | Accepts external sync pulses (127–160kHz) to align switching edges across multiple converters, reducing beat frequencies and easing EMI filter design. |
| Low start-up current (250µA) | Enables reliable startup from high-value resistive dropper networks, eliminating need for auxiliary winding or dedicated startup ICs. |
Applications
| Industrial Motor Drives | Server Power Supplies |
|---|---|
Use Scenario: 3kW three-phase rectifier front-end with active PFC stage feeding isolated DC-DC modules. IC Role / Device Role / Timing Role: Primary PFC controller regulating boost converter to maintain sinusoidal input current and unity power factor. Use Value: Enables compliance with EN 61000-3-4 harmonic standards and reduces RMS input current by >25% versus passive PFC solutions. |
Use Scenario: 1.5kW redundant AC/DC power supply in 1U server chassis with strict thermal and EMI constraints. IC Role / Device Role / Timing Role: Fixed-frequency average-current-mode PFC controller driving interleaved boost stages synchronized to system clock. Use Value: Achieves >0.99 PF at 20% load and supports 127–160kHz sync to eliminate inter-converter beat frequencies in multi-rail designs. |
| Medical Imaging Power Systems | LED Streetlight Drivers |
Use Scenario: High-reliability 800W X-ray generator power supply requiring stable DC bus under rapid load transients. IC Role / Device Role / Timing Role: Core PFC controller with instantaneous OV protection and robust noise immunity for critical diagnostic equipment. Use Value: Prevents catastrophic overvoltage events during sudden load removal via sub-µs response time, protecting expensive downstream inverters and detectors. |
Use Scenario: Outdoor 400W LED streetlight with universal AC input (90–264VAC) and IP67-rated enclosure demanding high efficiency and long life. IC Role / Device Role / Timing Role: PFC controller operating in continuous conduction mode to deliver regulated 400V DC bus to downstream buck-boost LED driver. Use Value: Delivers >96% efficiency at full load and maintains >0.95 PF down to 10% load, extending capacitor lifetime via reduced ripple current stress. |
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 (50–200kHz); adjustable overvoltage/current thresholds; higher pin count and BOM cost. | Used where design flexibility (e.g., variable frequency for EMI tuning) or extended feature set (e.g., soft-start, enable pin) is required. | Select LT1248CN8 only if frequency programmability or additional protection configurability justifies larger footprint and higher cost. |
| UCC2818DG4 | Texas Instruments part; 16-pin SOIC; average-current-mode; 67kHz fixed frequency; lower gate drive (1A); different multiplier architecture. | Common in cost-sensitive industrial PSUs where 67kHz operation suffices and TI ecosystem support is preferred. | Choose UCC2818DG4 when TI reference designs, availability, or compatibility with existing TI-based platforms outweigh need for 100kHz speed and 1.5A drive. |
Compared with LT1249IS8#TRPBF, LT1248CN8 offers greater configuration flexibility at the expense of size and cost, while UCC2818DG4 trades switching speed and drive strength for broader vendor support and lower unit price in volume production.
Availability
LT1249IS8#TRPBF is available at Aetrix Electronics and suitable for industrial motor drives, server power supplies, medical imaging systems, and outdoor LED lighting requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT1249IS8#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 acquired Linear Technology in 2017 and continues to manufacture and support its high-performance analog and power management portfolio.
The LT1249IS8#TRPBF belongs to Linear's legacy power factor controller family, engineered specifically for universal-input, high-power offline AC/DC conversion with minimal external components and robust noise immunity.
FAQ
What is the operating temperature range for the LT1249IS8#TRPBF?
The LT1249IS8#TRPBF is specified for industrial operation from –40°C to +125°C junction temperature. Its S8 package has a thermal resistance of 120°C/W (junction-to-ambient), and the device includes internal thermal protection that disables switching if safe operating limits are exceeded. This makes LT1249IS8#TRPBF suitable for enclosed, high-ambient environments like server PSUs and industrial motor drives.
Does the LT1249IS8#TRPBF require slope compensation in current-mode operation?
No, the LT1249IS8#TRPBF does not require external slope compensation. Its fixed-frequency, line current averaging architecture inherently avoids subharmonic oscillation even at duty cycles above 50%, unlike peak-current-mode controllers. This eliminates the need for ramp injection circuitry and simplifies PCB layout-directly contributing to the "very few external parts" claim in the LT1249IS8#TRPBF datasheet.
How does the LT1249IS8#TRPBF implement overvoltage protection?
The LT1249IS8#TRPBF implements instantaneous overvoltage protection by monitoring VAOUT: when output overvoltage causes excessive current through the feedback divider, the voltage error amplifier sinks 44µA at its output, causing VAOUT to collapse and disabling the multiplier. This shuts off the boost switch within one switching cycle. The LT1249IS8#TRPBF also includes 22µA hysteresis to prevent chatter during recovery, ensuring clean re-enablement once VOUT drops by ~22V.
Can the LT1249IS8#TRPBF be synchronized to an external clock?
Yes, the LT1249IS8#TRPBF supports external synchronization via the CAOUT pin. Applying a pulse that pulls CAOUT below 0.35V (width <60ns) within the 127–160kHz range forces the internal oscillator to align. This capability is confirmed in the Electrical Characteristics table and Typical Performance section of the LT1249IS8#TRPBF datasheet, enabling coordinated switching in multi-converter systems to reduce beat frequencies and simplify EMI compliance.
What is the purpose of the MOUT pin on the LT1249IS8#TRPBF?
The MOUT pin on the LT1249IS8#TRPBF outputs the multiplier's current (IM), which flows through the external 4kΩ resistor RMOUT to generate the current-loop reference voltage. This voltage is applied to the non-inverting input of the current amplifier and is internally clamped to –1.1V maximum to prevent instability during line surges. The LT1249IS8#TRPBF datasheet specifies MOUT's role in establishing the line current command signal and details its voltage and current limits in both Absolute Maximum Ratings and Electrical Characteristics tables.
LT1249IS8#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:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1249IS8#TRPBF FAQ
1.How can I place an order for LT1249IS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1249IS8#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 LT1249IS8#TRPBF reliable?
The price and inventory of LT1249IS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1249IS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1249IS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1249IS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1249IS8#TRPBF?
LT1249IS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1249IS8#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 LT1249IS8#TRPBF?
For technical support, including LT1249IS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1249IS8#TRPBF requirements.
6.How does Aetrix verify that LT1249IS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1249IS8#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 LT1249IS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1249IS8#TRPBF?
All LT1249IS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1249IS8#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 LT1249IS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1249IS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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