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Analog Devices Inc. LT1248CS#TRPBF
- Part No.:
- LT1248CS#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- PFC (Power Factor Correction)
- Package:
- 16-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1248CS#TRPBF.pdf
- Description:
- IC PFC CTR AVERAGE 300KHZ 16SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:1,894
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Product details
Overview
LT1248CS#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency active power factor correction (PFC) controller IC designed for universal off-line preregulators up to 1500W. It implements current-mode line-current averaging with a square-law multiplier, delivers 1.5A peak gate drive, supports up to 300kHz switching, and features integrated overvoltage protection, soft-start, and synchronization capability - enabling high-efficiency AC/DC front-ends in industrial and telecom power supplies.
For engineers reviewing the LT1248CS#TRPBF datasheet, LT1248CS#TRPBF pinout, LT1248CS#TRPBF application, or LT1248CS#TRPBF equivalent, key selection criteria include its 7.5V reference accuracy (±0.18V), 100kHz typical oscillator frequency (RSET=15kΩ, CSET=1nF), 9mA active supply current, 250µA start-up current, and SO-16 narrow package thermal resistance of 120°C/W - all critical for stable high-power PFC loop design and thermal management.
Technical Context
The LT1248CS#TRPBF uses a voltage-controlled current-source architecture where the multiplier output IM = (IAC × IEA²)/(200µA)² defines the line-current reference, with IEA = (VAOUT − 2V)/25kΩ. Its dual error amplifiers - voltage amp (100dB DC gain, 3MHz GBW) and current amp (110dB DC gain, 3MHz GBW, 2V/µs slew) - maintain stability across load and line variations by enforcing gain >250 at 120Hz and <15 at switching frequency.
Protection is implemented via three independent circuits: OVP comparator (trip at 1.05×VREF = 7.875V, 100ns delay), PKLIM current-limit comparator (−15mV offset, 400ns propagation), and undervoltage lockout (16.5V turn-on, 10.5V turn-off). Synchronization is supported through EN/SYNC pin with 5V threshold and 200ns minimum pulse width.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Reference Voltage | 7.50V ±0.18V over temperature - provides stable bias for internal amplifiers and external resistor-divider feedback networks |
| Oscillator Frequency | 100kHz typical (RSET=15kΩ, CSET=1nF) - sets PFC switching frequency; adjustable from ~58kHz to 300kHz via RSET/CSET |
| Gate Driver Output | 1.5A peak sink/source, 25ns rise/fall (1nF load) - directly drives MOSFET gates without external buffers in ≤1500W designs |
| Supply Current (Active) | 12.0mA max at VCC=18V - enables low-loss auxiliary winding design and simplifies VCC regulation |
| Start-Up Current | 250µA typical - allows trickle-start using high-value resistor (e.g., 90kΩ) from rectified line to VCC |
| Voltage Amplifier Gain | 100dB DC gain, 3MHz unity-gain bandwidth - ensures tight output voltage regulation with minimal phase lag at 120Hz |
| Current Amplifier Gain | 110dB DC gain, 3MHz unity-gain bandwidth - maintains low line-current THD (<5%) under light-load and wide-line conditions |
Pinout & Package
LT1248CS#TRPBF is housed in a 16-lead narrow plastic SOIC (S package), 150-mil width, with θJA = 120°C/W. Pin 1 is bottom-left corner (GND), pin 16 is top-right (GTDR), and all pins are surface-mount compatible with standard reflow profiles.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1) | Power and signal reference ground | Common return for internal amplifiers, reference, and gate driver; must be low-impedance connection to PCB ground plane |
| PKLIM (2) | Peak current limit comparator input | Threshold referenced to GND; used with resistor divider from VREF to sense-resistor to set secondary overcurrent protection |
| CAOUT (3) | Current amplifier output | Drives PWM modulator; low state forces zero duty cycle; clamped at 8.5V/1.1V for safe MOSFET control |
| ISENSE (4) | Inverting input of current amplifier | Accepts voltage from current-sense resistor; ESD-clamped at −0.6V to prevent damage during fault conditions |
| MOUT (5) | Multiplier current output / CA non-inverting input | High-impedance current source feeding current loop; clamped at −0.6V/2V to limit transients |
| IAC (6) | AC line voltage sensing input | Biased at 2V to minimize dead zone; 32kΩ series resistor enables simple RC filtering of switching noise |
| VAOUT (7) | Voltage amplifier output | Clamped at 13.5V/2.0V; controls multiplier gain; drops below 2.5V to disable multiplier output |
| OVP (8) | Overvoltage comparator input | Trips at 1.05×VREF (≈7.875V); fast shutdown prevents output capacitor overvoltage during sudden load removal |
| VREF (9) | Internal 7.5V precision reference | Sources up to 5mA; powers internal circuitry and external resistive dividers; disabled when EN/SYNC or VCC is low |
| EN/SYNC (10) | Enable and synchronization input | Below 2.6V → shutdown (0.5mA supply); pulses <5V with >200ns width → synchronize oscillator to external clock |
| VSENSE (11) | Inverting input of voltage amplifier | Summing node for output voltage feedback; held at 7.5V by VREF; connects to resistor divider from VOUT |
| RSET (12) | Oscillator timing and max current limit set | Resistor to GND sets both oscillator charging current and maximum multiplier output: IM(MAX) = 3.75V/RSET |
| SS (13) | Soft-start control | 12µA internal current charges external capacitor; SS voltage <7.5V becomes reference for voltage amplifier during startup |
| CSET (14) | Oscillator timing capacitor | Capacitor to GND with RSET sets frequency: f = 1.5/(RSET × CSET); ramp amplitude is 5V peak-to-peak |
| VCC (15) | Supply voltage input | Operates from 11.5V–18V; UVLO at 16.5V/10.5V; requires 0.1µF ceramic + 56µF low-ESR electrolytic bypass near GND |
| GTDR (16) | High-current MOSFET gate driver | 1.5A peak totem-pole output; clamped at 15V; requires ≥5Ω series gate resistor to suppress overshoot on capacitive loads |
Key Features
| Feature | Design Value |
|---|---|
| Square-law multiplier architecture | Reduces AC gain at light load to maintain stability and keep THD <5% across 10–100% load range |
| Integrated 7.5V reference | ±0.18V worst-case accuracy over temperature - eliminates need for external reference in most PFC designs |
| 1.5A gate driver with 25ns edges | Directly drives MOSFETs up to 2nF gate capacitance without buffer stages, reducing BOM count and layout complexity |
| Multi-level protection | Combines OVP (100ns response), PKLIM (400ns), and UVLO to safeguard MOSFET, diode, and bulk capacitor under fault conditions |
| Line-noise rejection | On-chip 32kΩ resistor at IAC pin enables single-capacitor RC filter - rejects >40dB of switching noise coupled onto AC lines |
| Synchronization capability | EN/SYNC pin accepts external clock pulses up to 1.6× natural frequency - enables multi-phase interleaving or EMI spread-spectrum control |
Applications
| Industrial Motor Drives | Telecom Rectifier Modules |
|---|---|
|
Use Scenario: 3kW 3-phase rectifier with active front-end PFC stage operating from 380VAC ±10%. IC Role / Device Role / Timing Role: LT1248CS#TRPBF acts as master PFC controller, regulating boost inductor current to match sinusoidal line voltage waveform while maintaining >0.99 PF. Use Value: Enables compliance with IEC 61000-3-2 Class A harmonic limits and reduces RMS input current by 22% vs passive PFC, lowering transformer and fuse sizing. |
Use Scenario: 48V/50A telecom rectifier with universal 90–270VAC input and 1500W output. IC Role / Device Role / Timing Role: LT1248CS#TRPBF controls single-stage boost PFC to deliver regulated 382VDC bus for downstream DC/DC converters. Use Value: Achieves 94% efficiency at full load and <3% THD at 230VAC/100% load - meeting NEBS GR-63-CORE shock/vibration and thermal requirements. |
| Medical Imaging Power Supplies | EV Charging Station Preconditioning |
|
Use Scenario: CT scanner power system requiring ultra-low EMI and zero output voltage overshoot during rapid load transients. IC Role / Device Role / Timing Role: LT1248CS#TRPBF provides fast OVP response (100ns) and soft-start to prevent X-ray tube arcing during cold start. Use Value: Eliminates need for crowbar circuit; OVP trip at 7.875V ensures bulk capacitor stays within 10% of rated 450V, extending lifetime by 3× vs unprotected designs. |
Use Scenario: 7.4kW AC Level 2 EV charger with bidirectional capability and grid-support functions. IC Role / Device Role / Timing Role: LT1248CS#TRPBF serves as primary PFC controller in unidirectional mode, synchronized to grid frequency for harmonic cancellation. Use Value: Synchronization feature enables precise phase alignment with utility metering - supporting IEEE 1547 anti-islanding detection and reactive power injection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar power factor correction controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1249CS8#TRPBF | SO-8 package, simplified architecture, no RSET/CSET pins - fixed 100kHz oscillator, no synchronization, lower gate drive (0.5A) | Targeted at cost-sensitive ≤300W designs; lacks soft-start, OVP, and current-limit comparator | Choose LT1249CS8#TRPBF only for low-power, non-critical applications where board space and BOM count outweigh protection and flexibility needs. |
| UCC28180DR | Texas Instruments part; continuous conduction mode (CCM) only; 1.25A gate drive; requires external multiplier; no integrated VREF | Requires external 7.5V reference and op-amps for voltage/current loops - increases design complexity and component count | UCC28180DR suits designs already committed to TI ecosystem and needing CCM-only operation, but adds 4–6 extra passives vs LT1248CS#TRPBF's integrated solution. |
Compared with LT1249CS8#TRPBF and UCC28180DR, the LT1248CS#TRPBF offers superior integration (on-chip VREF, OVP, PKLIM, sync), higher gate drive (1.5A), and broader operating range (discontinuous/continuous modes), making it optimal for high-reliability, high-power (>500W) PFC stages where protection robustness and thermal margin are critical.
Availability
LT1248CS#TRPBF is available at Aetrix Electronics and suitable for industrial motor drives, telecom rectifier modules, medical imaging power supplies, and EV charging station preconditioning requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1248CS#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 maintains full technical and manufacturing continuity for legacy Linear power products.
The LT1248CS#TRPBF belongs to Linear's high-performance analog power controller family, engineered specifically for universal-input, high-efficiency active PFC in industrial, telecom, and medical power systems demanding low THD and robust fault protection.
FAQ
What is the maximum recommended switching frequency for LT1248CS#TRPBF?
The LT1248CS#TRPBF supports oscillator frequencies up to 300kHz, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation at 300kHz requires careful attention to gate drive layout, MOSFET selection (low Qg), and thermal management due to increased switching losses. At this frequency, RSET must be reduced to ~5.1kΩ and CSET to ~1nF to meet f = 1.5/(RSET × CSET), and the 120°C/W thermal resistance of the SO-16 package must be respected with adequate copper area and airflow.
How does the LT1248CS#TRPBF implement soft-start, and what capacitor value is recommended?
The LT1248CS#TRPBF implements soft-start via internal 12µA current charging an external capacitor on the SS pin. When SS voltage rises below 7.5V, it becomes the reference for the voltage amplifier, gradually increasing VAOUT and thus the line-current reference. A 0.01µF capacitor yields ~83ms ramp time (0.01µF × 7.5V / 12µA); larger values extend ramp time linearly. For 300W designs, 0.01µF is typical; for 1500W, 0.1µF is recommended to limit inrush stress on the boost diode and bulk capacitor.
Can LT1248CS#TRPBF operate in discontinuous conduction mode (DCM)?
Yes, the LT1248CS#TRPBF is explicitly designed to operate in both continuous and discontinuous conduction modes, as stated in the product description: "without the need for slope compensation, the LT1248 achieves far lower line current distortion with a smaller magnetic element than systems that use either peak-current detection or zero current switching approaches in both continuous and discontinuous modes of operation." Its current-mode averaging architecture inherently stabilizes DCM operation without external compensation.
What is the purpose of the 32kΩ resistor inside the IAC pin, and how should it be used?
The internal 32kΩ resistor at the IAC pin provides a defined, stable impedance for line-voltage sensing, minimizing crossover dead zone at low line voltages and enabling simple RC filtering. To reject switching noise, a capacitor (typically 1nF–10nF) is connected from IAC to GND, forming a low-pass filter with the 32kΩ resistor (e.g., 32kΩ + 1nF = 5kHz cutoff). This prevents noise from entering the multiplier and causing instability - a key differentiator versus controllers requiring external op-amp filters.
Does LT1248CS#TRPBF require external slope compensation in current-mode operation?
No, the LT1248CS#TRPBF does not require external slope compensation. Its fixed-frequency current-averaging architecture - combined with the square-law multiplier and dual high-gain amplifiers - inherently avoids subharmonic oscillation across the full load and line range. The datasheet explicitly states it achieves "far lower line current distortion … without the need for slope compensation," distinguishing it from peak-current-mode controllers like UC3854 or UCC28180 that mandate external compensation networks.
LT1248CS#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Mode:
- Average Current
- Frequency - Switching:
- 300kHz
- Current - Startup:
- 250 µA
- Voltage - Supply:
- 15.5V ~ 27V
- Operating Temperature:
- 0°C ~ 100°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-SO
LT1248CS#TRPBF FAQ
1.How can I place an order for LT1248CS#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1248CS#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 LT1248CS#TRPBF reliable?
The price and inventory of LT1248CS#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1248CS#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1248CS#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1248CS#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1248CS#TRPBF?
LT1248CS#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1248CS#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 LT1248CS#TRPBF?
For technical support, including LT1248CS#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1248CS#TRPBF requirements.
6.How does Aetrix verify that LT1248CS#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1248CS#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 LT1248CS#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1248CS#TRPBF?
All LT1248CS#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1248CS#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 LT1248CS#TRPBF part is unused and in its original packaging.
Return procedure for LT1248CS#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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