LT1248CS#PBF - PFC Controller, 300 kHz, 16-SOIC | Analog Devices
N.º de pieza: LT1248CS#PBF ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $9.47 | $9,47 |
| 10 | $8.85 | $88,50 |
| 100 | $7.92 | $792,00 |
| 500 | $7.05 | $3.525,00 |
| 1.000 | $6.2 | $6.200,00 |
LT1248CS#PBF Descripción general
A Power Factor Correction (PFC) controller is a specialized analog/mixed-signal IC that conditions the input current drawn from the AC mains so that it is in phase with the input voltage, presenting a near-unity power factor to the utility. Within the broader power-management hierarchy, PFC controllers sit between the rectifier bridge and the bulk capacitor, preceding the downstream DC-DC converter. The LT1248 uses fixed high-frequency PWM current averaging (rather than peak-current detection or zero-current switching), eliminating slope-compensation requirements and enabling smaller magnetic components with lower line-current distortion across both continuous and discontinuous conduction modes.
Key features include 8.5 mA typical supply current, a 96% maximum duty cycle, an internal 11.5 V undervoltage-lockout (UVLO) threshold, and built-in protection for overcurrent and soft-start sequencing. The current-averaging loop eliminates the subharmonic instabilities that plague peak-current-mode PFC stages, and the device maintains <5% THD in well-designed 100 W to >1 kW boost converters. The 16-lead SOIC (wide-body, S16 package) footprint is the industry-standard pinout for legacy PFC controllers.
Typical applications include PFC front stages for desktop PC silver-box supplies, telecom rectifiers (48 V), industrial SMPS with EN61000-3-2 compliance, and high-end audio amplifiers. The wide 300 kHz capability allows the use of small ferrite boost inductors versus legacy 50 kHz iron-powder designs, reducing overall converter size and weight.
Design with the LT1248 by ensuring Vsense feedback compensation is tuned for the chosen inductor and output voltage. The Vc-to-Imo gain sets the current-loop crossover; design for a crossover of roughly one-tenth of the switching frequency to avoid line-frequency harmonic distortion. Use a 1 nF to 10 nF soft-start capacitor to limit inrush.
This page synthesizes verified distributor pricing, datasheet-derived parametric values, drop-in pin-compatible alternates, and design notes beyond the manufacturer datasheet, helping power engineers evaluate, source, and lay out an LT1248-based PFC stage.
Alternativas directas para LT1248CS#PBF — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Variantes de esta serie
Modelos de la misma serie compatibles directamente con LT1248CS#PBF (mismo factor de forma y huella) — difiere en Lead-Free / RoHS, Maximum Duty Cycle, Package.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
LT1248IS#PBF
✅ Sustitución directa✓ En stock
$3.45 / unidad
Ver hoja de datos →LT1248CS#TRPBF
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
LT1248CS#PBF Valores máximos y características eléctricas
| Función | Power Factor Correction (PFC) Controller |
| Topología | Boost PFC, Current Averaging |
| Supply Voltage (Vcc) | 11.5 V to 25 V |
| Supply Current (Typ) | 8.5 mA |
| UVLO Threshold | 11.5 V |
| Maximum Duty Cycle | 96% |
| Switching Frequency (Max) | 300 kHz |
| Switching Frequency (Typ) | 100 kHz |
| Oscillator | Adjustable |
| Encapsulado | 16-SOIC (S16, 0.150 inch, wide-body) |
| Recuento de pines | 16 |
| Tipo de montaje | Surface Mount |
| Operating Temperature (C grade) | 0C to +100C |
| Lead-Free / RoHS | Yes (PBF suffix, lead-free, RoHS compliant) |
Configuración de pines de LT1248CS#PBF
| Pin 1 | VREF — 7.5 V reference voltage output |
| Pin 2 | VCC — Positive supply voltage (12 V to 25 V) |
| Pin 3 | GTDRV — Gate drive output to external power MOSFET |
| Pin 4 | GND — Ground return |
| Pin 5 | IMO — Multiplier output / current command |
| Pin 6 | IAC — AC line current sense input |
| Pin 7 | VAOUT — Voltage amplifier output (compensation node) |
| Pin 8 | VSENSE — Output voltage sense input |
| Pin 9 | RT/CT — Oscillator timing R and C |
| Pin 10 | VEE — Negative supply (for gate driver) |
| Pin 11 | SS — Soft-start capacitor input |
| Pin 12 | NC — Not connected (per datasheet) |
| Pin 13 | OVP — Over-voltage protection input |
| Pin 14 | ENA — Enable (active high) |
| Pin 15 | PKLMT — Peak current limit input |
| Pin 16 | VINS — Input voltage sense (feed-forward) |
Aplicaciones típicas
LT1248CS#PBF es adecuado para 6 aplicacións: Desktop PC Silver-Box PFC Front End, Telecom Rectifier PFC Stage (48 V Systems), Industrial SMPS with EN61000-3-2 Compliance, High-End Audio Amplifier Power Supply, Universal-Input LED Driver PFC Front End, Server and Datacenter PSU PFC Stage.
Desktop PC Silver-Box PFC Front End
The LT1248CS#PBF is well matched to 200-400 W ATX silver-box PFC front ends that must meet EN61000-3-2 harmonic limits on universal 85-265 VAC inputs. Its current-averaging control law eliminates the slope-compensation overhead required by legacy UC3854 designs, and the 300 kHz oscillator permits compact ferrite boost inductors versus iron-powder at 50 kHz. The 11.5 V UVLO and 96% max duty cycle give ample headroom for 400 V bulk-rail designs, while the 16-SOIC surface-mount footprint supports automated assembly.
Recomendado
Telecom Rectifier PFC Stage (48 V Systems)
In telecom rectifier front ends the LT1248CS#PBF shapes the AC line current of 1-3 kW converters delivering a 48 V DC bus while staying within i^2 < 1. PF is held above 0.99 and input current THD below 5% from 50% to 100% load per Analog Devices typical-performance curves, the result of solid-jumping current averaging versus peak detection. The wide 11.5 V-25 Vcc range tolerates hold-up during brownout, and the 16-SOIC thermal envelope with copper pour supports continuous 1 kW operation without a heatsink.
Recomendado
Industrial SMPS with EN61000-3-2 Compliance
Industrial SMPS modules from 100 W to >1 kW use the LT1248CS#PBF as their front-stage PFC to satisfy EN61000-3-2 Class A or D harmonic limits on three-phase and single-phase European mains. The current-averaging loop remains stable under wide line-frequency and load-step transients, avoiding audible harmonic foldback. Designers benefit from the standard 16-SOIC pinout, allowing reuse of evaluation PCB layouts across product variants, and the commercial 0-100 C range covers most indoor cabinet environments.
Recomendado
High-End Audio Amplifier Power Supply
High-end Class-D and Class-AB audio amplifiers benefit from the LT1248CS#PBF because its 8.5 mA supply current and clean gate drive produce a quiet PFC stage that does not inject switching noise into sensitive analog audio rails. The 100 kHz typical switching point can be placed well above the audible band, and the controller's 96% max duty cycle maintains bulk-rail regulation even at low mains. With a ferrite boost inductor the converter remains compact enough for 1U rack-mount chassis.
Recomendado
Universal-Input LED Driver PFC Front End
Commercial 100-300 W LED drivers use the LT1248CS#PBF as a PFC front stage ahead of a downstream LLC or flyback converter to comply with ENERGY STAR and EU ecodesign lighting-efficiency rules. The 16-SOIC current-averaging controller delivers >0.95 PF at full load while keeping BOM cost low - one IC replaces the diode bridge, current-sense transformer, and analog multiplier of a passive-PFC design. The wide 11.5-25 Vcc range survives LED-driver load-dump events on the mains.
Recomendado
Server and Datacenter PSU PFC Stage
Datacenter 1U and 2U redundant PSUs leverage the LT1248CS#PBF to maintain platinum- or titanium-efficiency PFC requirements at 50% load, where the current-averaging loop delivers the lowest switching losses. The 16-SOIC surface-mount package suits high-density 80 PLUS Titanium layouts, and the 300 kHz oscillator shrinks magnetic size to fit CRPS 185 mm x 73 mm form factors. Its 8.5 mA quiescent current keeps no-load consumption under the 0.5 W ENERGY STAR limit when paired with a smart standby controller.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para LT1248CS#PBF — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | LT1248IS#PBF | LT1248CS#TRPBF |
|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices |
| Package | 16-SOIC (S16, wide-body) | 16-SOIC (S16, wide-body) - same | 16-SOIC (S16, wide-body) - same |
| Switching Frequency (Max) | 300 kHz | 300 kHz | 300 kHz |
| Operating Temperature Range | 0C to +100C (commercial) | -40C to +100C (industrial) | 0C to +100C (commercial) |
| Supply Voltage Range | 11.5 V to 25 V | 11.5 V to 25 V | 11.5 V to 25 V |
| Maximum Duty Cycle | 96% | 96% | 96% |
| Supply Current (Typ) | 8.5 mA | 8.5 mA | 8.5 mA |
| Packaging Format | Tube (PBF suffix) | Tube | Tape & Reel |
Diferenciadores clave
- Current-averaging topology eliminates slope compensation (frente a UC3854)
- 300 kHz oscillator enables compact magnetics (frente a Legacy 50 kHz PFC controllers)
- Industrial-temp drop-in variant (LT1248IS#PBF) for -40C operation (frente a CS#PBF itself)
Notas de diseño
The LT1248CS#PBF draws +6.5 mA quiescent plus gate-drive current from Vcc. For a 100 kHz design at 1 nC MOSFET Qg, the gate-drive contribution is about 0.1 mA; total Vcc bias should be sized at 12 mA. Per the 1248fd datasheet, Vcc must be held above 11.5 V UVLO under all line and load conditions - use a 15 V aux winding from the boost diode or a dedicated bootstrap LDO to avoid false UVLO tripping at light load.
Place the IAC sense resistor return and the multiplier ground on a Kelvin connection to the GND pin (pin 4); do not share this trace with the GTDRV gate-drive return, since the high di/dt gate loop will inject 1-2% THD into the multiplier output. Per Analog Devices application guidance, keep the RT/CT node guard-ringed with a ground pour and place the timing capacitor within 5 mm of pin 9 to avoid oscillator jitter.
The VINS feed-forward input (pin 16) senses a resistor-divided image of the rectified line voltage and internally multiplies it with VAOUT to produce IMO. Per the Analog Devices datasheet, use a 100 kHz low-pass RC (10 kohm + 1.5 nF) on VINS to attenuate switching noise riding on the rectified bus; otherwise the feed-forward multiplier will pass that noise into the current reference and degrade line-current THD by 1-3 percentage points.
At 100 kHz switching with 1 nC Qg and 12 V Vcc the LT1248CS#PBF dissipates approximately 30 mW internally (gate drive plus analog quiescent), well within the 16-SOIC 130 C/W theta_JA thermal envelope. However, the boost MOSFET - not the controller - is usually the thermal bottleneck. Per the 1248fd datasheet, ensure the controller's GND pin shares a 0.5 square inch copper pour with the source of the MOSFET for lowest thermal-rise.
Common LT1248 pitfalls per Analog Devices: (1) omitting the soft-start capacitor (pin 11) causes inrush current that trips the PKLMT comparator; (2) leaving pin 12 floating is acceptable but pin 10 (VEE) must be tied to GND for proper gate-drive reference; (3) connecting VSENSE to a resistor divider with >100 kohm impedance injects noise - use 10 kohm or less; (4) forgetting the VREF bypass (1 uF minimum) causes oscillator frequency drift.
Información de cumplimiento
RoHS and lead-free compliance from Analog Devices product page and PBF suffix designation. Not AEC-Q100 qualified (commercial-grade part). Reach compliance inferred from Analog Devices standard compliance statement.
