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Analog Devices Inc. LT1241IS8#TRPBF
- Part No.:
- LT1241IS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1241IS8#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,444
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Product details
Overview
LT1241IS8#TRPBF from Analog Devices is an 8-pin, fixed-frequency, current-mode PWM controller IC optimized for off-line and DC/DC converters. It delivers 1A totem-pole output drive, operates up to 500kHz switching frequency, features 50ns current sense delay with leading-edge blanking, and includes active pull-down during undervoltage lockout for MOSFET gate control in AC-DC power supplies.
For engineers reviewing the LT1241IS8#TRPBF datasheet, LT1241IS8#TRPBF pinout, LT1241IS8#TRPBF application, or LT1241IS8#TRPBF equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply-chain support for production-grade power converter design.
Technical Context
The LT1241IS8#TRPBF implements a high-speed current-mode architecture with a trimmed oscillator (±2.5% initial accuracy at 50kHz) and tightly specified sink current (8.2mA typ), enabling stable 500kHz operation without cross-conduction spikes. Its error amplifier delivers 90dB open-loop gain and 1MHz unity-gain bandwidth, with internal 2.5V reference tied to the FB pin.
Undervoltage lockout features hysteresis (2.0V for LT1241), start-up threshold of 9.6V, and active low pull-down on both OUTPUT (Pin 6) and VREF (Pin 8) below threshold. The current sense comparator includes 100ns blanking time (at VFB = 2.5V) and a 1V clamp limiting maximum sensed voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 500kHz max output frequency (oscillator runs at 1MHz); enables compact magnetics and high-efficiency SMPS designs. |
| Output Drive Current | ±1A peak totem-pole output; directly drives power MOSFET gates without external buffer stages. |
| Start-Up Current | <250µA (170µA typ); minimizes bleed resistor losses in offline flyback/start-up circuits. |
| Reference Voltage | 5.000V ±1% (4.925–5.075V); powers RT/CT timing network and serves as precision bias for internal circuitry. |
| Current Sense Delay | 50ns typ; ensures fast overcurrent response while blanking leading-edge noise to prevent false triggering. |
| UVLO Threshold | 9.6V start-up / 7.6V minimum operating voltage with 2.0V hysteresis; prevents erratic startup during brownout conditions. |
| Output Clamp Voltage | 18V max high-level output; protects MOSFET gate oxide from overvoltage stress during transients. |
Pinout & Package
S8 package: 8-lead plastic SOIC, –40°C to 100°C operating temperature range, JEDEC MS-012AC compliant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| COMP (Pin 1) | Error amplifier output | Provides loop compensation node; sources 0.5mA / sinks 2mA min; used to clamp current sense threshold. |
| FB (Pin 2) | Inverting input of error amplifier | Internally referenced to 2.5V; accepts feedback divider signal for voltage regulation loop. |
| ISENSE (Pin 3) | Current sense comparator input | Trips when sensed voltage reaches (VCOMP−1.4V)/3; clamped at 1V max for fault limiting. |
| RT/CT (Pin 4) | Oscillator timing node | RC network sets frequency and deadtime; CT charges from VREF via RT, discharges at 8.2mA trimmed current. |
| GND (Pin 5) | Analog/digital ground reference | Single-point return for feedback, oscillator, and power paths; critical for noise immunity. |
| OUTPUT (Pin 6) | High-current PWM output | ±1A capable totem pole; actively pulled low during UVLO; 18V clamp protects MOSFET gate. |
| VCC (Pin 7) | Supply input | Operates from 7.6V to 25V; powers internal bias; quiescent current 7–10mA typical. |
| VREF (Pin 8) | 5V bandgap reference output | Supplies RT current and internal references; delivers up to 20mA; pulled low during UVLO. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control with cycle-by-cycle current limiting | Enables stable operation under wide input/output variations and simplifies loop compensation vs voltage-mode. |
| Leading-edge blanking on ISENSE | 100ns fixed blanking (at VFB = 2.5V) eliminates need for external RC filter, preserving fast fault response. |
| Trimmed oscillator frequency and sink current | ±2.5% initial frequency tolerance and 8.2mA ±0.3mA discharge current ensure consistent deadtime and duty cycle. |
| Active pull-down on OUTPUT and VREF during UVLO | Eliminates external pull-down resistors; ensures MOSFET stays off and soft-start capacitor resets reliably. |
| 1A totem-pole output with 18V clamp | Directly drives large-gate MOSFETs; clamp prevents gate overvoltage during load dump or ringing events. |
Applications
| AC-DC Off-Line Adapters | Isolated DC-DC Converters |
|---|---|
Use Scenario: 90–240VAC input, 12–24VDC output flyback or forward converter for industrial power supplies. IC Role / Device Role / Timing Role: Primary-side PWM controller generating gate drive for power MOSFET; regulates output via optocoupler feedback to FB pin. Use Value: 500kHz capability reduces transformer size; low start-up current (<250µA) improves no-load efficiency; UVLO pull-down ensures safe startup sequencing. | Use Scenario: 24–48VDC input, isolated 3.3/5/12V outputs in telecom or server power modules. IC Role / Device Role / Timing Role: Secondary-side synchronous rectifier controller or primary-side current-mode modulator in push-pull/forward topologies. Use Value: 1A output drive supports high-side MOSFETs; current sensing with blanking enables reliable overload protection; tight oscillator tolerance ensures predictable timing across temperature. |
| Industrial Motor Drives | LED Driver Power Stages |
Use Scenario: Low-power BLDC or stepper motor driver with integrated gate drive and current feedback. IC Role / Device Role / Timing Role: PWM generator for half-bridge gate drivers; senses phase current via shunt resistor at ISENSE pin. Use Value: 50ns current sense delay enables precise overcurrent cutoff; 100ns blanking suppresses switching noise; ±1A output drives bootstrap gate drivers directly. | Use Scenario: Constant-current LED driver for architectural or street lighting with wide input range. IC Role / Device Role / Timing Role: Current-mode buck or boost controller regulating LED string current via shunt sensing at ISENSE. Use Value: Cycle-by-cycle current limiting prevents LED thermal runaway; 18V output clamp protects MOSFET gate during LED open-circuit transients; 5V VREF powers auxiliary bias rails. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar current-mode PWM controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UC3842N | Slower propagation delay (100ns+), higher start-up current (1mA), no leading-edge blanking, no active UVLO pull-down. | Requires external blanking filter and pull-down resistors; less suitable for high-frequency or noise-sensitive designs. | Choose UC3842N only for legacy cost-sensitive designs where 500kHz operation and low-noise performance are not required. |
| TL5001CDR | Lower output drive (±200mA), no trimmed oscillator, wider reference tolerance (±2%), no active UVLO pull-down on VREF. | Limited to lower-power DC-DC converters; requires external components for soft-start and fault handling. | Prefer TL5001CDR for low-cost, low-power applications below 100kHz where full feature set of LT1241IS8#TRPBF is unnecessary. |
Compared with UC3842N and TL5001CDR, the LT1241IS8#TRPBF delivers superior high-frequency stability (500kHz), lower system component count (no external blanking or pull-down), and tighter parametric control-making it optimal for modern, compact, and noise-immune power converter designs.
Availability
LT1241IS8#TRPBF is available at Aetrix Electronics and suitable for AC-DC adapters, isolated DC-DC converters, and industrial motor drive power stages requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT1241IS8#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 (now part of Analog Devices, Inc. following merger with Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT1241 series belongs to Linear's legacy high-speed PWM controller product line, specifically engineered for robust, high-frequency current-mode switching power supplies in industrial and telecom infrastructure.
FAQ
What is the maximum switching frequency supported by the LT1241IS8#TRPBF?
The LT1241IS8#TRPBF supports up to 500kHz output switching frequency (oscillator runs at 1MHz). This is enabled by its 50ns current sense delay, eliminated cross-conduction, and trimmed 8.2mA oscillator sink current-allowing stable operation without external compensation. At 500kHz, the LT1241IS8#TRPBF maintains tight duty cycle control and minimal deadtime variation across temperature.
Does the LT1241IS8#TRPBF require external components for current sense noise immunity?
No-the LT1241IS8#TRPBF integrates a 100ns leading-edge blanking circuit at the ISENSE pin, eliminating the need for external RC filters in most applications. This blanking time is dynamically adjusted based on FB pin voltage and drops to zero during startup or short-circuit faults. External filtering is only required in extreme EMI environments, per the datasheet's "extreme cases" note.
How does the LT1241IS8#TRPBF handle undervoltage lockout conditions?
During undervoltage lockout, the LT1241IS8#TRPBF actively pulls both OUTPUT (Pin 6) and VREF (Pin 8) low using Darlington PNP transistors-sinking several milliamps down to ~1V. This replaces external pull-down resistors, ensures MOSFET gate remains off, and allows the VREF pull-down to reset soft-start capacitors. The LT1241IS8#TRPBF has a 9.6V start-up threshold and 7.6V minimum operating voltage with 2.0V hysteresis.
Can the LT1241IS8#TRPBF drive large-gate MOSFETs directly?
Yes-the LT1241IS8#TRPBF features a ±1A totem-pole output stage with 40ns rise / 30ns fall times into 1nF, enabling direct drive of power MOSFETs with gate charges up to ~100nC at 500kHz. Its 18V output clamp protects the MOSFET gate oxide, and active UVLO pull-down ensures safe turn-off during brownouts-removing need for external gate drivers in medium-power applications.
What is the purpose of the COMP pin on the LT1241IS8#TRPBF?
The COMP pin (Pin 1) is the error amplifier output and serves two critical roles: (1) it provides the node for external Type II or Type III loop compensation networks, and (2) it allows clamping of the current sense threshold voltage by limiting COMP voltage to <4.4V, thereby reducing maximum sensed voltage below 1V for precise current limiting. The LT1241IS8#TRPBF COMP pin sources ≥0.5mA and sinks ≥2mA.
LT1241IS8#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
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive, Isolation Capable
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 8.2V ~ 25V
- Frequency - Switching:
- 500kHz
- Duty Cycle (Max):
- 48%
- Synchronous Rectifier:
- No
- Clock Sync:
- No
- Serial Interfaces:
- -
- Control Features:
- Frequency Control
- Operating Temperature:
- -40°C ~ 100°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1241IS8#TRPBF FAQ
1.How can I place an order for LT1241IS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1241IS8#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 LT1241IS8#TRPBF reliable?
The price and inventory of LT1241IS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1241IS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1241IS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1241IS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1241IS8#TRPBF?
LT1241IS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1241IS8#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 LT1241IS8#TRPBF?
For technical support, including LT1241IS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1241IS8#TRPBF requirements.
6.How does Aetrix verify that LT1241IS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1241IS8#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 LT1241IS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1241IS8#TRPBF?
All LT1241IS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1241IS8#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 LT1241IS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1241IS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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