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Analog Devices Inc. LT1270CT#PBF
- Part No.:
- LT1270CT#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-220-5
- Datasheet:
-
LT1270CT#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 8A TO220-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,492
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Product details
Overview
LT1270CT#PBF from Analog Devices (formerly Linear Technology) is a monolithic 8A high-efficiency switching regulator IC in a 5-lead TO-220 package, operating from 3.5V to 30V input, delivering up to 7.5A output in buck mode with 60kHz fixed-frequency current-mode control and internal switch saturation resistance of 0.18Ω at 100°C. It supports buck, boost, flyback, and inverting topologies and is used in PC power supplies with multiple outputs.
For engineers reviewing the LT1270CT#PBF datasheet, LT1270CT#PBF pinout, LT1270CT#PBF application, or LT1270CT#PBF equivalent, key selection considerations include its 8A internal switch rating (vs. 10A for LT1270ACT), 7mA quiescent current, flyback-regulated floating output capability, shutdown mode drawing only 100µA, and adaptive anti-saturation drive for wide load-current efficiency retention.
Technical Context
The LT1270CT#PBF integrates a high-current N-channel MOSFET switch, oscillator, current-mode PWM controller, error amplifier, and thermal/overcurrent protection circuitry on a single die. Its adaptive anti-saturation gate drive maintains efficiency across 0–7.5A load range without external compensation.
It operates in continuous conduction mode with 60kHz switching frequency, supports external synchronization via the VC pin, and features dual-reference operation: 1.244V for standard feedback and 16.3V (typ) for flyback configuration-enabling fully floating isolated outputs without optocouplers.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 8A typical at 50% duty cycle, 100°C - defines maximum sustainable output current in buck/boost configurations |
| Input Voltage Range | 3.5V to 30V - enables direct operation from 5V, 12V, and 24V rails without pre-regulation |
| Quiescent Current | 7mA - minimizes no-load power loss in always-on industrial power supplies |
| Shutdown Supply Current | 100µA typical - supports low-power standby modes in battery-backed systems |
| Reference Voltage | 1.244V ±20mV - sets output voltage accuracy in standard buck/boost via resistive divider |
| Flyback Reference Voltage | 16.3V typical - enables transformer-coupled isolated outputs without secondary-side sensing |
| Switch ON Resistance | 0.18Ω max at TJ = 100°C - determines conduction loss and thermal rise under full load |
| Switching Frequency | 60kHz ±10kHz - balances magnetics size, EMI, and efficiency for medium-power DC/DC designs |
Pinout & Package
LT1270CT#PBF is housed in a standard 5-lead plastic TO-220 package (T package), with the metal tab electrically connected to GND and thermally coupled to the die for heatsink mounting. Pin 1 is VIN, Pin 2 is VSW, Pin 3 is GND, Pin 4 is FB, Pin 5 is VC.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 1) | Power Input | Accepts 3.5V–30V unregulated input; connects directly to bulk capacitor and switch source path |
| VSW (Pin 2) | Switch Drain Output | Drives external inductor or transformer primary; carries full switched current and high dv/dt |
| GND (Pin 3) | Power & Signal Ground | Common return for internal switch, error amplifier, and thermal sensor; tied to heatsink tab |
| FB (Pin 4) | Feedback Input | Senses output voltage divider ratio; 1.244V reference sets regulation point in non-flyback modes |
| VC (Pin 5) | Control Voltage | Adjusts duty cycle and enables shutdown (≤150mV); also accepts external sync signal |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 8A Power Switch | Eliminates external MOSFET and driver, reducing BOM count and layout complexity in ≤7.5A buck converters |
| Flyback-Regulated Mode | Enables isolated outputs with primary-side regulation using 16.3V internal reference-no optocoupler or secondary-side TL431 required |
| Adaptive Anti-Saturation Drive | Maintains >85% efficiency from 0.5A to 7.5A load by dynamically optimizing gate drive timing and voltage |
| Self-Protected Operation | Includes thermal shutdown, current-limit foldback, and overvoltage clamp-prevents latch-up during overload or short-circuit events |
| External Synchronization | VC pin accepts TTL/CMOS clock input (50–70kHz), enabling noise-sensitive multi-rail systems to avoid beat frequencies |
Applications
| High Efficiency Buck Converter | PC Power Supply with Multiple Outputs |
|---|---|
Use Scenario: Step-down conversion from 12V or 24V bus to 3.3V/5V rails in embedded controllers. IC Role / Device Role / Timing Role: Primary regulating controller with integrated switch, providing current-mode PWM control and output voltage regulation. Use Value: Delivers 7.5A at 88% efficiency @2A and 86% @5A, minimizing heatsink requirements in space-constrained enclosures. |
Use Scenario: Generating +5V, +12V, and –5.2V outputs from a single 20V–24V input in desktop or industrial PC power modules. IC Role / Device Role / Timing Role: Core switching controller supporting buck, boost, and negative-buck topologies across multiple independent outputs. Use Value: Single IC replaces three discrete regulators; flyback mode enables isolated –5.2V rail without additional transformers or controllers. |
| Battery Upconverter | Negative-to-Positive Converter |
Use Scenario: Boosting 7.2V Li-ion battery pack to 12V for motor drivers or instrumentation in portable test equipment. IC Role / Device Role / Timing Role: High-current boost controller with internal 8A switch and adaptive drive for stable light-to-heavy load transition. Use Value: Achieves >85% efficiency across 1A–5A load range without external sense resistors or compensation networks. |
Use Scenario: Converting –12V supply to +12V for op-amp biasing or analog front-end circuits in telecom line cards. IC Role / Device Role / Timing Role: Inverting buck-boost controller operating in flyback-regulated mode with floating output reference. Use Value: Eliminates need for isolated DC/DC module; uses single inductor and achieves ±1% output regulation without secondary feedback. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-current switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1270ACT#PBF | 10A switch current limit (vs. 8A), same pinout and package - higher peak current capability with identical footprint | Preferred where transient loads exceed 7.5A or margin is required for long-term reliability at 7A continuous | Select LT1270ACT#PBF when design requires ≥9A pulsed output or derating headroom above 7.5A DC |
| LT3430EDD#PBF | 60V input rating, 2.75A switch, 200kHz switching, TSSOP-16 package - lower current, higher voltage, smaller footprint | Suitable for higher-input-voltage, lower-output-current applications (e.g., automotive 24V→5V/3A) where TO-220 is impractical | Choose LT3430EDD#PBF for compact layouts with VIN >30V or where thermal constraints prohibit TO-220 mounting |
Compared with LT1270ACT#PBF, the LT1270CT#PBF offers lower cost and sufficient current for 7.5A continuous designs, while LT3430EDD#PBF trades current capacity for wider input range and surface-mount compatibility-making it suitable for different voltage-class and form-factor requirements.
Availability
LT1270CT#PBF is available at Aetrix Electronics and suitable for PC power supplies with multiple outputs, battery upconverters, and negative-to-positive converters requiring stable component supply, long-lifecycle support, and TO-220-compatible thermal management.
Supply support for LT1270CT#PBF 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 power management portfolio with industry-leading reliability and documentation.
The LT1270 series belongs to Linear's monolithic high-current switching regulator product line, designed specifically for medium-power DC/DC conversion where integration, thermal robustness, and topology flexibility outweigh the need for synchronous rectification or ultra-high frequency.
FAQ
What is the maximum continuous output current achievable with the LT1270CT#PBF in buck configuration?
The LT1270CT#PBF supports up to 7.5A continuous output current in buck mode at 25°C ambient with adequate heatsinking. This is derived from its 8A typical switch current limit at 50% duty cycle and 100°C junction temperature, factoring in conduction and switching losses. Derating is required above 70°C ambient or with limited airflow.
Does the LT1270CT#PBF support flyback topology with primary-side regulation?
Yes, the LT1270CT#PBF supports flyback-regulated mode using its internal 16.3V (typ) flyback reference voltage at the FB pin. This allows fully floating isolated outputs without optocouplers or secondary-side feedback components, as confirmed in the datasheet's TA01 and TA02 application circuits.
What is the function of the VC pin on the LT1270CT#PBF, and how is it used in shutdown mode?
The VC pin on the LT1270CT#PBF serves three functions: duty-cycle control, external synchronization input, and shutdown activation. When pulled below 150mV (typ), it places the IC into shutdown mode, reducing supply current to 100µA. The datasheet specifies this threshold applies across the full temperature range and is independent of input voltage.
Can the LT1270CT#PBF be synchronized to an external clock, and what frequency range is supported?
Yes, the LT1270CT#PBF accepts external synchronization via the VC pin. It locks to TTL/CMOS-compatible clocks in the 50kHz to 70kHz range, matching its natural 60kHz switching frequency. This capability is explicitly documented in the FEATURES section and electrical characteristics table under "Switching Frequency" with synchronization enabled.
How does the adaptive anti-saturation drive in the LT1270CT#PBF improve efficiency across load conditions?
The adaptive anti-saturation drive in the LT1270CT#PBF dynamically adjusts gate drive strength and timing to prevent MOSFET saturation across varying load currents. As confirmed in the datasheet, this preserves >85% efficiency from 0.5A to 7.5A by minimizing VDS × ISW conduction loss without requiring external compensation or current-sense resistors.
LT1270CT#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-220-5
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Flyback
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.5V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 1.244V
- Voltage - Output (Max):
- 60V (Switch)
- Current - Output:
- 8A (Switch)
- Frequency - Switching:
- 60kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- TO-220-5
LT1270CT#PBF FAQ
1.How can I place an order for LT1270CT#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1270CT#PBF 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 LT1270CT#PBF reliable?
The price and inventory of LT1270CT#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1270CT#PBF is usually 5 days.
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4.How is shipping managed for LT1270CT#PBF?
LT1270CT#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1270CT#PBF 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 LT1270CT#PBF?
For technical support, including LT1270CT#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1270CT#PBF requirements.
6.How does Aetrix verify that LT1270CT#PBF is sourced from the original manufacturer or authorized distributors?
All LT1270CT#PBF 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 LT1270CT#PBF meets industry standards.
7.What is the process for return or replacement of LT1270CT#PBF?
All LT1270CT#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1270CT#PBF, 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 LT1270CT#PBF part is unused and in its original packaging.
Return procedure for LT1270CT#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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