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Analog Devices Inc. LT1072CN8#PBF
- Part No.:
- LT1072CN8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-DIP (0.300", 7.62mm)
- Datasheet:
-
LT1072CN8#PBF.pdf
- Description:
- IC REG BUCK BST ADJ 1.25A 8PDIP
- Quantity:
- Payment:
- Shipping:
Inventory:4,996
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Product details
Overview
LT1072CN8#PBF from Analog Devices (formerly Linear Technology) is a monolithic 1.25A current-mode switching regulator IC in an 8-lead PDIP package, supporting buck, boost, flyback, forward, inverting, and Cuk topologies. It operates from 3V to 40V input, delivers up to 20W output power, features internal 65V switch breakdown voltage, 40kHz fixed-frequency oscillator, and 6mA quiescent current - ideal for offline converters, battery upconverters, and isolated dual-polarity supplies.
For engineers reviewing the LT1072CN8#PBF datasheet, LT1072CN8#PBF pinout, LT1072CN8#PBF application, or LT1072CN8#PBF equivalent, key selection criteria include its wide 3–40V input range, flyback-regulated floating outputs without optocouplers, adaptive anti-saturation switch drive, shutdown mode drawing only 50µA, and compatibility with standard 8-pin DIP PCB footprints.
Technical Context
The LT1072CN8#PBF implements current-mode control: switch duty cycle is directly set by sensed switch current rather than output voltage error, enabling fast line transient response, simplified loop compensation, and inherent pulse-by-pulse current limiting. Its internal 1.25A/65V NPN power switch integrates oscillator, error amplifier, current-sense comparator, and adaptive anti-saturation driver.
It supports dual regulation modes: normal mode uses the 1.244V feedback reference for direct output sensing; flyback mode activates when FB is pulled below 0.45V, engaging a separate 16.3V flyback reference and blanking circuit to regulate transformer-coupled isolated outputs. The VC pin serves as error amplifier output, current limit adjust, soft-start node, and shutdown control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - enables direct operation from 5V logic rails, 12V automotive, or rectified AC inputs without pre-regulation. |
| Switch Current Limit | 1.25A typical at 25°C - defines maximum continuous load current in buck/boost; derates to 1A at 80% duty cycle per datasheet Note 3. |
| Switch Breakdown Voltage | 65V - supports flyback designs with reflected output voltages ≤65V, limiting max VIN + VREFLECTED across switch. |
| Feedback Reference Voltage | 1.244V ±20mV - sets output voltage via resistor divider; enables precise 5V, 12V, ±15V, or custom outputs with <0.5% initial accuracy. |
| Quiescent Supply Current | 6mA - ensures low no-load power loss in battery-powered systems; drops to 50µA in shutdown mode. |
| Switching Frequency | 40kHz ±5kHz - balances efficiency (low core loss) and size (moderate inductor/capacitor values); externally synchronizable to 48–70kHz. |
| Flyback Reference Voltage | 16.3V ±1.3V - used in isolated flyback mode to regulate secondary-side voltage via primary-side sensing, eliminating optocoupler need. |
Pinout & Package
The LT1072CN8#PBF is housed in an 8-lead narrow-body plastic DIP (N8) package with 0.300" width, JEDEC MS-001 compliant, rated for 0°C to 100°C operating junction temperature and θJA = 130°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (E2) | Secondary Emitter | Optional emitter tap; leaving open doubles RDS(on) and halves current limit - used for reduced-power or thermal-limited designs. |
| 2 (VSW) | Switch Collector | High-voltage switching node connected to inductor/diode; must handle full input + reflected flyback voltage. |
| 3 (E1) | Primary Emitter | Must be tied to GND pin; forms main current path with VSW; provides low-loss conduction when E2 is used. |
| 4 (VIN) | Power Input | Supplies internal 2.3V LDO and oscillator; bypass capacitor required near pin to suppress high-frequency noise. |
| 5 (GND) | Ground Reference | Analog and power ground return; connects to E1; critical for stable feedback and current-sense accuracy. |
| 6 (VC) | Error Amplifier Output | Current-output node for compensation, current limit adjustment, soft-start, and shutdown control (≤0.15V). |
| 7 (FB) | Feedback Input | Senses output voltage divider; threshold of 0.45V selects flyback regulation mode; clamp limits to 0.25–2.3V. |
| 8 (NC) | No Connect | Unbonded pin; left unconnected per datasheet - no routing or grounding required. |
Key Features
| Feature | Design Value |
|---|---|
| Flyback-regulated floating outputs | Enables fully isolated multiple-output supplies without optocouplers or extra transformer windings - reduces BOM cost and layout complexity. |
| Adaptive anti-saturation switch drive | Maintains high efficiency across 10:1 load current range by dynamically adjusting base drive to prevent transistor saturation - eliminates external drive optimization. |
| External synchronization capability | Accepts 48–70kHz external clock via VC pin, allowing noise-sensitive systems to avoid EMI bands or synchronize multiple regulators. |
| Self-protected overload handling | Integrates pulse-by-pulse current limiting, thermal foldback (untested but functional), and shutdown - eliminates need for external fault protection circuitry. |
| Wide topology support | Operates in buck, boost, flyback, forward, inverting, and Cuk configurations using same IC - reduces design reuse effort and inventory SKUs. |
Applications
| Offline AC/DC Converter | Battery-Powered Upconverter |
|---|---|
Use Scenario: Converting rectified 85–265V AC to regulated 12V/5V DC for industrial controls or IoT gateways. IC Role / Device Role / Timing Role: Primary-side controller in discontinuous conduction mode (DCM) flyback topology, regulating output via primary-side sensing. Use Value: Achieves >75% efficiency at 25W with no optocoupler, reducing component count and improving reliability over traditional TL431+opto designs. | Use Scenario: Boosting single-cell Li-ion (3.0–4.2V) to 5V/2.5A for USB peripherals or portable instrumentation. IC Role / Device Role / Timing Role: High-efficiency boost converter with integrated 1.25A switch, minimizing external FET and driver requirements. Use Value: Delivers full 2.5A at 5V from 3.3V input with <6mA quiescent current - extends battery runtime by >20% vs. discrete switch solutions. |
| Dual-Polarity Op-Amp Supply | Isolated Industrial Sensor Interface |
Use Scenario: Generating ±15V from 5V logic rail for precision op-amps in data acquisition systems. IC Role / Device Role / Timing Role: Inverting buck-boost regulator providing negative output; paired with standard boost for positive rail. Use Value: Eliminates need for charge-pump ICs or transformer-based modules - achieves ±15V @ 100mA with <1% cross-regulation and no magnetic components. | Use Scenario: Powering isolated analog sensors in hazardous environments (e.g., 4–20mA transmitters) with galvanic separation. IC Role / Device Role / Timing Role: Flyback controller generating fully floating 5V/12V outputs referenced to sensor ground, not system ground. Use Value: Withstands >2.5kV isolation barrier; regulates secondary outputs within ±3% without feedback winding - meets IEC 61000-4-5 surge immunity requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1071CT#PBF | 2.5A switch current rating, identical 40V max input, same 8-pin DIP package, but higher peak current capability. | Preferred for >1.25A continuous loads (e.g., 5V@2A logic supplies); requires larger inductor and catch diode due to higher current. | Select when output current exceeds 1.25A and board space allows upgraded magnetics; pinout and compensation network are identical. |
| LM2576HVS-ADJ | 3A switch, 60V input, 52kHz frequency, fixed internal compensation, no flyback mode, TO-220-5 package. | Suitable for non-isolated buck applications only; lacks flyback regulation, VC programmability, and multi-topology flexibility. | Choose for cost-sensitive, high-current buck-only designs where isolation and topology flexibility are unnecessary. |
Compared with LT1071CT#PBF, the LT1072CN8#PBF offers lower current rating but identical footprint and feature set for sub-1.25A designs; versus LM2576HVS-ADJ, it trades higher integration (flyback mode, VC control) for lower max current and DIP packaging - making it optimal for compact, isolated, or multi-topology prototyping.
Availability
LT1072CN8#PBF is available at Aetrix Electronics and suitable for offline AC/DC converters, battery-powered upconverters, dual-polarity op-amp supplies, and isolated industrial sensor interfaces requiring stable component supply and long-term obsolescence management.
Supply support for LT1072CN8#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, inheriting its legacy of high-performance analog and power management ICs with emphasis on precision, reliability, and application-focused design.
The LT1072 product line was engineered for high-efficiency, multi-topology DC-DC conversion in space-constrained industrial, telecom, and test equipment - prioritizing integration (internal switch, oscillator, protection) and isolation capability over raw current rating.
FAQ
What is the maximum input voltage supported by the LT1072CN8#PBF?
The LT1072CN8#PBF supports a maximum input voltage of 40V, as specified in the Absolute Maximum Ratings table for the standard LT1072 variant. Exceeding this voltage risks switch breakdown (65V rating applies to the collector-emitter blocking capability, not sustained input). For 60V input applications, the LT1072HV variant must be used.
Can the LT1072CN8#PBF generate isolated outputs without an optocoupler?
Yes, the LT1072CN8#PBF supports flyback-regulated mode: when the FB pin voltage drops below 0.45V, it engages a dedicated 16.3V flyback reference and blanking circuit that regulates output voltage by sensing the reflected flyback pulse - enabling fully isolated, optocoupler-free designs with transformer-coupled secondaries.
How does the VC pin function in the LT1072CN8#PBF?
The VC pin on the LT1072CN8#PBF serves four critical functions: (1) error amplifier output for compensation network connection, (2) current limit adjustment via external clamping, (3) soft-start control using a capacitor, and (4) shutdown activation when pulled below 0.15V - reducing supply current to 50µA while maintaining regulation readiness.
What is the purpose of the E2 pin on the LT1072CN8#PBF?
The E2 pin on the LT1072CN8#PBF is a secondary emitter terminal for the internal NPN switch. Leaving E2 unconnected doubles the effective switch ON resistance and halves the current limit - a deliberate design option to reduce power dissipation during overload conditions or to thermally derate the device in small packages like the N8 DIP without changing the PCB layout.
Does the LT1072CN8#PBF support external frequency synchronization?
Yes, the LT1072CN8#PBF can be externally synchronized to frequencies between 48kHz and 70kHz by pulling the VC pin to ground with a narrow (<1µs) pulse from an external transistor. This allows EMI reduction by avoiding sensitive frequency bands or synchronizing multiple regulators in a system - with minimal impact on offset voltage (≈2.2mV shift under typical conditions).
LT1072CN8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-DIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, Cuk, Flyback, Forward Converter
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 40V
- Voltage - Output (Min/Fixed):
- 1.25V
- Voltage - Output (Max):
- 65V (Switch)
- Current - Output:
- 1.25A (Switch)
- Frequency - Switching:
- 40kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 100°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-PDIP
LT1072CN8#PBF FAQ
1.How can I place an order for LT1072CN8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1072CN8#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 LT1072CN8#PBF reliable?
The price and inventory of LT1072CN8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1072CN8#PBF is usually 5 days.
3.What payment methods are accepted for LT1072CN8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1072CN8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1072CN8#PBF?
LT1072CN8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1072CN8#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 LT1072CN8#PBF?
For technical support, including LT1072CN8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1072CN8#PBF requirements.
6.How does Aetrix verify that LT1072CN8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1072CN8#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 LT1072CN8#PBF meets industry standards.
7.What is the process for return or replacement of LT1072CN8#PBF?
All LT1072CN8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1072CN8#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 LT1072CN8#PBF part is unused and in its original packaging.
Return procedure for LT1072CN8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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