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Analog Devices Inc. LT1072CJ8
- Part No.:
- LT1072CJ8
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-CDIP (0.300", 7.62mm)
- Datasheet:
-
LT1072CJ8.pdf
- Description:
- IC REG 1.25A 8CERDIP
- Quantity:
- Payment:
- Shipping:
Inventory:2,218
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Product details
Overview
LT1072CJ8 from Linear Technology is a monolithic 1.25A current-mode switching regulator IC in an 8-lead ceramic DIP (J8) 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 operation, and 6mA quiescent current - used in isolated offline converters and battery upconverters.
For engineers reviewing the LT1072CJ8 datasheet, LT1072CJ8 pinout, LT1072CJ8 application, or LT1072CJ8 equivalent, key selection considerations include its flyback-regulated floating outputs, adaptive anti-saturation switch drive, shutdown mode (50µA), external synchronization capability (48–70kHz), and J8 package thermal rating (TJMAX = 150°C, θJA = 100°C/W).
Technical Context
The LT1072CJ8 implements current-mode control with a 40kHz oscillator, internal 1.25A/65V NPN switch, and adaptive anti-saturation driver that dynamically adjusts base drive to minimize saturation loss across load currents. Its error amplifier provides 4400 µmho transconductance and 800 V/V gain, enabling stable regulation under wide line/load transients.
Flyback regulation mode uses a dedicated 16.3V reference (±1.3V) with built-in blanking delay (1.5µs) to reject transformer leakage spikes; normal mode uses 1.244V feedback reference (±20mV). The VC pin serves quadruple function: compensation node, current limit adjustment, soft-start control, and shutdown trigger (≤0.15V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 40V - supports wide-input industrial/battery systems without external pre-regulation. |
| Switch Current Limit | 1.25A typical at 25°C - sets maximum deliverable output power in buck/boost configurations. |
| Feedback Reference Voltage | 1.244V ±20mV - defines regulated output accuracy in non-flyback topologies. |
| Flyback Reference Voltage | 16.3V ±1.3V - enables optocoupler-free isolated output regulation via transformer secondary sensing. |
| Quiescent Current | 6mA - enables high-efficiency operation at light loads without auxiliary bias winding. |
| Shutdown Supply Current | 50µA - reduces system standby power for battery-powered applications. |
| Switch Breakdown Voltage | 65V - allows direct interface with 48V bus or offline rectified inputs up to ~34V DC. |
| Thermal Resistance θJA | 100°C/W - requires careful ambient temperature management in J8 package above 1W dissipation. |
Pinout & Package
The LT1072CJ8 is housed in an 8-lead hermetic ceramic dual in-line package (J8), with 0.300-inch width, 0.100-inch lead pitch, and case temperature rating up to 150°C. Lead finish is solder-dip/plated; maximum lead temperature is 300°C for 10 seconds.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (E2) | Second Emitter Terminal | Optional emitter connection; leaving open doubles RON and halves current limit - used for derating or overload protection. |
| 2 (VSW) | Switch Collector Output | High-current NPN collector node; connects to inductor/diode in all topologies; rated 65V breakdown. |
| 3 (E1) | Primary Emitter Terminal | Mandatory ground reference for switch; must be tied to GND pin - ensures accurate current sensing and thermal path. |
| 4 (GND) | Power Ground | Common return for internal regulator, oscillator, and error amplifier; separate from E1/E2 for noise isolation. |
| 5 (VC) | Error Amplifier Output / Control | Current-output node for compensation, current limit setting, soft-start, and shutdown activation (≤0.15V). |
| 6 (FB) | Feedback Input | Accepts voltage divider signal; <0.45V selects flyback mode; 1.244V target sets output in standard regulation. |
| 7 (NC) | No Connect | Internally unused; must remain unconnected per datasheet - no routing or grounding allowed. |
| 8 (VIN) | Input Supply | Connects to raw input rail; powers internal 2.3V LDO and oscillator; supports 3–40V range with low dropout. |
Key Features
| Feature | Design Value |
|---|---|
| Flyback Regulation Mode | Enables fully floating, optocoupler-free isolated outputs using transformer secondary voltage sensing. |
| Adaptive Anti-Saturation Drive | Dynamically modulates base drive to maintain low VCE(SAT) across 0–1.25A load range - preserves efficiency at light and heavy loads. |
| External Synchronization | Accepts 48–70kHz external clock via VC pin pull-down - eliminates beat frequencies in multi-regulator systems. |
| Self-Protected Overload Handling | Integrates cycle-by-cycle current limiting, thermal foldback, and shutdown - no external fault circuitry required. |
| Minimal External Components | Operates in all standard topologies with only inductor, diode, capacitor, and two resistors - reduces BOM count and layout area. |
| Wide Topology Support | Validated for buck, boost, flyback, forward, inverting, and Cuk - one IC replaces multiple controller + switch combinations. |
Applications
| Offline AC/DC Converter | Battery-Powered Upconverter |
|---|---|
Use Scenario: 85–265V AC input rectified to ~340V DC, stepped down to 12V/1A isolated output using flyback topology. IC Role / Device Role / Timing Role: Primary-side controller and integrated switch; regulates output via reflected flyback pulse amplitude on FB pin. Use Value: Eliminates optocoupler and TL431, reducing component count by ≥4 parts while maintaining ±5% output regulation over line/load/temperature. | Use Scenario: 3.6V Li-ion battery boosted to 12V for portable instrumentation requiring low quiescent current. IC Role / Device Role / Timing Role: Boost converter controller with internal 1.25A switch; operates at 40kHz to minimize inductor size. Use Value: Delivers 12V/0.25A from 3.6V input with >85% efficiency and 6mA no-load draw - extends battery runtime vs. linear solutions. |
| Floating Dual Polarity Supply | Industrial Sensor Excitation |
Use Scenario: Generating ±15V from single 24V rail for op-amp circuits requiring galvanic isolation between analog and digital domains. IC Role / Device Role / Timing Role: Inverting buck-boost controller; uses transformer-coupled output to achieve fully floating dual rails. Use Value: Achieves ±15V @ 100mA with <1% cross-regulation drift - avoids ground loop errors in precision measurement systems. | Use Scenario: Providing stable 5V/2.5A logic supply and isolated 24V/100mA sensor excitation from 24V industrial bus. IC Role / Device Role / Timing Role: Primary-side flyback controller regulating both outputs via single transformer with auxiliary winding. Use Value: Maintains ±2% output accuracy across –40°C to +85°C ambient - meets IEC 61000-4-2/4 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 |
|---|---|---|---|
| LT1072CN8 | Same die, 8-lead plastic DIP package; θJA = 130°C/W vs. J8's 100°C/W; lower max junction temperature (100°C vs. 150°C). | Suitable for commercial-temperature, non-hermetic applications where cost is prioritized over thermal robustness. | Select LT1072CN8 when operating ambient ≤50°C and long-term reliability under thermal cycling is not critical. |
| LT1072CS8 | Same die, 8-lead SOIC-N package; θJA = 130°C/W; surface-mount compatible; no E2 pin exposed - lacks current-limit derating option. | Preferred for automated assembly and space-constrained PCBs; flyback mode remains functional but E2-based current scaling unavailable. | Choose LT1072CS8 for volume production with reflow assembly and where board area savings outweigh E2 flexibility. |
Compared with LT1072CN8 and LT1072CS8, the LT1072CJ8 offers superior thermal performance (150°C TJMAX, 100°C/W θJA) and the unique E2 pin for hardware current limit adjustment - making it optimal for high-reliability, thermally demanding, or programmable-overload applications.
Availability
LT1072CJ8 is available at Aetrix Electronics and suitable for offline AC/DC converters, battery-powered upconverters, floating dual-polarity supplies, and industrial sensor excitation requiring stable component supply across extended temperature and long-lifecycle programs.
Supply support for LT1072CJ8 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
Linear Technology Corporation (now part of Analog Devices) designs high-performance analog ICs focused on power management, precision signal conditioning, and RF solutions.
The LT1072 product line delivers monolithic high-current switching regulators with integrated switches and topology flexibility - engineered for rugged industrial, telecom, and medical power conversion where reliability and minimal external components are critical.
FAQ
What is the maximum input voltage rating for the LT1072CJ8?
The LT1072CJ8 has an absolute maximum input voltage of 40V, as specified in the Electrical Characteristics table for the standard LT1072 variant. Exceeding this voltage risks permanent damage to the internal 65V-rated switch due to avalanche stress during startup or transient events. For higher-input applications, the LT1072HVCT (60V-rated) is recommended.
Does the LT1072CJ8 support flyback topology with optocoupler-free regulation?
Yes, the LT1072CJ8 supports flyback regulation without optocouplers by using its dedicated flyback mode: pulling the FB pin below 0.45V activates the internal 16.3V reference, allowing regulation via transformer secondary voltage sensing. This achieves fully floating outputs with ±5% accuracy across line, load, and temperature - confirmed in Typical Performance Characteristics Figure TPC06.
How does the E2 pin on the LT1072CJ8 affect switch operation?
The E2 pin on the LT1072CJ8 is the second emitter terminal of the internal NPN switch. Leaving E2 unconnected doubles the effective switch ON resistance (RON) and halves the current limit from 1.25A to ~0.625A - providing hardware-based overload derating. E1 must always connect to GND; E2 is optional and used only when precise current limiting or thermal margin extension is required.
What is the purpose of the VC pin on the LT1072CJ8 beyond compensation?
The VC pin on the LT1072CJ8 serves four functions: (1) frequency compensation node, (2) current limit adjustment via external clamp voltage, (3) soft-start control using capacitor coupling, and (4) shutdown activation when pulled ≤0.15V (reducing supply current to 50µA). Its current-output architecture enables precise, externally programmable control of all three regulation parameters.
Can the LT1072CJ8 be synchronized to an external clock?
Yes, the LT1072CJ8 supports external synchronization from 48kHz to 70kHz by pulling the VC pin to ground with a narrow (<1µs) transistor-driven pulse. This avoids beat frequencies in multi-rail systems and enables EMI spread-spectrum alignment. Pulse width and amplitude must meet datasheet timing constraints (e.g., C2 = 68pF in Figure OP01) to prevent offset voltage shifts exceeding 2.2mV.
LT1072CJ8 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- *
- Package/Case:
- 8-CDIP (0.300", 7.62mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- -
- Output Configuration:
- -
- Topology:
- -
- Output Type:
- -
- Number of Outputs:
- -
- Voltage - Input (Min):
- -
- Voltage - Input (Max):
- -
- Voltage - Output (Min/Fixed):
- -
- Voltage - Output (Max):
- -
- Current - Output:
- -
- Frequency - Switching:
- -
- Synchronous Rectifier:
- -
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 8-CERDIP
LT1072CJ8 FAQ
1.How can I place an order for LT1072CJ8 through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1072CJ8 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 LT1072CJ8 reliable?
The price and inventory of LT1072CJ8 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1072CJ8 is usually 5 days.
3.What payment methods are accepted for LT1072CJ8?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1072CJ8 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1072CJ8?
LT1072CJ8 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1072CJ8 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 LT1072CJ8?
For technical support, including LT1072CJ8 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1072CJ8 requirements.
6.How does Aetrix verify that LT1072CJ8 is sourced from the original manufacturer or authorized distributors?
All LT1072CJ8 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 LT1072CJ8 meets industry standards.
7.What is the process for return or replacement of LT1072CJ8?
All LT1072CJ8 units undergo pre-shipment inspection (PSI). If there is an issue with LT1072CJ8, 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 LT1072CJ8 part is unused and in its original packaging.
Return procedure for LT1072CJ8:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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