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Analog Devices Inc. LT1269CQ#PBF
- Part No.:
- LT1269CQ#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LT1269CQ#PBF.pdf
- Description:
- IC REG BUCK BOOST ADJ 4A DDPAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:4,025
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Product details
Overview
LT1269CQ#PBF from Analog Devices (formerly Linear Technology) is a monolithic 100kHz, 4A high-efficiency switching regulator in a 5-lead plastic DD package. It integrates a high-current switch, oscillator, current-mode control, and thermal/overload protection, supporting buck, boost, flyback, and inverting topologies. Designed for PC power supplies with multiple outputs and battery up-converters, it operates from 3.5V to 30V input and delivers up to ~15W in buck mode at 5V output.
For engineers reviewing the LT1269CQ#PBF datasheet, LT1269CQ#PBF pinout, LT1269CQ#PBF application, or LT1269CQ#PBF equivalent, key selection criteria include its 100kHz switching frequency, 4A internal switch current limit, 7mA quiescent current, flyback-regulated floating-output capability, and shutdown mode drawing only 100µA - all critical for compact, high-efficiency DC-DC designs requiring stable regulation across wide input ranges.
Technical Context
The LT1269CQ#PBF uses current-mode switching architecture with adaptive anti-saturation switch drive, enabling wide load-current range without efficiency loss. Its error amplifier features 1.244V reference voltage (±20mV), 4400µmho transconductance, and clamp voltages (1.8–2.3V high, 0.25–0.52V low) to ensure stable feedback loop behavior under transient conditions.
It supports external synchronization via the VC pin and includes dedicated flyback regulation circuitry with 16.3V flyback reference voltage (±1.3V) and 6.8V reference change over 0.05–1mA FB current. Shutdown threshold is 0.9V typical on VC, reducing supply current to 100µA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 100kHz typical - enables smaller magnetics than 60kHz LT1271, balancing EMI and efficiency. |
| Internal Switch Current Limit | 4A typical at 50% duty cycle - supports ≥3.5A continuous output in buck mode with margin. |
| Reference Voltage | 1.244V ±20mV - sets output voltage accuracy in standard buck/boost configurations. |
| Quiescent Current | 7mA typical - minimizes no-load power loss in always-on systems. |
| Shutdown Supply Current | 100µA typical - enables ultra-low-power standby in battery-powered applications. |
| Flyback Reference Voltage | 16.3V ±1.3V - defines regulated floating output voltage in flyback topology. |
| Input Voltage Range | 3.5V to 30V - accommodates 5V, 12V, and 24V industrial/battery rails without pre-regulation. |
Pinout & Package
LT1269CQ#PBF is housed in a 5-lead plastic DD (Q) package with exposed copper heat sink on bottom. Thermal resistance is θJA = 30°C/W (with 0.75 in² 1 oz copper), enabling >3W dissipation at 100°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Connects to unregulated DC input (3.5V–30V); feeds internal bias and switch driver. |
| VSW | Switch Output | Drives external inductor/diode; carries full switched current; requires low-inductance layout. |
| GND | Power Ground | Common return for switch, feedback amplifier, and thermal pad; must be low-impedance. |
| FB | Feedback Input | Senses output voltage divider; regulates to 1.244V reference; high-impedance (750nA max). |
| VC | Control Voltage | Accepts 0.5–1.25V for shutdown (≤0.9V), burst mode (open), or external compensation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 4A Power Switch | Eliminates external MOSFET and gate driver, reducing BOM count and PCB area in buck/boost designs. |
| Flyback-Regulated Floating Outputs | Enables isolated dual-output or negative-to-positive conversion without optocoupler or secondary-side controller. |
| Adaptive Anti-Saturation Drive | Maintains high efficiency (>90%) from light load (0.4A) to full load (3A) without external compensation. |
| Self-Protected Overload Handling | Combines current limiting, thermal shutdown, and safe operating area (SOA) protection - no external foldback required. |
| External Synchronization Capability | VC pin accepts external clock signal to align switching frequency with system timing or reduce beat frequencies. |
Applications
| PC Power Supply with Multiple Outputs | Battery Up-Converter |
|---|---|
Use Scenario: Desktop or embedded PC motherboard requiring +5V, +12V, and –12V rails from a single 12V or 24V input. IC Role / Device Role / Timing Role: LT1269CQ#PBF configured in flyback mode generates isolated +5V and –12V simultaneously using one transformer winding set. Use Value: Achieves >90% efficiency at 1.5A per rail while eliminating need for separate regulators or optocouplers. | Use Scenario: Portable medical device powered by 3.7V Li-ion battery needing stable 5V/3A for USB peripherals and microcontroller. IC Role / Device Role / Timing Role: LT1269CQ#PBF operates in boost configuration to step up battery voltage (3.5–4.2V) to regulated 5V output. Use Value: Delivers 3A continuous output with 7mA quiescent current, extending runtime versus linear solutions. |
| Negative-to-Positive Buck-Boost Converter | High Efficiency Buck Converter |
Use Scenario: Industrial sensor node with –12V legacy supply requiring +5V logic rail for new digital interface. IC Role / Device Role / Timing Role: LT1269CQ#PBF configured in inverting buck-boost topology converts –12V input to +5V output. Use Value: Uses single IC and standard magnetics - avoids discrete charge-pump limitations and poor regulation. | Use Scenario: Factory automation controller powered from 24V DC bus needing efficient 5V/3A for FPGA and I/O. IC Role / Device Role / Timing Role: LT1269CQ#PBF in synchronous buck mode (with external diode) delivers regulated 5V from 24V input. Use Value: Supports 3.5A output (≈17.5W) with <0.33Ω switch RDS(on), minimizing conduction loss at high current. |
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 |
|---|---|---|---|
| LT1271CQ#PBF | 60kHz switching frequency, identical pinout and package, 4A switch, but lower frequency limits inductor size reduction. | Better suited for EMI-sensitive environments where lower frequency simplifies filtering. | Select LT1271CQ#PBF when lower EMI and relaxed inductor size constraints outweigh efficiency gains from higher frequency. |
| LT1374CS#PBF | 500kHz operation, 4.5A switch, SO-8 package, requires external MOSFET driver and bootstrap components. | Higher frequency enables smaller magnetics but demands more complex layout and external FET selection. | Choose LT1374CS#PBF when board space is critical and design team has experience managing high-frequency buck layouts. |
Compared with LT1271CQ#PBF and LT1374CS#PBF, the LT1269CQ#PBF offers optimal balance of integration (internal 4A switch), moderate 100kHz frequency (smaller magnetics than LT1271, less layout sensitivity than LT1374), and proven robustness in multi-output flyback designs - making it ideal for cost-sensitive, medium-power industrial converters.
Availability
LT1269CQ#PBF is available at Aetrix Electronics and suitable for PC power supplies with multiple outputs, battery up-converters, negative-to-positive buck-boost converters, and high-efficiency buck converters requiring stable component supply and long-term industrial availability.
Supply support for LT1269CQ#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 maintains full product support, datasheets, and application notes for legacy Linear parts including the LT1269 series.
The LT1269CQ#PBF belongs to Linear's monolithic high-power switching regulator family, designed specifically for compact, high-efficiency DC-DC conversion in industrial, computing, and battery-powered systems where integration, reliability, and wide input range are essential.
FAQ
What is the maximum continuous output current achievable with the LT1269CQ#PBF in buck configuration?
The LT1269CQ#PBF supports up to approximately 3.5A continuous output in buck mode, derived from its 4A internal switch current limit and typical 100kHz operation. Actual output depends on input voltage, output voltage, thermal management (θJA = 30°C/W with proper copper), and external component selection. At 5V output from 12V input, sustained 3A is readily achievable with >90% efficiency.
Does the LT1269CQ#PBF require an external diode in boost configuration?
Yes, the LT1269CQ#PBF requires an external Schottky diode (e.g., MBR340) in boost configuration to provide the freewheeling path during switch off-time. The internal switch is N-channel and cannot conduct reverse current; the diode must be rated for ≥1.5× peak inductor current and low forward voltage to maintain efficiency.
Can the LT1269CQ#PBF be used in flyback mode with isolated outputs?
Yes, the LT1269CQ#PBF supports fully floating flyback-regulated outputs using its dedicated flyback amplifier and 16.3V reference. When configured with a center-tapped or dual-winding transformer, it regulates secondary-side outputs without optocouplers or TL431 circuits - confirmed in LT1271/LT1269 datasheet Figure TA04.
What is the purpose of the VC pin on the LT1269CQ#PBF?
The VC pin on the LT1269CQ#PBF serves three functions: (1) shutdown control (≤0.9V disables switching, drawing only 100µA), (2) burst mode enable (open circuit), and (3) external compensation node. It is not a standard voltage feedback input but a control interface tied to the internal transconductance amplifier and shutdown comparator.
Is the LT1269CQ#PBF pin-compatible with the LT1271CQ#PBF?
Yes, the LT1269CQ#PBF is pin-compatible with the LT1271CQ#PBF - both use identical 5-lead DD (Q) package, same pinout (VIN-VSW-GND-FB-VC), and share identical absolute maximum ratings and functional block diagram. The only differences are switching frequency (100kHz vs. 60kHz) and minor variations in current limit vs. duty cycle curves.
LT1269CQ#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Down, Step-Up/Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck, Boost, 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:
- 4A (Switch)
- Frequency - Switching:
- 100kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 100°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DDPAK-5
LT1269CQ#PBF FAQ
1.How can I place an order for LT1269CQ#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1269CQ#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 LT1269CQ#PBF reliable?
The price and inventory of LT1269CQ#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1269CQ#PBF is usually 5 days.
3.What payment methods are accepted for LT1269CQ#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1269CQ#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1269CQ#PBF?
LT1269CQ#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1269CQ#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 LT1269CQ#PBF?
For technical support, including LT1269CQ#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1269CQ#PBF requirements.
6.How does Aetrix verify that LT1269CQ#PBF is sourced from the original manufacturer or authorized distributors?
All LT1269CQ#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 LT1269CQ#PBF meets industry standards.
7.What is the process for return or replacement of LT1269CQ#PBF?
All LT1269CQ#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1269CQ#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 LT1269CQ#PBF part is unused and in its original packaging.
Return procedure for LT1269CQ#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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