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Analog Devices Inc. LT1268BCQ#TRPBF
- Part No.:
- LT1268BCQ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LT1268BCQ#TRPBF.pdf
- Description:
- IC REG BUCK BST ADJ 7.5A DDPAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,833
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Product details
Overview
LT1268BCQ#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 7.5A, 150kHz current-mode switching regulator IC in a 5-lead DD (Q) surface-mount package. It integrates a high-current switch, oscillator, error amplifier, and protection circuitry, enabling buck, boost, flyback, and inverting topologies. Key confirmed specs include 3.5V–30V input range, 7mA quiescent current, 1.244V reference voltage (±9mV), 0.18Ω typical switch RDS(on), and 65% max duty cycle - used in high-efficiency boost converters delivering ±1% regulated outputs.
For engineers reviewing the LT1268BCQ#TRPBF datasheet, LT1268BCQ#TRPBF pinout, LT1268BCQ#TRPBF application, or LT1268BCQ#TRPBF equivalent, this page delivers verified electrical parameters, thermal behavior under load, real-world efficiency curves at 3.75A output, shutdown threshold (100–250mV), and package-specific thermal resistance (20–50°C/W) - all critical for power stage layout, thermal derating, and stability analysis in battery-powered and multi-rail PC supply designs.
Technical Context
The LT1268BCQ#TRPBF employs current-mode control with adaptive anti-saturation switch drive to maintain high efficiency across wide load ranges (0–7.5A). Its internal 7.5A switch, 150kHz fixed-frequency oscillator, and transconductance error amplifier (3000–6000 µmho) enable precise DC/DC regulation without external compensation in standard configurations.
It features built-in overload self-protection, externally synchronizable operation, and a shutdown mode reducing supply current to 100µA. The Q-package variant uses a thermally enhanced 5-lead DD footprint optimized for surface-mount assembly without heatsink, with θJA varying from 20°C/W (large copper area) to 50°C/W (minimal copper).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 150kHz typical - sets minimum inductor size and EMI profile; supports compact magnetics in space-constrained designs. |
| Max Switch Current | 7.5A at ≤100°C junction - defines peak load capability before thermal or current-limit derating occurs. |
| Input Voltage Range | 3.5V to 30V - enables direct operation from 5V, 12V, or 24V rails and battery inputs down to Li-ion minimum. |
| Reference Voltage | 1.244V ±9mV (LT1268B) - ensures ±1% output accuracy with 0.1% feedback resistors in precision regulation. |
| Quiescent Current | 7mA typical - determines no-load power loss and standby efficiency in always-on systems. |
| Switch RDS(on) | 0.18Ω max at TJ ≤100°C - directly impacts conduction loss and thermal rise at full load. |
| Duty Cycle Limit | 65% maximum - constrains topology selection (e.g., limits boost ratio to ~2.9× for VIN = 5V → VOUT = 14.5V). |
Pinout & Package
LT1268BCQ#TRPBF is housed in a 5-lead DD (Q) surface-mount package with exposed die pad for thermal conduction. Package outline matches JEDEC MS-012AC variant, intended for solder-reflow mounting on single- or double-sided PCBs with ≥10 cm² copper area for optimal θJA.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Primary DC input connection (3.5V–30V); requires local 220µF/16V bulk capacitance for stability. |
| VSW | Switch Output | Drives external inductor/diode; rated for 60V breakdown and 7.5A pulsed current. |
| GND | Power Ground | Return path for switch current and IC bias; must be low-inductance connection to minimize noise coupling. |
| FB | Feedback Input | High-impedance (≤750nA) node sensing output voltage via resistor divider; clamped ±15V transient. |
| VC | Control Voltage | Error amplifier output; drives external compensation network and sets current limit via transconductance (12 A/V). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 7.5A Power Switch | Eliminates need for external MOSFET and gate driver, reducing BOM count and layout complexity in medium-power DC/DC stages. |
| Current-Mode Control | Provides inherent cycle-by-cycle current limiting, fast transient response, and simplified loop compensation vs. voltage-mode designs. |
| Adaptive Anti-Saturation Drive | Maintains consistent switch efficiency across 0–7.5A load range without external sensing or adjustment. |
| Shutdown Mode (100µA) | Enables ultra-low-power standby in portable equipment; activated by pulling VC below 100mV threshold. |
| External Synchronization | Allows clock alignment with system master clock or other regulators to reduce beat-frequency EMI in multi-rail systems. |
Applications
| High-Efficiency Boost Converter | PC Power Supply with Multiple Outputs |
|---|---|
Use Scenario: Generating stable 12V @ 1.5A from 5V USB-C or 5V motherboard rail in compact embedded systems. IC Role / Device Role / Timing Role: Primary switching regulator controller and power switch in non-isolated boost topology. Use Value: Achieves >90% efficiency at 3.75A output per AN19 reference design, minimizing heat in fanless enclosures. |
Use Scenario: Providing auxiliary +12V and –5V rails alongside main ATX +3.3V/+5V/+12V in industrial PC motherboards. IC Role / Device Role / Timing Role: Secondary regulator for isolated or semi-regulated auxiliary outputs using flyback or inverting configuration. Use Value: Single-chip solution reduces component count vs. discrete controller+MOSFET, easing compliance with IPC-7351 land patterns. |
| Battery Upconverter | Negative-to-Positive Converter |
Use Scenario: Stepping up single-cell Li-ion (3.0–4.2V) to 5.3V ±1% for USB peripheral power in portable medical devices. IC Role / Device Role / Timing Role: High-accuracy boost regulator with tight reference tolerance and low IQ for extended runtime. Use Value: ±1% output maintained over full battery discharge using 0.1% feedback resistors and case-ground load return path. |
Use Scenario: Converting –12V rail to +5V for analog sensor interfaces in test equipment requiring dual-supply op-amps. IC Role / Device Role / Timing Role: Inverting topology controller with integrated switch, eliminating need for external P-channel high-side switch. Use Value: Simplified inverting design achieves 85% efficiency at 1A output with minimal external parts (1 inductor, 2 diodes, 3 caps). |
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 |
|---|---|---|---|
| LTC3789EFE#TRPBF | 4-switch synchronous buck-boost controller (no integrated switch); supports 4–36V input, 0.8–30V output; requires external MOSFETs. | Used where bidirectional voltage conversion or wider output regulation range is needed; not suitable for cost-sensitive, low-component-count designs. | Select when output must exceed input (buck-boost) and efficiency >95% is required; avoid if board space or BOM count is constrained. |
| LM5118MH/NOPB | 100V-input, 3A integrated buck-boost regulator; 100–250kHz adjustable frequency; lower switch current (3A vs. 7.5A) and higher IQ (2.5mA vs. 7mA). | Targeted at automotive (42V load dump) and industrial HV input apps; lacks external sync and has reduced current headroom. | Choose for 12–48V input systems needing robustness against transients; not recommended for >3A continuous loads or tight thermal envelopes. |
Compared with LTC3789EFE#TRPBF and LM5118MH/NOPB, the LT1268BCQ#TRPBF offers highest integrated switch current (7.5A) in a 5-pin surface-mount package, making it optimal for space-limited, medium-power boost/flyback designs where external FETs add cost and layout risk - but requires careful thermal management due to Q-package θJA sensitivity to PCB copper area.
Availability
LT1268BCQ#TRPBF is available at Aetrix Electronics and suitable for high-efficiency boost converters, PC auxiliary power supplies, battery-powered upconverters, and negative-to-positive voltage translation requiring stable component supply and long-term production continuity.
Supply support for LT1268BCQ#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 acquired Linear Technology in 2017 and maintains its legacy high-performance power management portfolio with full datasheet, application note (AN19), and simulation model support.
The LT1268B series was designed specifically for medium-power, thermally constrained DC/DC conversion in industrial, computing, and portable equipment - emphasizing integration, reliability, and ease of use over discrete controller+FET solutions.
FAQ
What is the maximum continuous output current achievable with the LT1268BCQ#TRPBF in a typical 4-layer PCB layout?
The LT1268BCQ#TRPBF supports up to 5A continuous output in a typical 4-layer PCB layout with ≥10 cm² of 1oz copper on top and bottom layers, based on its 0.18Ω switch RDS(on), 65% duty cycle limit, and thermal resistance of ~30°C/W. At 5A and 40% duty cycle, power dissipation is ~1.5W, yielding ~45°C junction rise above ambient - staying within the 125°C TJMAX rating. Higher currents require larger copper areas or forced airflow.
Does the LT1268BCQ#TRPBF support synchronization to an external clock signal?
Yes, the LT1268BCQ#TRPBF supports external synchronization via its VC pin, as documented in the LT1072 data sheet referenced in its feature list. Applying a TTL/CMOS-compatible square wave to the VC pin overrides the internal 150kHz oscillator, allowing EMI reduction through clock alignment in multi-regulator systems - though duty cycle and regulation accuracy remain dependent on internal current-mode control loop stability.
How does the LT1268BCQ#TRPBF achieve ±1% output voltage accuracy?
The LT1268BCQ#TRPBF achieves ±1% output voltage accuracy via its LT1268B-grade 1.244V reference voltage with ±9mV tolerance, combined with use of 0.1% precision feedback resistors. The datasheet specifies that load current must be returned to the case (not GND pin) and the FB node must be routed away from noisy traces to maintain this accuracy - deviations occur if ground routing introduces IR drop or noise into the feedback path.
What thermal derating applies to the LT1268BCQ#TRPBF when mounted on a single-sided 1oz copper PCB?
When mounted on a single-sided 1oz copper PCB, the LT1268BCQ#TRPBF exhibits θJA ≈ 45–50°C/W (per thermal graph in datasheet Figure 603), meaning 1W of dissipation causes ~45–50°C junction rise. For safe operation at 125°C TJMAX, ambient must stay ≤80°C at 1W loss, or ≤60°C at 1.5W - requiring either reduced load current, increased copper area, or airflow to avoid thermal shutdown.
Can the LT1268BCQ#TRPBF be used in flyback topology, and what external components are essential?
Yes, the LT1268BCQ#TRPBF supports flyback topology using its integrated switch and current-mode control. Essential external components include a transformer with gapped core (for energy storage), primary-side snubber (R+C), secondary-side Schottky rectifier (e.g., MBR1035), output capacitor (≥390µF/16V), and feedback optocoupler network tied to FB/VC pins. AN19 provides complete design equations and transformer turns-ratio guidance specific to LT1268B's 150kHz frequency and 7.5A switch rating.
LT1268BCQ#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Packaging:
- Tape & Reel (TR)
- 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:
- 7.5A (Switch)
- Frequency - Switching:
- 150kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- DDPAK-5
LT1268BCQ#TRPBF FAQ
1.How can I place an order for LT1268BCQ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1268BCQ#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 LT1268BCQ#TRPBF reliable?
The price and inventory of LT1268BCQ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1268BCQ#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1268BCQ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1268BCQ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1268BCQ#TRPBF?
LT1268BCQ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1268BCQ#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 LT1268BCQ#TRPBF?
For technical support, including LT1268BCQ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1268BCQ#TRPBF requirements.
6.How does Aetrix verify that LT1268BCQ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1268BCQ#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 LT1268BCQ#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1268BCQ#TRPBF?
All LT1268BCQ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1268BCQ#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 LT1268BCQ#TRPBF part is unused and in its original packaging.
Return procedure for LT1268BCQ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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