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Analog Devices Inc. LT1268CQ#TRPBF
- Part No.:
- LT1268CQ#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- TO-263-6, D2PAK (5 Leads + Tab), TO-263BA
- Datasheet:
-
LT1268CQ#TRPBF.pdf
- Description:
- IC REG BUCK BST ADJ 7.5A DDPAK-5
- Quantity:
- Payment:
- Shipping:
Inventory:1,168
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Product details
Overview
LT1268CQ#TRPBF from Analog Devices (formerly Linear Technology) is a monolithic 7.5A, 150kHz switching regulator IC in a 5-lead DD (Q) surface-mount package. It integrates a high-current switch, oscillator, current-mode control, and thermal/overcurrent protection. Designed for buck, boost, flyback, and inverting topologies, it operates from 3.5V to 30V input and delivers regulated outputs in high-efficiency DC-DC converters for battery-powered systems.
For engineers reviewing the LT1268CQ#TRPBF datasheet, LT1268CQ#TRPBF pinout, LT1268CQ#TRPBF application, or LT1268CQ#TRPBF equivalent, key selection criteria include its 7.5A internal switch current limit, 150kHz fixed switching frequency, 1.244V reference voltage accuracy, adaptive anti-saturation drive, and shutdown mode drawing only 100µA - critical for portable and industrial power designs requiring robust, low-component-count regulation.
Technical Context
The LT1268CQ#TRPBF implements current-mode control with an integrated 7.5A N-channel MOSFET switch and adaptive anti-saturation gate drive, enabling stable operation across wide load ranges without efficiency loss. Its error amplifier features 4400 µmho transconductance and ±9mV reference tolerance (LT1268B variant), supporting ±1% output accuracy with 0.1% external resistors.
It supports external synchronization via the VC pin, includes undervoltage lockout (UVLO) with adjustable threshold, and provides internal thermal shutdown at 140°C junction temperature. The Q-package's thermal resistance (θJA = 20–50°C/W depending on PCB copper area) directly constrains continuous switch current - e.g., 5A max at 40% duty cycle with 30°C/W θJA and 1.5W switch loss.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 7.5A typical at ≤100°C; derates to 6.5A at 65% duty cycle - defines maximum sustainable output current before foldback. |
| Switching Frequency | 150kHz typical (120–180kHz range) - balances efficiency, EMI, and external component size in compact designs. |
| Reference Voltage | 1.244V ±9mV (LT1268B grade) - enables ±1% output regulation using precision feedback resistors. |
| Quiescent Current | 7mA typical - minimizes no-load power loss in always-on or low-duty-cycle applications. |
| Shutdown Current | 100µA typical - ensures ultra-low standby consumption for battery longevity. |
| Input Voltage Range | 3.5V to 30V - supports wide-input industrial, automotive, and multi-cell battery inputs without pre-regulation. |
| Switch RDS(on) | 0.18Ω max at 100°C - determines conduction loss and thermal rise under full load. |
Pinout & Package
LT1268CQ#TRPBF is housed in a 5-lead DD (Q) surface-mount package with exposed thermal pad. Pin layout is standardized across LT1268 variants: VIN (1), VSW (2), GND (3), FB (4), VC (5).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power Input | Primary supply input (3.5V–30V); connects to bulk capacitor and feeds internal bias circuitry. |
| VSW | Switch Drain | High-side switch output node; connects to inductor in buck/boost/flyback configurations. |
| GND | Power & Signal Ground | Common return for switch, feedback, and control circuits; requires low-impedance PCB connection to minimize noise. |
| FB | Feedback Input | Resistor-divider input sensing output voltage; compares to 1.244V reference to regulate duty cycle. |
| VC | Control Voltage | Current-mode control input; sets peak inductor current and enables external sync or shutdown (≤150mV). |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 7.5A Power Switch | Eliminates external MOSFET and driver, reducing BOM count and layout complexity in high-current DC-DC stages. |
| Adaptive Anti-Saturation Drive | Maintains high efficiency across 0–100% load range by dynamically optimizing gate drive to prevent MOSFET saturation. |
| Current-Mode Control Architecture | Provides inherent cycle-by-cycle current limiting, fast transient response, and stable operation with minimal output capacitance. |
| External Synchronization Capability | Allows VC pin to accept external clock signal, enabling noise-sensitive systems to avoid EMI peaks or synchronize multiple regulators. |
| Self-Protected Overload Handling | Combines thermal shutdown (140°C), overcurrent foldback, and UVLO to survive fault conditions without external protection circuitry. |
Applications
| Battery-Powered Boost Converter | Industrial PC Power Supply |
|---|---|
Use Scenario: Step-up conversion from single Li-ion (3.7V) to 5.3V ±1% for USB peripherals in portable test equipment. IC Role / Device Role / Timing Role: Primary regulating controller implementing current-mode boost topology with 150kHz switching. Use Value: Delivers 3.75A output with >90% efficiency at 5V input, enabled by 7.5A internal switch and low 7mA quiescent current. | Use Scenario: Generating +12V and –12V rails from 5V motherboard supply in ruggedized industrial PCs. IC Role / Device Role / Timing Role: Dual-role controller: boost converter for +12V and inverting regulator for –12V, sharing same IC footprint. Use Value: Reduces board space and component count vs discrete solutions while maintaining tight regulation via 1.244V reference and current-mode stability. |
| Negative-to-Positive Converter | Automotive Battery Upconverter |
Use Scenario: Converting –12V vehicle chassis rail to +5V for microcontroller logic in CAN gateway modules. IC Role / Device Role / Timing Role: Inverting topology controller with VSW driving coupled inductor secondary winding. Use Value: Achieves ±1% output accuracy using 0.1% feedback resistors and avoids need for isolated DC-DC modules. | Use Scenario: Upconverting 9–16V automotive battery to stable 24V for ADAS camera power in start-stop vehicles. IC Role / Device Role / Timing Role: High-input-voltage boost controller with UVLO hysteresis and thermal protection for under-hood environments. Use Value: Operates reliably across full 3.5–30V input range and withstands load dump transients due to 60V switch breakdown rating. |
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 (external FETs); supports 4–36V input; no integrated switch. | Requires external power stage but offers higher efficiency (>95%) and bidirectional voltage regulation capability. | Select when efficiency >94% and input/output crossover (VIN ≈ VOUT) are required; not drop-in for LT1268CQ#TRPBF's integrated switch topology. |
| LM5118MH/NOPB | 100kHz–1MHz adjustable-frequency controller; 5.5–100V input; external N-channel FET drive; no integrated switch. | Supports wider input range and higher switching frequencies for smaller magnetics, but adds gate driver and FET BOM complexity. | Choose for high-input-voltage (>30V) or high-frequency (>150kHz) designs where thermal management of external FETs is feasible. |
Compared with LTC3789EFE#TRPBF and LM5118MH/NOPB, the LT1268CQ#TRPBF provides lowest system-level component count and fastest time-to-function for 7.5A, 150kHz boost/buck applications below 30V input - at the trade-off of fixed frequency and no synchronous rectification.
Availability
LT1268CQ#TRPBF is available at Aetrix Electronics and suitable for battery upconverters, industrial PC power supplies, negative-to-positive converters, and automotive DC-DC modules requiring stable component supply and long-term obsolescence support.
Supply support for LT1268CQ#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 full technical and manufacturing continuity for legacy Linear power products.
The LT1268 series belongs to Linear's monolithic high-power switching regulator product line, engineered for simplicity and ruggedness in demanding industrial and portable power applications where minimal external components and self-protection are essential.
FAQ
What is the maximum continuous output current achievable with the LT1268CQ#TRPBF in a standard 2-layer PCB layout?
The LT1268CQ#TRPBF's maximum continuous output current depends on thermal design. With a 2-layer board (1oz copper, ~20 cm² top copper area), θJA ≈ 40°C/W. At 7.5A switch current and 0.18Ω RDS(on), power dissipation reaches ~1.0A²×0.18Ω = 0.95W - yielding ~38°C rise above ambient. Thus, 5–6A continuous output is achievable with proper heatsinking and airflow, staying within 125°C TJ limit. Always verify with actual thermal imaging in final layout.
Does the LT1268CQ#TRPBF support synchronous rectification?
No, the LT1268CQ#TRPBF does not support synchronous rectification. It integrates a single N-channel MOSFET high-side switch and requires an external Schottky diode (e.g., MBR1035) in boost and flyback configurations. Its architecture is optimized for simplicity and cost-sensitive designs rather than peak efficiency - unlike modern controllers such as the LTC3789EFE#TRPBF which drive external synchronous FETs.
Can the LT1268CQ#TRPBF be used in a buck-boost (4-switch) configuration?
No, the LT1268CQ#TRPBF cannot implement true 4-switch buck-boost. It supports only single-switch topologies: buck, boost, flyback, and inverting. Its pinout and internal architecture lack the dual-gate-drive capability and complementary timing needed for 4-switch operation. For buck-boost functionality, use the LT1268CQ#TRPBF in inverting configuration to generate negative outputs, or pair it with a second regulator for SEPIC-like behavior - but not as a native 4-switch controller.
What is the purpose of the VC pin on the LT1268CQ#TRPBF, and how is it used in shutdown mode?
The VC pin on the LT1268CQ#TRPBF serves dual functions: it sets peak inductor current via transconductance (12 A/V) and enables external synchronization or shutdown. In shutdown mode, pulling VC ≤150mV disables the internal switch and reduces total supply current to 100µA typical. This low-threshold, voltage-controlled shutdown allows clean, noise-immune power sequencing - critical in multi-rail systems where the LT1268CQ#TRPBF must enter ultra-low-power state without affecting upstream supplies.
How does the LT1268CQ#TRPBF's reference voltage tolerance affect output accuracy in a 5.3V boost design?
The LT1268CQ#TRPBF (LT1268B grade) has a reference voltage tolerance of ±9mV (±0.7%), enabling ±1% output accuracy when paired with 0.1% feedback resistors. In a 5.3V boost design using R1=4.043kΩ and R2=1.24kΩ, this tolerance directly contributes to output deviation. To maintain accuracy under load, Linear recommends routing load current through the case (not GND pin) and separating FB ground return - otherwise, ground bounce can introduce additional error beyond the LT1268CQ#TRPBF's specified limits.
LT1268CQ#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
LT1268CQ#TRPBF FAQ
1.How can I place an order for LT1268CQ#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1268CQ#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 LT1268CQ#TRPBF reliable?
The price and inventory of LT1268CQ#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1268CQ#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1268CQ#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1268CQ#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1268CQ#TRPBF?
LT1268CQ#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1268CQ#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 LT1268CQ#TRPBF?
For technical support, including LT1268CQ#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1268CQ#TRPBF requirements.
6.How does Aetrix verify that LT1268CQ#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1268CQ#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 LT1268CQ#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1268CQ#TRPBF?
All LT1268CQ#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1268CQ#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 LT1268CQ#TRPBF part is unused and in its original packaging.
Return procedure for LT1268CQ#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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