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Analog Devices Inc. LTC3605IUF#PBF
- Part No.:
- LTC3605IUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3605IUF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,953
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Product details
Overview
LTC3605IUF#PBF from Analog Devices (formerly Linear Technology) is a monolithic synchronous step-down DC/DC regulator delivering up to 5A output current with programmable 800kHz–4MHz switching frequency, integrated 70mΩ top / 35mΩ bottom N-channel MOSFETs, and ±1% 0.6V reference accuracy-designed for point-of-load power in dual Li-ion battery systems and 12V/5V rail applications.
For engineers reviewing the LTC3605IUF#PBF datasheet, LTC3605IUF#PBF pinout, LTC3605IUF#PBF application, or LTC3605IUF#PBF equivalent, key selection considerations include its constant-frequency current-mode architecture, PolyPhase® capability for multi-phase scaling, external synchronization support, phase-selectable CLKOUT, and thermal-limited operation up to 125°C junction temperature.
Technical Context
The LTC3605IUF#PBF implements a controlled-on-time, constant-frequency current-mode control architecture with two internal PLLs: one synchronizing the oscillator to an external CLKIN (±30% range), and another servoing the on-time to lock to either internal or external clock. It supports discontinuous conduction mode (DCM) via MODE pin control and includes foldback current limiting during short-circuit conditions.
Its dual-VIN architecture separates PVIN (power path) from SVIN (signal bias path), enabling stable 3.3V INTVCC regulation across 4V–15V input while minimizing noise coupling. The ITH pin serves as both error amplifier output and compensation node, supporting internal (ITH tied to INTVCC) or external OPTI-LOOP® compensation for optimized transient response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5A continuous-supports high-density POL conversion without external MOSFETs. |
| Input Voltage Range | 4V to 15V-enables direct use with dual Li-ion batteries (8.4V max) or 12V/5V system rails. |
| Switching Frequency | 800kHz to 4MHz (resistor-programmable or externally synchronized)-enables compact magnetics and low-profile inductor selection. |
| Reference Voltage | 0.6V ±1% over –40°C to 125°C-ensures tight output regulation across industrial temperature range. |
| Efficiency | Up to 96% at 1MHz, 12VIN/3.3VOUT/5A-minimizes thermal load in space-constrained designs. |
| Integrated FETs | 70mΩ top / 35mΩ bottom N-MOSFETs-eliminates external power switches and reduces BOM count. |
| PolyPhase Support | Up to 12 phases via CLKIN/CLKOUT chaining and PHMODE-selectable phase offsets-enables scalable high-current solutions with reduced input/output ripple. |
Pinout & Package
Package: 24-pin (4mm × 4mm) plastic QFN with exposed PGND pad (Pin 25), rated for –40°C to 125°C operating temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator frequency programming | Resistor-to-SGND sets switching frequency; determines minimum off-time and duty cycle limits. |
| PHMODE (2) | Phase offset selector | Configures CLKOUT phase shift vs CLKIN: INTVCC = 180° (2-phase), SGND = 120° (3-phase), INTVCC/2 = 90° (4-phase). |
| MODE (3) | Operation mode control | Tied to INTVCC forces CCM; tied to SGND enables DCM at light loads to improve light-load efficiency. |
| FB (4) | Feedback voltage input | Compares resistive divider output against 0.6V reference to regulate VOUT. |
| TRACK/SS (5) | Tracking & soft-start control | 0–0.6V overrides reference for voltage tracking; capacitor enables controlled VOUT ramp-up. |
| ITH (6) | Error amplifier output & compensation | Sets valley current threshold; internal compensation enabled when tied to INTVCC. |
| RUN (7) | Enable/disable control | >1.2V enables full operation; <1.1V places device in shutdown (<15µA IQ). |
| PGOOD (8) | Power-good open-drain output | Pulled low when FB voltage deviates >±10% from 0.6V-provides system-level power sequencing feedback. |
| VON (9) | On-time voltage input | Adjusts on-time proportionally to VOUT; maintains constant fSW across output voltage changes. |
| PGND (10, 25) | Power ground return | High-current return path for internal MOSFETs; exposed pad must be soldered for thermal and electrical performance. |
| SW (11–16) | Switch node connection | Connects to inductor; swings from ~–0.3V to PVIN-requires low-inductance layout to minimize EMI. |
| PVIN (17, 18) | Main power input | Supplies gate drivers and power MOSFETs; accepts 4V–15V with transient rating to 17.5V. |
| SVIN (19) | Signal input for INTVCC LDO | Filtered PVIN input to 3.3V bias regulator; decoupling prevents noise injection into control circuitry. |
| BOOST (20) | Bootstrap supply for top FET | Drives high-side gate; requires external bootstrap capacitor between BOOST and SW. |
| INTVCC (21) | Internal 3.3V regulator output | Powers gate drivers and analog circuits; requires ≥1µF ceramic bypass to PGND. |
| SGND (22) | Signal ground reference | Reference for analog control circuitry; separate from PGND to avoid noise coupling. |
| CLKOUT (23) | PolyPhase clock output | Phase-aligned clock signal used to synchronize downstream LTC3605 regulators. |
| CLKIN (24) | External clock input | Accepts 800kHz–4MHz sync signal; internal PLL locks oscillator and on-time to rising edge. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Delivers fast line/load transient response while maintaining predictable EMI profile and stable loop behavior across wide VIN/VOUT ranges. |
| PolyPhase® operation with programmable phase offset | Enables up to 12-phase interleaving using only CLKIN/CLKOUT signals-reduces input/output ripple by √N and eases thermal management. |
| Integrated 70mΩ/35mΩ N-MOSFETs | Eliminates external power switches and associated gate drive complexity-reducing solution size and improving efficiency at 5A. |
| 0.6V ±1% reference over –40°C to 125°C | Ensures accurate output voltage regulation across full industrial temperature range without external trimming. |
| External synchronization with ±30% lock range | Allows deterministic noise placement in noise-sensitive systems (e.g., RF, audio, precision ADCs) without sacrificing regulation fidelity. |
| Output tracking and soft-start via TRACK/SS pin | Supports power sequencing in multi-rail systems and prevents inrush current during startup-critical for FPGA, ASIC, and processor supplies. |
Applications
| Point-of-Load Power Supply | Portable Instruments |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/3.3V/5V rails to FPGAs, microprocessors, or high-speed SerDes in compact embedded systems. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering up to 5A with fast transient response and precise voltage positioning. Use Value: Enables single-chip 5A POL conversion with minimal external components-reducing board area and simplifying thermal design. | Use Scenario: Powering handheld test equipment, portable data loggers, or battery-powered medical monitors requiring long runtime and stable output under varying load. IC Role / Device Role / Timing Role: High-efficiency step-down converter operating from dual Li-ion cells (8.4V max) with low quiescent current in shutdown mode. Use Value: Delivers >95% efficiency at 1MHz/5A and draws <15µA in shutdown-extending battery life while maintaining fast wake-up response. |
| Distributed Power Systems | Battery-Powered Equipment |
Use Scenario: Cascading multiple LTC3605IUF#PBF units in PolyPhase® configuration to deliver >20A at 1.8V for AI accelerators or server memory subsystems. IC Role / Device Role / Timing Role: Phase-synchronized buck controller with CLKIN/CLKOUT interface and PHMODE-selectable phase offsets. Use Value: Reduces input/output capacitance requirements by √12 and spreads thermal load across multiple ICs-improving power density and reliability. | Use Scenario: Regulating 3.3V or 5V outputs in ruggedized industrial handhelds, barcode scanners, or portable IoT gateways operating across wide ambient temperatures. IC Role / Device Role / Timing Role: Industrial-grade DC/DC converter qualified for –40°C to 125°C junction temperature with robust overvoltage and thermal protection. Use Value: Guarantees operation in harsh environments without derating-supported by guaranteed specs over full temperature range and 125°C TJMAX. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2451DT-LF-Z | 3A rated, 4.5V–28V input, fixed 500kHz fSW, no external sync or PolyPhase support | Suitable for lower-current, cost-sensitive applications without multi-phase or frequency flexibility needs | Select when 3A output suffices and external synchronization or phase control is unnecessary. |
| TPS54560QPWPRQ1 | 5A rated, 3.5V–60V input, adjustable 100kHz–2.5MHz fSW, sync capable, but no integrated phase-offset logic or TRACK/SS pin | Better for wide-input automotive or industrial systems where high VIN tolerance is critical | Choose when input exceeds 15V or AEC-Q100 qualification is required-LTC3605IUF#PBF lacks automotive qualification. |
Compared with MP2451DT-LF-Z and TPS54560QPWPRQ1, the LTC3605IUF#PBF uniquely combines 5A capability, PolyPhase® scalability, ±30% sync range, and precision 0.6V reference over full industrial temperature range-making it optimal for high-density, multi-rail, noise-sensitive POL designs where phase control and tracking are essential.
Availability
LTC3605IUF#PBF is available at Aetrix Electronics and suitable for point-of-load power supply, portable instrumentation, distributed power systems, and battery-powered equipment requiring stable component supply across extended temperature operation.
Supply support for LTC3605IUF#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC3605IUF#PBF belongs to ADI's Power by Linear™ family of high-efficiency monolithic DC/DC regulators, engineered specifically for demanding point-of-load applications requiring precision regulation, fast transient response, and scalable multi-phase operation in space- and thermally-constrained environments.
FAQ
What is the maximum junction temperature specification for the LTC3605IUF#PBF?
The LTC3605IUF#PBF has a maximum junction temperature (TJMAX) of 125°C, with guaranteed operation over the full –40°C to 125°C case temperature range. Thermal protection activates above this threshold, and the device's θJA is 37°C/W. Proper PCB layout-including soldering the exposed PGND pad-is required to achieve rated thermal performance. The LTC3605IUF#PBF must not operate continuously above 125°C to ensure long-term reliability.
Does the LTC3605IUF#PBF support external synchronization, and what is its lock range?
Yes, the LTC3605IUF#PBF supports external synchronization via the CLKIN pin, with a lock range of ±30% around the frequency set by the RT resistor. For example, if RT programs 1MHz, CLKIN must be between 700kHz and 1.3MHz for reliable lock. The internal PLL simultaneously synchronizes both the oscillator and the on-time generator, preserving constant-frequency operation even during sync transitions. This capability is fully supported in the LTC3605IUF#PBF across its –40°C to 125°C operating range.
How does the TRACK/SS pin function in the LTC3605IUF#PBF, and what design value does it provide?
The TRACK/SS pin on the LTC3605IUF#PBF enables output voltage tracking and soft-start. When driven from 0V to 0.6V, it overrides the internal 0.6V reference to servo FB to the applied TRACK voltage-enabling precise power sequencing in multi-rail systems. A capacitor on this pin provides controlled VOUT ramp-up, preventing input surge current. This functionality is integral to the LTC3605IUF#PBF's role in FPGA, processor, and ASIC power supplies where coordinated rail ramping is mandatory for reliable startup.
What are the key differences between the LTC3605IUF#PBF and the LTC3605EUF#PBF?
The LTC3605IUF#PBF is specified for operation from –40°C to 125°C junction temperature and is guaranteed over that full range, while the LTC3605EUF#PBF is only guaranteed from –40°C to 85°C. Electrical parameters such as reference voltage accuracy (±1%), current limit (±15%), and PGOOD thresholds are tested and assured across the wider temperature span for the LTC3605IUF#PBF. Both share identical pinout, package, and functional features-but the LTC3605IUF#PBF is intended for industrial and extended-temperature applications where sustained high-temperature operation is required.
Can the LTC3605IUF#PBF operate in discontinuous conduction mode (DCM), and how is it enabled?
Yes, the LTC3605IUF#PBF supports discontinuous conduction mode (DCM) at light loads to improve efficiency. DCM is enabled by tying the MODE pin (Pin 3) to SGND. In this state, the bottom MOSFET turns off when inductor current reaches zero, reducing switching losses. When MODE is tied to INTVCC, the device operates in forced continuous conduction mode (CCM) regardless of load. This mode selection is fully supported in the LTC3605IUF#PBF and is validated across its –40°C to 125°C operating range.
LTC3605IUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 15V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 14.85V
- Current - Output:
- 5A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3605IUF#PBF FAQ
1.How can I place an order for LTC3605IUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3605IUF#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 LTC3605IUF#PBF reliable?
The price and inventory of LTC3605IUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3605IUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3605IUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3605IUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3605IUF#PBF?
LTC3605IUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3605IUF#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 LTC3605IUF#PBF?
For technical support, including LTC3605IUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3605IUF#PBF requirements.
6.How does Aetrix verify that LTC3605IUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3605IUF#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 LTC3605IUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3605IUF#PBF?
All LTC3605IUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3605IUF#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 LTC3605IUF#PBF part is unused and in its original packaging.
Return procedure for LTC3605IUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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