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Analog Devices Inc. LTC3605AIUF#PBF
- Part No.:
- LTC3605AIUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3605AIUF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,131
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Product details
Overview
LTC3605AIUF#PBF from Analog Devices (formerly Linear Technology) is a 20V, 5A monolithic synchronous step-down regulator with phase-lockable controlled-on-time current-mode architecture. It operates from 4V to 20V input, delivers adjustable output down to 0.6V, supports 800kHz–4MHz switching frequency, and integrates 70mΩ/35mΩ N-channel MOSFETs for high-efficiency point-of-load conversion in battery-powered and distributed power systems.
For engineers reviewing the LTC3605AIUF#PBF datasheet, LTC3605AIUF#PBF pinout, LTC3605AIUF#PBF application, or LTC3605AIUF#PBF equivalent, key selection considerations include its ±1% 0.6V reference accuracy, PolyPhase® capability up to 12 phases, 125°C junction-rated operation, integrated INTVCC LDO, and VIN overvoltage lockout at 23.5V.
Technical Context
The LTC3605AIUF#PBF implements dual phase-locked loops: one synchronizes the internal oscillator to an external CLKIN signal (±30% range), while the other servos the on-time to maintain constant frequency under load and input variation. Its current-mode control uses valley-current sensing via the bottom FET's RDS(ON), with ITH voltage directly setting the current comparator threshold.
Operation supports both continuous (MODE = INTVCC) and discontinuous (MODE = SGND) modes. The TRACK/SS pin enables precise output voltage ramping and multi-rail tracking, while VON pin adjustment maintains constant switching frequency across varying output voltages - critical for noise-sensitive applications requiring stable clock alignment.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 20V - supports dual/triple Li-ion battery stacks and 5V/12V intermediate rails. |
| Output Current | 5A continuous - sufficient for FPGA core, ASIC, or high-performance processor rails. |
| Feedback Reference | 0.6V ±1% - enables accurate output programming from 0.6V to >5V using resistive divider. |
| Switching Frequency | 800kHz to 4MHz - programmable via RT resistor; allows small inductors (e.g., 1µH) and low-profile designs. |
| Efficiency | Up to 96% at 1MHz - achieved via integrated 70mΩ top / 35mΩ bottom MOSFETs and optimized gate drive. |
| Junction Temp Range | –40°C to +125°C - qualified for industrial and automotive under-hood environments. |
| VIN OV Lockout | 23.5V trip, 21.5V release - protects internal MOSFETs during transient overvoltage events without soft-start restart. |
Pinout & Package
Package: 24-pin (4mm × 4mm) QFN with exposed PGND pad (Pin 25), RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator frequency programming | Resistor-to-SGND sets fSW; 162k yields ~1MHz; ±30% sync window for CLKIN locking. |
| PHMODE (2) | PolyPhase phase offset control | INTVCC = 2-phase, SGND = 3-phase, INTVCC/2 = 4-phase - enables up to 12-phase cascading. |
| FB (4) | Output voltage feedback sense | Compares divider output to 0.6V reference; ±1% accuracy ensures tight regulation tolerance. |
| TRACK/SS (5) | Soft-start and voltage tracking input | Internal 2.5µA pull-up enables capacitor-based soft-start; external voltage enables rail sequencing. |
| ITH (6) | Error amplifier output & compensation node | Directly controls valley current limit; tie to INTVCC for internal compensation and voltage positioning. |
| RUN (7) | Enable/disable control | ≥1.2V enables full operation; ≤1.1V shuts down; draws <15µA in shutdown. |
| PGOOD (8) | Open-drain power-good indicator | Pulled low when FB exits ±10% of 0.6V (i.e., 0.54V–0.66V); includes 52-cycle blanking to suppress transients. |
| VON (9) | On-time voltage reference | Tie to VOUT to maintain constant fSW across output voltage changes; invalid if <0.6V or >6V. |
| PGND (10, 25) | Power ground return path | Must be soldered to PCB thermal pad for electrical continuity and θJA = 37°C/W thermal performance. |
| SW (11–16) | Switch node connection | Drives external inductor; swings from diode-drop below GND to PVIN; requires low-inductance layout. |
| PVIN (17, 18) | Main power input supply | Connects to bulk input capacitor; handles full input current and high dI/dt switching transients. |
| SVIN (19) | Filtered signal input for INTVCC LDO | Requires RC filter (1–10Ω + 0.1µF) from PVIN to reduce noise coupling into internal 3.3V regulator. |
| BOOST (20) | Top FET gate driver bootstrap supply | Swings from ~0.7V below INTVCC to PVIN + INTVCC; requires 0.1µF ceramic bootstrap capacitor. |
| INTVCC (21) | Internal 3.3V LDO output | Powers gate drivers and control logic; bypass with ≥1µF low-ESR ceramic; max 100mA RMS load. |
| CLKOUT (23) | PolyPhase synchronization output | INTVCC-to-GND square wave; phase relative to CLKIN set by PHMODE; drives next stage's CLKIN. |
| CLKIN (24) | External clock synchronization input | Internally terminated to SGND with 20kΩ; locks internal oscillator within ±30% of incoming frequency. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Delivers fast line/load transient response without slope compensation; ideal for high step-down ratios at high fSW. |
| PolyPhase® operation support | Enables up to 12 interleaved phases using CLKIN/CLKOUT chaining and PHMODE-selectable phase offsets. |
| Integrated power MOSFETs | Eliminates external high-side/low-side switches; reduces BOM count and layout complexity for compact PoL designs. |
| Output voltage tracking & soft-start | TRACK/SS pin supports precise rail sequencing (e.g., core before I/O) and inrush current limiting via external capacitor. |
| VIN overvoltage protection | Automatic suspension at 23.5V with immediate resumption at 21.5V - no latch-up or manual reset required. |
Applications
| Point-of-Load Regulation | Battery-Powered Instruments |
|---|---|
|
Use Scenario: Powering FPGA core voltage (e.g., 0.85V @ 4A) from a 12V intermediate rail in a portable test instrument. IC Role / Device Role / Timing Role: Primary DC/DC converter delivering tightly regulated, low-noise core supply with fast transient response to dynamic logic loads. Use Value: Achieves 95% efficiency at 1MHz, minimizing heat buildup in sealed enclosures while supporting PolyPhase® scaling for future higher-current variants. |
Use Scenario: Supplying 3.3V to microcontroller, sensors, and RF transceiver in handheld medical diagnostic equipment powered by dual Li-ion cells (8–8.4V). IC Role / Device Role / Timing Role: Main system regulator managing wide-input-range battery discharge while maintaining PGOOD signaling for safe shutdown. Use Value: 4V–20V input range accommodates full battery voltage swing; ±1% reference ensures sensor ADC accuracy; <15µA shutdown current extends battery life. |
| Distributed Power Systems | Industrial Control Modules |
|
Use Scenario: Cascading four LTC3605AIUF#PBF units in 4-phase configuration to deliver 20A at 1.2V to an AI inference accelerator board. IC Role / Device Role / Timing Role: Interleaved phase controller synchronized via CLKIN/CLKOUT with 90° offset per stage to minimize input/output ripple. Use Value: Reduces input capacitance requirement by ~75% vs. single-phase; spreads thermal load across multiple ICs; maintains tight regulation under 10A/µs load steps. |
Use Scenario: Providing isolated 5V and 3.3V rails in a DIN-rail mounted PLC I/O module operating in –40°C to +85°C ambient. IC Role / Device Role / Timing Role: Robust primary regulator handling 24V DC field supply with built-in OV protection and 125°C rated operation. Use Value: Withstands industrial voltage transients (e.g., ISO 7637-2 Pulse 1/2a); guaranteed specs over full temperature range eliminate derating concerns. |
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 | 3.5A max output, 4.5–28V input, fixed 500kHz fSW, no PolyPhase®, no TRACK/SS | Limited to lower-current, non-sequencing applications; lacks phase synchronization and precision soft-start | Select when cost sensitivity outweighs need for 5A rating, multi-phase scalability, or rail tracking. |
| TPS54560QDGQRQ1 | 5A, 3.5–60V input, adjustable fSW (100kHz–2.5MHz), integrated compensation, no CLKIN/CLKOUT | Wider input range suits 24V/48V industrial buses but lacks PolyPhase® coordination for multi-rail systems | Prefer for high-VIN automotive or industrial supplies where phase synchronization is unnecessary. |
Compared with MP2451DT-LF-Z and TPS54560QDGQRQ1, the LTC3605AIUF#PBF uniquely combines 5A capability, ±30% external clock sync, programmable phase offset, and precision tracking - making it optimal for high-density, multi-rail, noise-critical embedded systems demanding coordinated power delivery.
Availability
LTC3605AIUF#PBF is available at Aetrix Electronics and suitable for point-of-load regulation, battery-powered instrumentation, distributed power systems, industrial control modules, and PolyPhase® scalable power architectures requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LTC3605AIUF#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, communications, and aerospace markets.
The LTC3605AIUF#PBF belongs to Linear's high-efficiency monolithic buck regulator product line, designed specifically for demanding point-of-load applications requiring fast transient response, multi-phase scalability, and robust operation across wide input ranges and extreme temperatures.
FAQ
What is the absolute maximum input voltage rating for the LTC3605AIUF#PBF?
The LTC3605AIUF#PBF has an absolute maximum PVIN/SVIN voltage rating of 22V, with overvoltage lockout triggered at 23.5V and released at 21.5V. This protects the integrated 70mΩ/35mΩ MOSFETs during transient surges while allowing operation up to 20V continuous input - distinguishing it from the earlier LTC3605 (15V max).
How does the LTC3605AIUF#PBF achieve phase synchronization across multiple units?
The LTC3605AIUF#PBF achieves phase synchronization using two dedicated pins: CLKIN accepts an external clock (±30% of RT-set frequency), and CLKOUT outputs a synchronized square wave. By connecting CLKOUT of one LTC3605AIUF#PBF to CLKIN of the next, and configuring PHMODE pins to INTVCC/SGND/INTVCC/2, users implement 2/3/4-phase interleaving - scalable to 12 phases.
Can the LTC3605AIUF#PBF operate in discontinuous conduction mode (DCM)?
Yes, the LTC3605AIUF#PBF supports DCM at light loads when the MODE pin is tied to SGND. In this mode, the bottom MOSFET turns off when inductor current reaches zero, reducing switching losses. Tying MODE to INTVCC forces continuous conduction mode (CCM) regardless of load - essential for low-noise, constant-frequency operation.
What is the purpose of the SVIN pin on the LTC3605AIUF#PBF, and how should it be connected?
The SVIN pin supplies the internal 3.3V INTVCC LDO with a filtered version of PVIN. It must be connected to PVIN through a 1Ω–10Ω resistor and bypassed to PGND with a 0.1µF ceramic capacitor. This filtering prevents noise from the high-dI/dt PVIN node from degrading INTVCC regulation and gate driver performance.
Does the LTC3605AIUF#PBF require external compensation components on the ITH pin?
No - the LTC3605AIUF#PBF supports both configurations. Leaving ITH open enables external OPTI-LOOP® compensation for optimized transient response. Alternatively, tying ITH to INTVCC activates internal compensation (30kΩ + 40pF), simplifying design at the trade-off of fixed voltage positioning (±1.5% load regulation).
LTC3605AIUF#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):
- 20V
- Voltage - Output (Min/Fixed):
- 0.6V
- Voltage - Output (Max):
- 19.8V
- 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)
LTC3605AIUF#PBF FAQ
1.How can I place an order for LTC3605AIUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3605AIUF#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 LTC3605AIUF#PBF reliable?
The price and inventory of LTC3605AIUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3605AIUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3605AIUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3605AIUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3605AIUF#PBF?
LTC3605AIUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3605AIUF#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 LTC3605AIUF#PBF?
For technical support, including LTC3605AIUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3605AIUF#PBF requirements.
6.How does Aetrix verify that LTC3605AIUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3605AIUF#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 LTC3605AIUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3605AIUF#PBF?
All LTC3605AIUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3605AIUF#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 LTC3605AIUF#PBF part is unused and in its original packaging.
Return procedure for LTC3605AIUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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