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Analog Devices Inc. LTC3605AEUF#PBF
- Part No.:
- LTC3605AEUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3605AEUF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:970
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Product details
Overview
LTC3605AEUF#PBF from Analog Devices (formerly Linear Technology) is a 20V, 5A synchronous step-down DC/DC regulator with constant-frequency current-mode control, integrated 70mΩ top and 35mΩ bottom N-channel MOSFETs, 4V–20V input range, and programmable 800kHz–4MHz switching frequency. It delivers high efficiency up to 96% in point-of-load power supplies for industrial embedded systems.
For engineers reviewing the LTC3605AEUF#PBF datasheet, LTC3605AEUF#PBF pinout, LTC3605AEUF#PBF application, or LTC3605AEUF#PBF equivalent, key selection criteria include its PolyPhase® capability (up to 12 phases), ±1% 0.6V reference accuracy, internal 3.3V INTVCC regulator, VIN overvoltage lockout at 23.5V, and phase-selectable CLKOUT for synchronized multi-regulator designs.
Technical Context
The LTC3605AEUF#PBF implements a dual-phase-locked loop architecture: one PLL synchronizes the internal oscillator to an external CLKIN (±30% range), while a second servo-loop locks 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 pin serving as both error amplifier output and compensation node.
It supports three operational modes via MODE pin: continuous conduction (CCM) when tied to INTVCC, discontinuous conduction (DCM) when grounded, and automatic transition between them. The TRACK/SS pin enables precise output voltage ramping and external voltage tracking, while VON pin allows VOUT-proportional on-time adjustment to stabilize switching frequency across output voltages.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5A continuous - supports high-density POL loads without external current sharing |
| Input Voltage Range | 4V to 20V - compatible with dual/triple Li-ion battery stacks and 5V/12V intermediate rails |
| Switching Frequency | 800kHz to 4MHz - enables use of sub-1µH inductors and reduces output capacitor size |
| Feedback Reference | 0.6V ±1% - ensures tight output regulation across temperature and line/load conditions |
| Efficiency | Up to 96% at 1MHz - minimizes thermal stress and improves power density in compact layouts |
| Integrated MOSFETs | 70mΩ top / 35mΩ bottom - eliminates external switch losses and simplifies BOM |
| VIN Overvoltage Lockout | 23.5V trip / 21.5V release - protects internal FETs during transient surges without latch-off |
Pinout & Package
Package: 24-pin (4mm × 4mm) plastic QFN with exposed PGND pad (Pin 25), RoHS-compliant, –40°C to 125°C operating junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator programming | Resistor-to-SGND sets switching frequency; determines PLL lock window (±30%) |
| PHMODE (2) | Phase offset control | Selects 180° (2-phase), 120° (3-phase), or 90° (4-phase) CLKOUT relative to CLKIN |
| MODE (3) | Conduction mode select | INTVCC = forced CCM; SGND = DCM at light load; prevents shoot-through in low-IOUT |
| FB (4) | Feedback input | Compares resistive divider output to 0.6V reference; sets regulated VOUT |
| TRACK/SS (5) | Soft-start & tracking | 0–0.6V overrides reference for controlled ramp; >0.6V reverts to internal 0.6V |
| ITH (6) | Error amp output | Sets valley current threshold; tied to INTVCC enables internal compensation + voltage positioning |
| RUN (7) | Enable control | >1.2V enables full operation; <1.1V shuts down; draws <15µA in shutdown |
| PGOOD (8) | Power-good indicator | Open-drain output pulled low if VFB outside 0.54V–0.66V (±10%); includes 52-cycle blanking |
| VON (9) | On-time voltage input | Adjusts on-time proportional to VOUT; stabilizes fSW across output voltage changes |
| PGND (10, 25) | Power ground | Return path for internal FETs; exposed pad must be soldered to PCB ground for thermal & electrical performance |
| SW (11–16) | Switch node | Connects to inductor; swings from ~–0.3V to PVIN; requires low-inductance layout |
| PVIN (17, 18) | Main power input | Supplies gate drivers and power FETs; absolute max 22V |
| SVIN (19) | Signal input filter | Filtered version of PVIN for INTVCC LDO; bypassed with 0.1µF ceramic via 1–10Ω resistor |
| BOOST (20) | Bootstrap supply | Floating supply for top FET gate driver; connected to bootstrap capacitor (+) terminal |
| INTVCC (21) | Internal 3.3V rail | Powers control logic and drivers; requires ≥1µF low-ESR ceramic bypass to PGND |
| SGND (22) | Signal ground | Analog reference for FB, ITH, RUN, etc.; separate from PGND to minimize noise coupling |
| CLKOUT (23) | Phase-locked clock output | Drives CLKIN of next stage in PolyPhase® chain; amplitude = INTVCC to GND |
| CLKIN (24) | External sync input | Accepts external clock (800kHz–4MHz); internal 20kΩ pull-down to SGND |
Key Features
| Feature | Design Value |
|---|---|
| PolyPhase® operation | Supports up to 12 synchronized regulators via daisy-chained CLKIN/CLKOUT with user-selectable phase offsets |
| Constant-frequency current-mode control | Delivers fast transient response and stable operation across wide VIN/VOUT ratios without slope compensation |
| Integrated power MOSFETs | Eliminates external high-side/low-side switches and associated gate drive complexity |
| Output voltage tracking | Enables precise sequencing with other rails using external voltage source on TRACK/SS pin |
| VIN overvoltage protection | Auto-suspends switching at 23.5V and resumes at 21.5V-no latch-up or manual reset required |
| Internal 3.3V INTVCC regulator | Provides dedicated bias for gate drivers and analog circuitry; rated for 100mA RMS load |
Applications
| Point-of-Load Power Supply | Portable Instrumentation |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/3.3V/5V rails to FPGA, ASIC, or DSP cores on dense PCBs with strict thermal constraints. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering up to 5A with minimal external components and high PSRR. Use Value: High efficiency (96%) and 4MHz capability reduce inductor size and thermal footprint, enabling compact, fanless designs. | Use Scenario: Powering handheld test equipment (e.g., multimeters, spectrum analyzers) powered by 2–4 Li-ion cells (8–16V nominal). IC Role / Device Role / Timing Role: Main system regulator converting variable battery voltage to stable 3.3V for microcontroller and analog front-end. Use Value: 4V–20V input range accommodates full battery discharge curve; shutdown current <15µA extends runtime in sleep mode. |
| Distributed Power Systems | Battery-Powered Equipment |
Use Scenario: Multi-rail power architecture in telecom base stations or industrial controllers where multiple LTC3605AEUF#PBF units operate in PolyPhase® configuration. IC Role / Device Role / Timing Role: Synchronized buck stage in cascaded topology, sharing CLKIN/CLKOUT to minimize input/output ripple and EMI. Use Value: Phase alignment reduces input capacitor RMS current by up to 70%, allowing smaller bulk capacitance and lower cost. | Use Scenario: Power management in ruggedized field devices (e.g., portable data loggers, environmental sensors) requiring reliable operation from –40°C to 125°C. IC Role / Device Role / Timing Role: Primary DC/DC converter with robust thermal design, overvoltage protection, and precise output tracking for analog signal chains. Use Value: Guaranteed –40°C to 125°C operation, 0.6V ±1% reference, and 22V absolute max VIN ensure reliability in harsh environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3605EUF#PBF | Same pinout and function, but rated only for 0°C to 85°C junction temperature; 15V absolute max VIN vs. 22V | Suitable for commercial-grade applications without extended temperature or high-VIN transients | Select LTC3605EUF#PBF only if ambient temperature stays within 0°C–85°C and VIN never exceeds 15V |
| MP2451DT-LF-Z | 3A output, 4.5V–28V input, fixed 2MHz fSW, no PolyPhase®, no TRACK/SS or PHMODE pins | Lower-cost solution for non-synchronized, single-rail, moderate-current applications | Choose MP2451DT-LF-Z when phase synchronization, soft-start control, or >3A output are not required |
Compared with LTC3605EUF#PBF, the LTC3605AEUF#PBF adds extended temperature support and higher VIN tolerance; compared with MP2451DT-LF-Z, it provides higher current, programmable frequency, PolyPhase® capability, and precision tracking-making it suitable for demanding industrial and multi-rail designs.
Availability
LTC3605AEUF#PBF is available at Aetrix Electronics and suitable for point-of-load power supplies, portable instrumentation, distributed power systems, and battery-powered equipment requiring stable component supply across industrial temperature ranges.
Supply support for LTC3605AEUF#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. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LTC3605A product line was designed specifically for high-efficiency, high-current, multi-phase synchronous buck conversion in space-constrained industrial and communications infrastructure applications.
FAQ
What is the maximum input voltage rating for the LTC3605AEUF#PBF?
The LTC3605AEUF#PBF has an absolute maximum PVIN rating of 22V and includes VIN overvoltage lockout that activates at 23.5V (with 21.5V release threshold). This protects internal MOSFETs during transient spikes while maintaining compatibility with 20V-rated input rails and quad-Li-ion battery packs.
Does the LTC3605AEUF#PBF support external synchronization, and what is its lock range?
Yes, the LTC3605AEUF#PBF supports external synchronization via the CLKIN pin. Its internal PLL locks to external clocks in the 800kHz–4MHz range, with a synchronization window of ±30% around the RT-programmed frequency. For example, if RT sets 1MHz, CLKIN must be between 700kHz and 1.3MHz for reliable lock.
How does the TRACK/SS pin function during startup and tracking modes in the LTC3605AEUF#PBF?
During startup, applying a ramp voltage (0V → 0.6V) to the TRACK/SS pin forces the LTC3605AEUF#PBF to regulate VFB to that voltage, enabling controlled soft-start. Above 0.6V, tracking disables and regulation reverts to the internal 0.6V reference. For tracking, an external voltage source drives TRACK/SS to coordinate VOUT ramping with other rails.
Can the LTC3605AEUF#PBF operate in discontinuous conduction mode (DCM), and how is it enabled?
Yes, the LTC3605AEUF#PBF supports DCM at light loads. Tie the MODE pin to SGND to enable automatic DCM operation; tie MODE to INTVCC to force continuous conduction mode (CCM) regardless of load. DCM reduces light-load quiescent current and improves efficiency below ~0.5A.
What thermal considerations apply to the exposed pad (Pin 25) of the LTC3605AEUF#PBF?
The exposed pad (Pin 25) of the LTC3605AEUF#PBF is electrically and thermally connected to PGND. It must be soldered to a minimum 100mm² copper pour on the PCB for effective heat dissipation. Thermal resistance θJA is specified at 37°C/W with proper pad connection; insufficient soldering or undersized copper increases junction temperature and risks thermal shutdown.
LTC3605AEUF#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)
LTC3605AEUF#PBF FAQ
1.How can I place an order for LTC3605AEUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3605AEUF#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 LTC3605AEUF#PBF reliable?
The price and inventory of LTC3605AEUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3605AEUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3605AEUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3605AEUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3605AEUF#PBF?
LTC3605AEUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3605AEUF#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 LTC3605AEUF#PBF?
For technical support, including LTC3605AEUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3605AEUF#PBF requirements.
6.How does Aetrix verify that LTC3605AEUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3605AEUF#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 LTC3605AEUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3605AEUF#PBF?
All LTC3605AEUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3605AEUF#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 LTC3605AEUF#PBF part is unused and in its original packaging.
Return procedure for LTC3605AEUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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