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Analog Devices Inc. LTC3605EUF#PBF
- Part No.:
- LTC3605EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3605EUF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:5,196
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Product details
Overview
LTC3605EUF#PBF from Analog Devices (formerly Linear Technology) is a monolithic synchronous step-down DC/DC regulator delivering up to 5A output current with programmable switching frequency from 800kHz to 4MHz, integrated 70mΩ top and 35mΩ bottom N-channel MOSFETs, and 0.6V ±1% reference accuracy - designed for point-of-load power in dual Li-ion battery systems and 5V/12V rail applications.
For engineers reviewing the LTC3605EUF#PBF datasheet, LTC3605EUF#PBF pinout, LTC3605EUF#PBF application, or LTC3605EUF#PBF equivalent, key selection considerations include its constant-frequency current-mode architecture, PolyPhase® capability for multi-phase scaling, internal 3.3V INTVCC regulator, phase-selectable CLKOUT, and support for output tracking and soft-start via TRACK/SS pin.
Technical Context
The LTC3605EUF#PBF implements a phase-lockable controlled-on-time current-mode architecture with two internal PLLs: one synchronizes the oscillator to an external CLKIN (±30% range), while the other servos the on-time to maintain constant frequency under varying input/output conditions. It supports discontinuous mode (via MODE pin) or forced continuous conduction mode.
Its control loop uses valley-current sensing through the bottom MOSFET's RDS(ON), with ITH pin serving as both error amplifier output and compensation node. The device integrates overvoltage (±10% PGOOD window), undervoltage, thermal shutdown, and VIN overvoltage protection (17V trip, 15V recovery), and features programmable minimum on-time (40ns) and off-time (70ns) constraints.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 15V - supports dual Li-ion batteries (8.4V max) and standard 5V/12V intermediate rails. |
| Output Current | 5A continuous - enables single-chip PoL conversion for FPGA, ASIC, or DSP core supplies. |
| Switching Frequency | 800kHz–4MHz (RT-programmable) - allows use of sub-1µH inductors and minimizes EMI filter size. |
| Reference Voltage | 0.6V ±1% (–40°C to 85°C) - ensures tight output regulation across industrial temperature range. |
| Efficiency | Up to 96% at 12VIN/3.3VOUT/1MHz - reduces thermal load and improves power density in compact layouts. |
| MOSFET RDS(ON) | 70mΩ (top), 35mΩ (bottom) - lowers conduction loss and simplifies thermal design vs discrete solutions. |
| Shutdown Current | <15µA - meets ultra-low quiescent requirements for battery-backed systems. |
Pinout & Package
Package: 24-pin (4mm × 4mm) plastic QFN with exposed PGND pad (Pin 25), rated for –40°C to 85°C operation.
| 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 selection control | Configures CLKOUT phase offset (180°/120°/90°) for 2-/3-/4-phase PolyPhase® operation. |
| MODE (3) | Operation mode select | Tie to INTVCC for forced CCM; tie to SGND for 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 | Drives ramp-up of VOUT; internal 2µA pull-up enables capacitor-based soft-start or external voltage tracking. |
| ITH (6) | Error amplifier output / compensation | Sets valley current threshold; tie to INTVCC for simplified internal compensation and output voltage positioning. |
| RUN (7) | Enable/disable control | Logic-high (>1.2V) enables regulation; <1.1V forces shutdown with <15µA IQ. |
| PGOOD (8) | Power-good open-drain output | Asserts high when VFB is within ±10% of 0.6V; includes 52-cycle blanking to suppress transient glitches. |
| VON (9) | On-time voltage input | Adjusts on-time proportionally to VOUT; maintains constant fSW across output voltages when tied to VOUT. |
| PGND (10, 25) | Power ground return | Return path for internal MOSFETs; exposed pad must be soldered to PCB ground for thermal and electrical performance. |
| SW (11–16) | Switch node connection | Connects to external inductor; swings from ~–0.3V to PVIN; requires low-inductance layout for EMI control. |
| PVIN (17, 18) | Main power input | Supplies gate drivers and power MOSFETs; accepts 4V–15V with overvoltage lockout at 17V. |
| SVIN (19) | Filtered signal input | Provides clean bias to internal 3.3V LDO; requires RC filter (1Ω–10Ω + 0.1µF) from PVIN to reduce noise coupling. |
| BOOST (20) | Top MOSFET gate drive supply | Bootstrap node for high-side driver; swings from ~INTVCC–0.3V to PVIN+INTVCC; requires 0.1µF ceramic bootstrap cap. |
| INTVCC (21) | Internal 3.3V regulator output | Powers control circuitry and gate drivers; requires ≥1µF low-ESR ceramic bypass to PGND. |
| SGND (22) | Signal ground reference | Reference for analog circuitry; separate from PGND to minimize noise coupling into feedback path. |
| CLKOUT (23) | PolyPhase® clock output | Phase-adjustable clock for cascading regulators; amplitude = INTVCC to GND; drives next stage's CLKIN. |
| CLKIN (24) | External synchronization input | Accepts 0.7V logic threshold clock; internal 20kΩ pull-down enables single-wire sync without external bias. |
Key Features
| Feature | Design Value |
|---|---|
| Constant-frequency current-mode control | Delivers fast line/load transient response while maintaining stable switching frequency across input/output variations. |
| PolyPhase® operation (up to 12 phases) | Enables scalable high-current outputs (e.g., 60A with 12× LTC3605EUF#PBF) using minimal input/output capacitance and interleaved ripple cancellation. |
| Integrated 70mΩ/35mΩ MOSFETs | Eliminates external power switches and associated gate drive complexity, reducing BOM count and PCB area by >30% vs discrete controllers. |
| 0.6V ±1% reference with tracking/soft-start | Supports precise multi-rail sequencing and inrush current limiting in systems with multiple regulated supplies. |
| Programmable frequency (800kHz–4MHz) | Allows optimization for size (high-f), efficiency (mid-f), or EMI (low-f with spread-spectrum sync), all within one footprint. |
Applications
| Point-of-Load Power Supply | Portable Instruments |
|---|---|
Use Scenario: Regulating 12V intermediate bus down to 1.2V/3.3V for FPGA core and I/O rails in compact test equipment. IC Role / Device Role / Timing Role: Primary synchronous buck controller providing tightly regulated, low-noise DC power with fast transient response. Use Value: Enables single-chip 5A solution with integrated MOSFETs, eliminating external power stages and reducing layout sensitivity to parasitic inductance. | Use Scenario: Powering handheld medical monitors with dual Li-ion battery input (6V–8.4V) and multiple output rails (1.8V, 3.3V, 5V). IC Role / Device Role / Timing Role: High-efficiency step-down regulator operating across full battery discharge curve while maintaining stable output during load transients. Use Value: 96% peak efficiency and <15µA shutdown current extend battery runtime; programmable frequency avoids sensitive RF bands. |
| Distributed Power Systems | Battery-Powered Equipment |
Use Scenario: Cascading four LTC3605EUF#PBF in 4-phase configuration to deliver 20A at 1.0V for AI edge inference module with strict thermal limits. IC Role / Device Role / Timing Role: Interleaved PolyPhase® regulator node synchronized via CLKIN/CLKOUT to minimize input/output ripple and thermal hotspots. Use Value: Reduces required input capacitance by 4× and output ripple by >75% vs single-phase, easing EMI filtering and thermal management. | Use Scenario: Supplying 3.3V to wireless sensor node MCU and RF transceiver from 5V USB or single Li-ion source. IC Role / Device Role / Timing Role: Compact, high-frequency buck converter enabling small inductor/capacitor selection and rapid load-step recovery. Use Value: 4MHz operation allows 0.47µH inductor and 22µF ceramic output cap - cutting solution size by >40% vs 500kHz alternatives. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MP2315DJ-LF-Z | 4.5V–24V input, 3A output, fixed 500kHz/1.5MHz fSW, no PolyPhase®, no TRACK/SS | Limited to lower current and fixed frequency; lacks output tracking and multi-phase sync capability | Choose MP2315DJ-LF-Z only for cost-sensitive, non-sequenced 3A applications where board space permits larger magnetics. |
| TPS54560QDGQRQ1 | 3.5V–60V input, 5A output, adjustable 100kHz–2.5MHz fSW, integrated compensation, no CLKOUT/PHMODE | Wider VIN range suits automotive 12V/24V systems but lacks PolyPhase® and precise 0.6V reference (0.8V typical) | Choose TPS54560QDGQRQ1 for harsh-environment 12V/24V inputs requiring AEC-Q100 qualification, not for multi-phase or precision-tracking designs. |
Compared with MP2315DJ-LF-Z and TPS54560QDGQRQ1, the LTC3605EUF#PBF uniquely combines 5A capability, 0.6V ±1% reference, PolyPhase® scalability, and TRACK/SS sequencing - making it the only option among the three qualified for high-density, multi-rail, and synchronized high-current PoL systems.
Availability
LTC3605EUF#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 industrial temperature ranges.
Supply support for LTC3605EUF#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 LTC3605EUF#PBF belongs to ADI's Power by Linear™ family of monolithic DC/DC regulators, engineered specifically for high-efficiency, high-density point-of-load conversion in space-constrained and thermally demanding applications.
FAQ
What is the maximum output current supported by the LTC3605EUF#PBF?
The LTC3605EUF#PBF delivers up to 5A continuous output current under typical thermal conditions (4mm × 4mm QFN with proper PCB copper pour). Its integrated 70mΩ top and 35mΩ bottom N-channel MOSFETs enable this rating without external switches. Derating is required above 85°C ambient or with insufficient heatsinking - refer to θJA = 37°C/W and maximum junction temperature of 125°C in the datasheet for thermal design.
Does the LTC3605EUF#PBF support external synchronization, and what is its frequency range?
Yes, the LTC3605EUF#PBF supports external synchronization via the CLKIN pin across 800kHz to 4MHz, with a ±30% lock range relative to the RT-programmed frequency. For example, if RT sets 1MHz, CLKIN must be between 700kHz and 1.3MHz to achieve lock. The device also provides a phase-controllable CLKOUT signal for cascading multiple LTC3605EUF#PBF units in PolyPhase® configurations.
How does the TRACK/SS pin function on the LTC3605EUF#PBF?
The TRACK/SS pin on the LTC3605EUF#PBF serves dual functions: when driven externally (0V–0.6V), it overrides the internal 0.6V reference to enable output voltage tracking; when left floating with an external capacitor, its internal 2µA pull-up current creates a linear voltage ramp, implementing soft-start. This eliminates inrush current and supports precise power-rail sequencing in multi-supply systems using the LTC3605EUF#PBF.
What is the purpose of the SVIN pin on the LTC3605EUF#PBF, and how should it be connected?
The SVIN pin on the LTC3605EUF#PBF supplies filtered input to the internal 3.3V LDO (INTVCC). It must be connected to PVIN through a low-pass RC network (1Ω–10Ω resistor + 0.1µF ceramic capacitor to PGND) to suppress high-frequency noise that could destabilize the INTVCC regulator. Direct connection to PVIN or omission of filtering risks increased output ripple and reduced light-load efficiency due to noise coupling into the control loop.
Can the LTC3605EUF#PBF operate in discontinuous conduction mode (DCM), and how is it enabled?
Yes, the LTC3605EUF#PBF supports DCM at light loads to improve efficiency. It is enabled by tying the MODE pin (Pin 3) to SGND. In DCM, the bottom MOSFET turns off when inductor current reaches zero, minimizing switching losses. For forced continuous conduction mode (CCM) across all loads - e.g., to avoid audible noise or ensure consistent loop behavior - tie MODE to INTVCC. Do not leave MODE floating.
LTC3605EUF#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 ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-QFN (4x4)
LTC3605EUF#PBF FAQ
1.How can I place an order for LTC3605EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3605EUF#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 LTC3605EUF#PBF reliable?
The price and inventory of LTC3605EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3605EUF#PBF is usually 5 days.
3.What payment methods are accepted for LTC3605EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3605EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3605EUF#PBF?
LTC3605EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3605EUF#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 LTC3605EUF#PBF?
For technical support, including LTC3605EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3605EUF#PBF requirements.
6.How does Aetrix verify that LTC3605EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3605EUF#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 LTC3605EUF#PBF meets industry standards.
7.What is the process for return or replacement of LTC3605EUF#PBF?
All LTC3605EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3605EUF#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 LTC3605EUF#PBF part is unused and in its original packaging.
Return procedure for LTC3605EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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