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Analog Devices Inc. LTC3605AIUF#TRPBF
- Part No.:
- LTC3605AIUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LTC3605AIUF#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 24QFN
- Quantity:
- Payment:
- Shipping:
Inventory:543
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Product details
Overview
LTC3605AIUF#TRPBF from Analog Devices (formerly Linear Technology) is a 20V, 5A synchronous step-down DC/DC regulator with phase-lockable constant-frequency current-mode control, integrated 70mΩ top and 35mΩ bottom N-channel MOSFETs, 4V–20V input range, and 0.6V ±1% reference accuracy-used in point-of-load power supplies for industrial embedded systems and battery-powered instrumentation.
For engineers reviewing the LTC3605AIUF#TRPBF datasheet, LTC3605AIUF#TRPBF pinout, LTC3605AIUF#TRPBF application, or LTC3605AIUF#TRPBF equivalent, key selection criteria include its PolyPhase® capability (up to 12 phases), programmable 800kHz–4MHz switching frequency via RT resistor, external clock synchronization (CLKIN/CLKOUT), output tracking/soft-start (TRACK/SS), and 24-pin 4mm × 4mm QFN package with exposed PGND pad.
Technical Context
The LTC3605AIUF#TRPBF implements a dual-phase-locked-loop architecture: one PLL synchronizes the internal oscillator to an external CLKIN signal (±30% range), while a second PLL servos the on-time to maintain constant frequency under varying load and input conditions. It supports both continuous conduction mode (CCM) and discontinuous conduction mode (DCM), selectable via MODE pin.
Its current-mode control uses valley-current sensing through the bottom MOSFET's RDS(ON), with ITH pin serving as error amplifier output and compensation node. The device integrates an internal 3.3V LDO (INTVCC) powered from SVIN, with dedicated PVIN/SVIN separation for noise isolation and VIN overvoltage protection (23.5V trip, 21.5V release).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5A continuous - supports high-density PoL loads without external MOSFETs |
| Input Voltage Range | 4V to 20V - compatible with 2–4 Li-ion stacks and 5V/12V intermediate rails |
| Switching Frequency | 800kHz to 4MHz, programmable via RT resistor - enables compact magnetics and low-profile designs |
| Reference Voltage | 0.6V ±1% - ensures tight output regulation across temperature and line/load |
| Efficiency | Up to 96% at 1MHz, VOUT = 3.3V - minimizes thermal stress in enclosed environments |
| MOSFET RDS(ON) | 70mΩ (top), 35mΩ (bottom) - reduces conduction loss and improves light-load efficiency |
| PolyPhase Support | Up to 12 phases via CLKIN/CLKOUT and PHMODE pin - enables >60A scalable output 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 junction temperature. Exposed pad must be soldered to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RT (1) | Oscillator programming | Resistor-to-SGND sets switching frequency (800kHz–4MHz); determines PLL lock range |
| PHMODE (2) | Phase offset control | Selects 2-phase (INTVCC), 3-phase (SGND), or 4-phase (INTVCC/2) CLKOUT relative to CLKIN |
| MODE (3) | Conduction mode select | INTVCC = forced CCM; SGND = DCM at light load; prevents shoot-through and improves efficiency |
| FB (4) | Feedback input | Compares resistive divider voltage to 0.6V reference; sets output voltage per VOUT = 0.6V × (1 + R2/R1) |
| TRACK/SS (5) | Tracking & soft-start | 0–0.6V overrides reference for output ramp control; capacitor enables controlled startup and sequencing |
| ITH (6) | Error amp output & compensation | Sets valley current threshold; tied to INTVCC enables internal compensation and output voltage positioning |
| RUN (7) | Enable control | >1.2V enables operation; <1.1V disables regulators and reduces quiescent current to <15µA |
| PGOOD (8) | Power-good indicator | Open-drain output pulled low when FB exits ±10% of 0.6V (i.e., 0.54V–0.66V); includes 52-cycle blanking |
| VON (9) | On-time modulation | Tying to VOUT maintains constant frequency across output voltages; deviation <0.6V or >6V breaks constancy |
| PGND (10, 25) | Power ground return | Common return for internal MOSFETs; exposed pad (Pin 25) must be soldered to PCB ground plane |
| SW (11–16) | Switch node | Connects to inductor; swings from ~–0.3V to PVIN; multiple pins reduce trace inductance and improve thermal spreading |
| PVIN (17, 18) | Main power input | Supplies gate drivers and high-side MOSFET; separate from SVIN to isolate noise-sensitive bias circuitry |
| SVIN (19) | Signal input supply | Filtered input to internal 3.3V LDO (INTVCC); requires RC filter (1–10Ω + 0.1µF) to suppress PVIN transients |
| BOOST (20) | Bootstrap supply | Drives high-side gate; connects to bootstrap capacitor (+) terminal; swings up to PVIN + INTVCC |
| INTVCC (21) | Internal 3.3V supply | Powers control logic and gate drivers; requires ≥1µF ceramic bypass to PGND; max 100mA RMS load |
| SGND (22) | Signal ground | Reference for analog circuits (FB, ITH, TRACK/SS); separate from PGND to minimize noise coupling |
| CLKOUT (23) | Phase-locked clock output | Drives CLKIN of next stage; amplitude = INTVCC to GND; phase offset set by PHMODE |
| CLKIN (24) | External sync input | Accepts 800kHz–4MHz clock; internal 20kΩ pull-down; PLL locks switching edge to rising CLKIN |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Power MOSFETs | Eliminates external high-side/low-side switches; reduces BOM count and layout complexity |
| PolyPhase® Operation | Enables interleaved multi-phase operation up to 12 phases using only CLKIN/CLKOUT and PHMODE |
| Output Tracking & Soft-Start | Ensures controlled power-up sequencing across multiple rails; prevents inrush current and bus droop |
| VIN Overvoltage Protection | Automatically suspends switching at 23.5V PVIN and resumes at 21.5V-protects MOSFETs during transient spikes |
| Internal 3.3V LDO (INTVCC) | Provides regulated bias for gate drivers and control logic; eliminates need for external bias supply |
Applications
| Point-of-Load Power Supply | Portable Instrumentation |
|---|---|
Use Scenario: Providing tightly regulated 1.2V/3.3V/5V rails to FPGAs, ASICs, or DSPs on dense PCBs with limited board area. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering up to 5A with fast transient response and minimal output capacitance. Use Value: High efficiency (96%) and 1MHz+ operation allow small 1µH inductors and ceramic capacitors, reducing solution footprint by >40% vs. lower-frequency alternatives. | Use Scenario: Powering handheld test equipment (e.g., portable oscilloscopes, multimeters) operating from 2–4 Li-ion cells (8–16.8V nominal). IC Role / Device Role / Timing Role: Main system regulator converting variable battery voltage to stable 3.3V for microcontroller, ADC, and display subsystems. 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: Cascading multiple LTC3605AIUF#TRPBF units across a backplane to deliver >20A with low input ripple and thermal sharing. IC Role / Device Role / Timing Role: Interleaved PolyPhase® node synchronized via CLKIN/CLKOUT to achieve 12-phase operation. Use Value: Phase staggering reduces input capacitor RMS current by up to 70%, enabling smaller, lower-cost bulk capacitors and cooler operation. | Use Scenario: Power management in ruggedized field devices (e.g., wireless sensors, IoT edge nodes) requiring long service life and wide temperature operation. IC Role / Device Role / Timing Role: Primary DC/DC converter supporting –40°C to 125°C ambient with robust overvoltage, overtemperature, and current-limit protection. Use Value: Guaranteed spec compliance across full temperature range (I-grade), plus VIN OVP and PGOOD enable reliable fault detection in unattended deployments. |
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#TRPBF | E-grade (0°C to 85°C), identical electrical specs and pinout; no guaranteed operation above 85°C | Suitable for commercial-temperature applications only; not qualified for extended industrial or automotive use | Select LTC3605AIUF#TRPBF when full –40°C to 125°C operation is required; E-grade is cost-optimized for benign environments |
| MP2315DJ-LF-Z | Monolithic 5A buck with 4.5–28V input, fixed 500kHz freq, no PolyPhase or external sync; smaller 8-pin SOIC package | Lacks phase synchronization, tracking, or programmable frequency-intended for simpler, lower-cost single-rail designs | Choose MP2315DJ-LF-Z only for non-critical, space-constrained applications where multi-phase, precision sequencing, or wide VIN are unnecessary |
Compared with LTC3605EUF#TRPBF, the LTC3605AIUF#TRPBF guarantees full-spec operation across –40°C to 125°C, making it suitable for harsh environments; versus MP2315DJ-LF-Z, it offers superior design flexibility via PolyPhase®, external clock sync, and output tracking-but at higher component count and layout complexity.
Availability
LTC3605AIUF#TRPBF 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 extended temperature ranges and long production lifecycles.
Supply support for LTC3605AIUF#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 its high-performance power management portfolio with rigorous reliability testing and long-term product support.
The LTC3605A family was designed for high-efficiency, high-density synchronous buck conversion in thermally constrained and noise-sensitive applications-emphasizing PolyPhase scalability, precise output regulation, and robust protection features.
FAQ
What is the absolute maximum input voltage rating for the LTC3605AIUF#TRPBF?
The LTC3605AIUF#TRPBF has an absolute maximum PVIN and SVIN rating of 22V. Its VIN overvoltage protection activates at 23.5V (trip) and releases at 21.5V. Exceeding 22V risks permanent damage per Absolute Maximum Ratings. This 22V rating distinguishes the LTC3605A from the earlier LTC3605 (15V max), confirming the "A" suffix denotes enhanced voltage tolerance. Always respect the 22V limit in layout and system-level surge protection design.
Can the LTC3605AIUF#TRPBF operate without an external RT resistor?
No-the LTC3605AIUF#TRPBF requires an external resistor from RT (Pin 1) to SGND to set its base switching frequency between 800kHz and 4MHz. Without this resistor, the oscillator is undefined and regulation fails. The RT value directly determines frequency per f = 1.6×10¹¹ / RRT. While the device can synchronize to an external CLKIN signal, that signal must fall within ±30% of the RT-programmed frequency for reliable PLL lock-so RT remains mandatory even in sync mode.
How does the TRACK/SS pin function during power-up of the LTC3605AIUF#TRPBF?
During power-up, the LTC3605AIUF#TRPBF's internal 2.5µA current source pulls the TRACK/SS pin toward INTVCC. When a capacitor is connected, voltage ramps linearly, forcing the FB pin to track that voltage instead of the 0.6V reference-enabling controlled soft-start. Once TRACK/SS exceeds 0.6V, the internal reference resumes control and regulation transitions to normal operation. This mechanism prevents inrush current and allows precise sequencing with other rails, a core function confirmed in the LTC3605A datasheet Figure 1 and Pin Functions section.
Is the LTC3605AIUF#TRPBF pin-compatible with the LTC3605 series?
Yes-the LTC3605AIUF#TRPBF is explicitly stated as pin-compatible with the LTC3605 in the datasheet Features section. Both share identical 24-pin QFN (4mm × 4mm) footprints, pin assignments, and functional pin behavior. However, the LTC3605AIUF#TRPBF offers a higher 22V absolute maximum VIN (vs. 15V for LTC3605) and guaranteed –40°C to 125°C operation (I-grade), making it a direct drop-in replacement with enhanced voltage and temperature margins.
What thermal considerations apply to the exposed pad (Pin 25) of the LTC3605AIUF#TRPBF?
The exposed pad (Pin 25) of the LTC3605AIUF#TRPBF is electrically and thermally connected to PGND and must be soldered to a PCB copper pour for both electrical integrity and thermal performance. The datasheet specifies θJA = 37°C/W with proper pad soldering; omitting thermal vias or undersized copper significantly degrades this. For continuous 5A operation at high ambient temperatures, thermal vias (≥6×0.3mm) connecting the pad to inner-layer ground planes are strongly recommended to maintain TJ ≤ 125°C.
LTC3605AIUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LTC3605AIUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3605AIUF#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 LTC3605AIUF#TRPBF reliable?
The price and inventory of LTC3605AIUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3605AIUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3605AIUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3605AIUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3605AIUF#TRPBF?
LTC3605AIUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3605AIUF#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 LTC3605AIUF#TRPBF?
For technical support, including LTC3605AIUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3605AIUF#TRPBF requirements.
6.How does Aetrix verify that LTC3605AIUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3605AIUF#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 LTC3605AIUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3605AIUF#TRPBF?
All LTC3605AIUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3605AIUF#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 LTC3605AIUF#TRPBF part is unused and in its original packaging.
Return procedure for LTC3605AIUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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