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Analog Devices Inc. LTC3649IUFD#TRPBF
- Part No.:
- LTC3649IUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC3649IUFD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 4A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,575
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Product details
Overview
LTC3649IUFD#TRPBF from Analog Devices is a 60V input, 4A synchronous monolithic step-down regulator with rail-to-rail programmable output (0V to VIN – 0.5V), single-resistor VOUT programming, and peak current mode control. It delivers up to 4A at 5V with 95% efficiency (12VIN), features ±0.8% output voltage accuracy, and supports MPPT input voltage regulation for solar applications.
For engineers reviewing the LTC3649IUFD#TRPBF datasheet, LTC3649IUFD#TRPBF pinout, LTC3649IUFD#TRPBF application, or LTC3649IUFD#TRPBF equivalent, key selection criteria include its 3.1V–60V input range, programmable 300kHz–3MHz switching frequency, Burst Mode®/forced continuous mode selection, accurate ±4% current monitoring without sense resistor, and thermally enhanced 28-lead 4mm × 5mm QFN package.
Technical Context
The LTC3649IUFD#TRPBF employs a peak current mode architecture with internal compensation, enabling fast transient response and inherent cycle-by-cycle current limiting. Its error amplifier adjusts ITH voltage based on VOUT vs. ISET reference, while the 50µA precision ISET bias enables rail-to-rail output programming via a single resistor.
It integrates 110mΩ top and 50mΩ bottom N-channel MOSFETs, supports input voltage regulation (VINREG) for MPPT, and provides programmable wire-drop compensation using IMON feedback. MODE/SYNC pin enables Burst Mode® (high light-load efficiency) or forced continuous mode (low ripple), and allows external clock synchronization within ±50% of programmed frequency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.1V to 60V - supports wide-input industrial, automotive, and solar systems without pre-regulation. |
| Output Current | Up to 4A - sufficient for powering FPGAs, DSPs, and multi-rail subsystems from a single buck stage. |
| Output Voltage Range | 0V to (VIN – 0.5V) - enables true rail-to-rail adjustment including zero-VOUT and high-duty-cycle operation. |
| Switching Frequency | 300kHz to 3MHz (resistor-programmable) - allows optimization of size (high fSW) vs. efficiency (low fSW) and EMI filtering. |
| Quiescent Current | 440µA (regulated IQ), 18µA (shutdown) - enables low-power standby in battery-backed or energy-harvesting systems. |
| Current Monitoring Accuracy | ±4% without external sense resistor - reduces BOM cost and PCB area while enabling precise load telemetry and protection. |
| Output Voltage Accuracy | ±0.8% - ensures stable power delivery to sensitive analog and digital loads across temperature and line/load variations. |
Pinout & Package
Package: 28-lead (4mm × 5mm) plastic QFN with exposed thermal pad (Pin 29 = SGND), rated for –40°C to +125°C junction temperature (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PGND (Pins 1, 2, 26–28) | Power ground return for high-current switch paths | Must be connected to low-impedance PCB ground plane; multiple pins reduce conduction loss and improve thermal dissipation. |
| VIN (Pins 3, 4) | Main input supply connection | Accepts 3.1V–60V; dual pins reduce IR drop and enhance current handling for high-power operation. |
| RUN (Pin 5) | Enable/disable logic input with hysteresis | 1.2V rising threshold; used with resistor divider to set precise VIN undervoltage lockout (UVLO) point. |
| SGND (Pins 6, 29) | Signal ground reference | Exposes thermal pad (Pin 29); must be soldered to PCB ground for electrical integrity and thermal performance. |
| MODE/SYNC (Pin 7) | Operating mode control and clock sync input | GND = Burst Mode®; floating = forced continuous; external clock = synchronized FC mode with ±50% capture range. |
| PGOOD (Pin 8) | Open-drain power-good status indicator | Asserts low when VPGFB < 0.555V or > 0.645V; enables system sequencing and fault reporting. |
| IMON (Pin 10) | Output current monitor output | Sinks 1/40,000× IOUT; enables resistor-based current sensing and programmable current limit without sense resistor. |
| ISET (Pin 14) | 50µA precision reference and EA+ input | VOUT = 50µA × RSET; sets output voltage with ±0.8% accuracy; capacitor adds soft-start functionality. |
| ITH (Pin 15) | Error amplifier output and current limit threshold | Voltage controls peak inductor current; tying to INTVCC enables internal compensation (no external network required). |
| RT (Pin 12) | Oscillator frequency programming node | Resistor to GND sets fSW from 300kHz to 3MHz; determines inductor size, efficiency, and EMI profile. |
Key Features
| Feature | Design Value |
|---|---|
| Rail-to-rail output programming | VOUT adjustable from 0V to (VIN – 0.5V) using one external resistor - eliminates need for post-regulators in wide-output-range systems. |
| Accurate input voltage regulation (VINREG) | Programmable 2.0V threshold enables MPPT tracking or input hold-up by reducing peak current when VIN drops - critical for solar chargers and backup supplies. |
| Integrated MOSFETs with low RDS(ON) | 110mΩ top / 50mΩ bottom N-channel switches - minimize conduction loss and simplify layout versus discrete solutions. |
| Programmable cable drop compensation | Uses IMON feedback and ISET to dynamically raise VOUT proportional to load current - maintains accurate voltage at remote point-of-load without added components. |
| Burst Mode® operation | Reduces quiescent current to <400µA at light loads while maintaining single-burst behavior - extends battery life without sacrificing start-up speed or output stability. |
Applications
| Industrial Power Supply | Automotive Infotainment System |
|---|---|
Use Scenario: 24V vehicle battery powers a 5V/4A rail for display controller and audio codec in harsh ambient conditions. IC Role / Device Role / Timing Role: Primary DC/DC buck regulator delivering regulated 5V with input surge tolerance up to 60V and thermal robustness to 125°C. Use Value: Eliminates need for external TVS and pre-regulator; ±0.8% accuracy ensures stable operation of timing-critical video interfaces. | Use Scenario: 12V–48V variable input from engine alternator or PoE-derived supply powers FPGA-based ADAS processing unit. IC Role / Device Role / Timing Role: High-efficiency, wide-VIN step-down regulator supplying 3.3V/4A with programmable current limit for fault containment. Use Value: 95% efficiency at full load minimizes thermal stress in sealed enclosures; IMON enables real-time load diagnostics for functional safety compliance. |
| Solar MPPT Charge Controller | Programmable Test Equipment Power |
Use Scenario: PV array (up to 60V) feeds a battery charging circuit requiring dynamic input voltage regulation to track maximum power point. IC Role / Device Role / Timing Role: Buck converter with VINREG loop actively modulating peak current to maintain optimal input voltage during varying irradiance. Use Value: Integrated VINREG function replaces external op-amp circuits; ±4% current monitoring enables precise charge current control without shunt resistor. | Use Scenario: Bench power supply module generating user-adjustable 1.2V–24V outputs with 4A capability and digital telemetry interface. IC Role / Device Role / Timing Role: Programmable output buck regulator with single-resistor VOUT setting, RT-based frequency tuning, and IMON-based current readback. Use Value: Rail-to-rail output range and 50µA ISET reference enable 0.1% resolution over full span; soft-start via ISET capacitor prevents inrush during voltage changes. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3649EUFD#TRPBF | Same silicon, –40°C to +85°C operating temperature range (vs. –40°C to +125°C for LTC3649IUFD#TRPBF) | Suitable for commercial/industrial environments without extended thermal requirements | Select when ambient temperature remains below 85°C; lower cost alternative where full industrial temp grade is unnecessary. |
| LT8640SIV#PBF | 42V max input, 4A, Silent Switcher® architecture; higher EMI immunity but no VINREG or IMON functions | Preferred for noise-sensitive RF/analog systems; lacks MPPT and current monitoring capabilities | Choose when ultra-low EMI is mandatory and input voltage stays ≤42V; not suitable for solar MPPT or current telemetry use cases. |
Compared with LTC3649EUFD#TRPBF, the LTC3649IUFD#TRPBF offers guaranteed operation up to +125°C junction temperature - essential for under-hood automotive or high-density industrial designs. Versus LT8640SIV#PBF, it provides unique VINREG and IMON features for energy harvesting and smart load management, albeit with higher radiated emissions.
Availability
LTC3649IUFD#TRPBF is available at Aetrix Electronics and suitable for industrial power supplies, automotive infotainment systems, solar MPPT charge controllers, and programmable test equipment requiring stable component supply across extended temperature ranges.
Supply support for LTC3649IUFD#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) is a global leader in high-performance analog, mixed-signal, and power management ICs, serving industrial, automotive, communications, and healthcare markets.
The LTC3649IUFD#TRPBF belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for rugged, wide-input applications demanding precision regulation, integrated power stages, and advanced telemetry features like current monitoring and input voltage regulation.
FAQ
What is the maximum input voltage rating for the LTC3649IUFD#TRPBF?
The LTC3649IUFD#TRPBF has an absolute maximum input voltage rating of 64V, with recommended continuous operation up to 60V. It includes built-in VIN overvoltage lockout that suspends switching when VIN exceeds 68V (typical), protecting internal MOSFETs from transients. Operation above 60V is not specified in the electrical characteristics and may compromise long-term reliability or parametric performance.
How does the LTC3649IUFD#TRPBF achieve accurate output current monitoring without a sense resistor?
The LTC3649IUFD#TRPBF uses an internal current mirror to generate a precise 1/40,000-scale replica of average inductor current at the IMON pin. With ±4% accuracy over temperature and line/load, this eliminates the need for external shunt resistors. A resistor from IMON to GND converts current to voltage (VIMON = IOUT/40k × RIMON), enabling both telemetry and programmable current limiting when VIMON reaches 2V.
Can the LTC3649IUFD#TRPBF operate in full dropout mode (VOUT ≈ VIN)?
No - the LTC3649IUFD#TRPBF cannot operate in true 100% duty cycle dropout. Two architectural limits prevent it: (1) ISET current accuracy degrades when VISET approaches VIN (guaranteed only when VISET is ≥500mV below VIN), and (2) BOOST capacitor refresh requires periodic bottom-FET conduction. The practical minimum dropout is ~0.5V, limiting VOUT to (VIN – 0.5V) maximum.
What is the purpose of the VINREG pin on the LTC3649IUFD#TRPBF?
The VINREG pin on the LTC3649IUFD#TRPBF enables input voltage regulation by monitoring a resistor divider from VIN to GND. When the divided voltage falls below 2.0V (typical), the regulator reduces peak inductor current to maintain constant input voltage - a key feature for MPPT solar chargers and momentary hold-up supplies. If unused, VINREG must be tied to INTVCC to disable the loop.
Does the LTC3649IUFD#TRPBF require external compensation components?
No - the LTC3649IUFD#TRPBF features internal compensation. Connecting the ITH pin directly to INTVCC activates the internal network, eliminating the need for external Type II or III compensation components. This simplifies design, reduces BOM count, and improves consistency across production units while retaining full stability over the entire operating range.
LTC3649IUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-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):
- 3.1V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 0V
- Voltage - Output (Max):
- 55V
- Current - Output:
- 4A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC3649IUFD#TRPBF FAQ
1.How can I place an order for LTC3649IUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3649IUFD#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 LTC3649IUFD#TRPBF reliable?
The price and inventory of LTC3649IUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3649IUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3649IUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3649IUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3649IUFD#TRPBF?
LTC3649IUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3649IUFD#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 LTC3649IUFD#TRPBF?
For technical support, including LTC3649IUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3649IUFD#TRPBF requirements.
6.How does Aetrix verify that LTC3649IUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3649IUFD#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 LTC3649IUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3649IUFD#TRPBF?
All LTC3649IUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3649IUFD#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 LTC3649IUFD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3649IUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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