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Analog Devices Inc. LTC3646IDE#PBF
- Part No.:
- LTC3646IDE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-WFDFN Exposed Pad
- Datasheet:
-
LTC3646IDE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 14DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,402
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Product details
Overview
LTC3646IDE#PBF from Analog Devices (formerly Linear Technology) is a 40V input, 1A synchronous step-down DC/DC converter with integrated high-side and low-side power MOSFETs, ±1% reference accuracy, 0.6V feedback threshold, and selectable Burst Mode® or forced continuous operation. It delivers regulated output voltages from 2.0V to 30V and supports automotive and industrial point-of-load applications requiring wide VIN tolerance and low quiescent current.
For engineers reviewing the LTC3646IDE#PBF datasheet, LTC3646IDE#PBF pinout, LTC3646IDE#PBF application, or LTC3646IDE#PBF equivalent, key selection criteria include its 4.0V–40V input range, 140µA no-load quiescent current in Burst Mode, 200kHz–3.0MHz programmable switching frequency, internal soft-start, and thermal shutdown protection across –40°C to +125°C junction temperature.
Technical Context
The LTC3646IDE#PBF implements a current-mode, controlled-on-time architecture that dynamically calculates switch on-time based on VON/VIN ratio and programmed frequency, enabling stable regulation across large step-down ratios without output overvoltage risk. Its valley-current sensing and error amplifier (300µS transconductance) provide precise load transient response and loop stability with internal or external compensation.
It features dual input rails-PVIN for power switches and SVIN for analog circuitry-with independent overvoltage lockout (43.5V/46V), undervoltage lockout (3.2V/3.5V), and robust short-circuit protection limiting valley current to 0.9A–1.5A. The PGOOD pin provides open-drain status with ±7.5% voltage window and 15–30µs filter time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.0V to 40V - supports 12V/24V/36V automotive and industrial bus inputs with transient margin |
| Output Current | 1A guaranteed - sustains full load across full temperature and input range with thermal derating |
| Feedback Reference | 0.6V ±1% - enables precise output programming via resistor divider; minimizes divider current error |
| Quiescent Current | 140µA typical in Burst Mode - extends battery life in always-on systems without sacrificing regulation |
| Switching Frequency | 200kHz to 3.0MHz - adjustable via RT resistor or external clock; balances efficiency vs. component size |
| Efficiency | Up to 95% - achieved at mid-load with optimized inductor and ceramic output capacitor |
| Operating Temp | –40°C to +125°C - qualified for extended-temperature industrial and under-hood automotive use |
Pinout & Package
Package: 14-lead (4mm × 3mm) plastic DFN with exposed PGND pad (Pin 15), θJA = 43°C/W. Requires soldering of exposed pad to PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SGND (Pin 1) | Analog Ground Reference | Low-noise return path for feedback and error amplifier; must be separated from noisy PGND until single-point connection |
| VFB (Pin 2) | Feedback Input | Connects to resistor divider; compares output voltage against 0.6V reference to regulate VOUT |
| ITH (Pin 3) | Error Amplifier Output | Compensation node; sets valley current limit; connect RC network for external loop tuning |
| RT (Pin 4) | Oscillator Programming | Resistor-to-ground sets switching frequency (200kHz–3.0MHz); tie to INTVCC for 2.25MHz default |
| VON (Pin 5) | On-Time Control Input | Connected to VOUT to scale on-time proportionally to output voltage, enabling constant-frequency operation |
| PGOOD (Pin 6) | Power-Good Status | Open-drain output pulled low if VFB deviates >±7.5% from 0.6V; includes 15–30µs glitch filter |
| MODE/SYNC (Pin 7) | Operation Mode Control | Tie to INTVCC for Burst Mode; tie to GND for forced continuous; drive with external clock for synchronization |
| PVIN (Pin 8) | High-Side Switch Supply | Primary power rail for top MOSFET; requires ≥10µF low-ESR ceramic decoupling to PGND |
| SW (Pin 9) | Switch Node | Connects to inductor and boost capacitor; carries high di/dt; layout critical for EMI and efficiency |
| BOOST (Pin 10) | Bootstrap Supply | Generates gate drive voltage for high-side MOSFET via SW–BOOST capacitor; swing = INTVCC to PVIN+INTVCC |
| INTVCC (Pin 11) | Internal 5.0V Regulator | Supplies control circuitry; decouple with ≥4.7µF low-ESR cap; disabled when RUN = low |
| EXTVCC (Pin 12) | External Bias Input | Optional 4.5V–6.0V supply for improved efficiency; tie to SGND if unused |
| RUN (Pin 13) | Enable Input | Active-high enable; threshold = 1.21V rising; hysteresis = 110mV; leakage <±1µA |
| SVIN (Pin 14) | Analog Circuit Supply | Must match PVIN for accurate on-time calculation; decouple with >1µF low-ESR capacitor to SGND |
| PGND (Pin 15) | Power Ground | Exposed thermal pad; must be soldered to solid PCB ground plane for thermal conduction and low-impedance return |
Key Features
| Feature | Design Value |
|---|---|
| Patented Controlled On-Time Architecture | Enables stable regulation across 40V:3V (13:1) step-down without output overvoltage risk |
| Selectably Optimized Efficiency Modes | Burst Mode reduces IQ to 140µA at no load; forced continuous eliminates subharmonic noise for sensitive analog loads |
| Integrated Dual Power MOSFETs | 200mΩ/120mΩ RDS(ON) at 5.5V - eliminates external FETs and gate drivers, reducing BOM count and layout complexity |
| Robust Protection Suite | Includes input overvoltage lockout (43.5V), short-circuit current limiting (0.9–1.5A), thermal shutdown, and PGOOD monitoring |
| Flexible Compensation & Synchronization | Supports internal or external loop compensation; MODE/SYNC accepts external clock up to 3.0MHz for EMI reduction |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 3.3V/5V logic and interface ICs in head units exposed to 12V/24V battery transients. IC Role / Device Role / Timing Role: Primary buck regulator converting unregulated vehicle battery to stable low-voltage rails. Use Value: 40V absolute max rating and 43.5V OVLO withstand cold-crank and load-dump events without latch-off. | Use Scenario: Generating isolated 12V and 5V supplies for sensor conditioning and digital I/O in factory automation controllers. IC Role / Device Role / Timing Role: Point-of-load regulator delivering clean, well-regulated power to mixed-signal subsystems. Use Value: 140µA Burst Mode IQ extends uptime in battery-backed standby modes while maintaining regulation. |
| Medical Portable Diagnostic Device | Telecom Remote Radio Unit |
Use Scenario: Supplying 1.8V/3.3V to FPGA, ADCs, and RF front-end in handheld ultrasound or glucose monitors. IC Role / Device Role / Timing Role: High-efficiency intermediate bus converter stepping down from Li-ion battery or 5V USB input. Use Value: 95% peak efficiency and 0.6V reference enable tight output tolerance (<±2%) critical for precision analog signal chains. | Use Scenario: Providing 5V bias to GaN power amplifiers and 3.3V to baseband processors in outdoor small-cell radios. IC Role / Device Role / Timing Role: Synchronous buck regulator operating from 28V or 48V intermediate bus with EMI-sensitive environment. Use Value: 200kHz–3.0MHz programmable frequency allows clock synchronization to avoid interference with RF bands. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | 4.5V–65V input, 1A, 1.5MHz fixed freq, no internal compensation, lower IQ (40µA) | Designed for automotive AEC-Q100 Grade 1; lacks programmable frequency and Burst Mode | Choose LM5164QDDARQ1 for higher VIN (>40V) or where ultra-low IQ dominates over flexibility |
| MP2451DT-LF-Z | 4.5V–36V input, 0.6A, 2MHz fixed freq, no PGOOD, no external sync, smaller package | Cost-optimized consumer-grade part; not rated for >85°C ambient or automotive environments | Choose MP2451DT-LF-Z only for non-automotive, low-power, cost-sensitive designs with ≤0.6A load |
Compared with LM5164QDDARQ1 and MP2451DT-LF-Z, the LTC3646IDE#PBF offers wider VIN range than the MP2451, superior thermal grade (–40°C to +125°C), programmable frequency, and Burst Mode operation-making it optimal for industrial and automotive applications demanding design flexibility and reliability across temperature extremes.
Availability
LTC3646IDE#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, and medical portable diagnostic devices requiring stable component supply, long-term lifecycle support, and extended-temperature qualification.
Supply support for LTC3646IDE#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, serving industrial, automotive, communications, and healthcare markets.
The LTC3646 belongs to Linear's high-voltage monolithic buck regulator product line, designed specifically for robust, wide-input industrial and automotive power conversion where reliability, efficiency, and thermal resilience are critical.
FAQ
What is the maximum input voltage the LTC3646IDE#PBF can safely handle?
The LTC3646IDE#PBF has an absolute maximum PVIN/SVIN rating of 45V, with overvoltage lockout triggered at 43.5V (rising) and 41.5V (falling). It is rated for continuous operation up to 40V input, making it suitable for 24V and 36V industrial buses and automotive applications with load-dump transients. Exceeding 45V risks permanent damage per Absolute Maximum Ratings.
Does the LTC3646IDE#PBF support output voltages below 2.0V?
No-the LTC3646IDE#PBF variant is specified for 2.0V to 30V output. For outputs down to 0.6V, the pin-compatible LTC3646-1 family (e.g., LTC3646IDE-1#PBF) must be used. The -1 suffix denotes the alternate feedback range; mixing variants risks incorrect regulation or instability due to different internal reference scaling.
How does the VON pin function in the LTC3646IDE#PBF?
The VON pin in the LTC3646IDE#PBF feeds the output voltage directly into the on-time controller, enabling the device to maintain constant switching frequency across wide VIN–VOUT ratios. When VON is tied to VOUT, the on-time becomes proportional to VOUT/VIN, preventing frequency collapse during deep step-down-critical for EMI control and predictable loop behavior.
Can the LTC3646IDE#PBF operate without external compensation components?
Yes-the LTC3646IDE#PBF supports internal compensation by connecting the ITH pin to INTVCC, simplifying design for standard applications. External compensation (via RCOMP/CCOMP) is optional and recommended only for specialized requirements such as enhanced transient response, specific phase margin targets, or unusual output capacitor ESR values.
What thermal considerations apply to the LTC3646IDE#PBF in a 14-lead DFN package?
The LTC3646IDE#PBF in the 14-lead DFN (4mm × 3mm) has θJA = 43°C/W. To maintain ≤125°C junction temperature at 1A load, the PCB must include a minimum 250mm² copper pour connected to the exposed PGND pad (Pin 15) with ≥4 thermal vias. Ambient temperature, airflow, and adjacent heat sources must be factored into thermal design-derating is required above 85°C ambient.
LTC3646IDE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-WFDFN 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):
- 40V
- Voltage - Output (Min/Fixed):
- 2V
- Voltage - Output (Max):
- 30V
- Current - Output:
- 1A
- Frequency - Switching:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-DFN (4x3)
LTC3646IDE#PBF FAQ
1.How can I place an order for LTC3646IDE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3646IDE#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 LTC3646IDE#PBF reliable?
The price and inventory of LTC3646IDE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3646IDE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3646IDE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3646IDE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3646IDE#PBF?
LTC3646IDE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3646IDE#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 LTC3646IDE#PBF?
For technical support, including LTC3646IDE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3646IDE#PBF requirements.
6.How does Aetrix verify that LTC3646IDE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3646IDE#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 LTC3646IDE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3646IDE#PBF?
All LTC3646IDE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3646IDE#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 LTC3646IDE#PBF part is unused and in its original packaging.
Return procedure for LTC3646IDE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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