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Analog Devices Inc. LTC3646IMSE#PBF
- Part No.:
- LTC3646IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3646IMSE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:558
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Product details
Overview
LTC3646IMSE#PBF from Analog Devices (formerly Linear Technology) is a 40V input, 1A synchronous step-down DC/DC converter in a thermally enhanced 16-lead MSOP package. It integrates high-side and synchronous power FETs, operates from 4.0V to 40V input, delivers 2.0V–30V output, and achieves up to 95% efficiency with 140µA no-load quiescent current in Burst Mode® operation - ideal for industrial point-of-load and automotive intermediate bus supplies.
For engineers reviewing the LTC3646IMSE#PBF datasheet, LTC3646IMSE#PBF pinout, LTC3646IMSE#PBF application, or LTC3646IMSE#PBF equivalent, key selection criteria include its 0.6V ±1% reference voltage, programmable 200kHz–3MHz switching frequency, controlled on-time architecture enabling large step-down ratios without overvoltage risk, and robust protection features including short-circuit and SVIN/PVIN overvoltage lockout.
Technical Context
The LTC3646IMSE#PBF implements a current-mode, monolithic synchronous buck topology with patented controlled on-time architecture. Its valley-current sensing and internal 0.6V reference enable precise regulation across wide VIN–VOUT differentials, while the VON pin ties on-time directly to output voltage for stable frequency behavior under varying loads.
It supports dual operating modes: Burst Mode® for ultra-low IQ (140µA typ.) at light loads, and forced continuous conduction mode for low-noise, ripple-sensitive applications. Frequency is set via RT resistor or synchronized externally, and internal soft-start (250–500µs), PGOOD monitoring, and thermal shutdown ensure system-level robustness.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.0V to 40V - supports wide-range industrial and automotive inputs without pre-regulation. |
| Output Current | 1A guaranteed - sufficient for FPGA core rails, microcontroller subsystems, and sensor interfaces. |
| Output Voltage Range | 2.0V to 30V - configurable via external resistor divider; avoids need for multiple fixed-output variants. |
| Reference Voltage | 0.6V ±1% - enables accurate, temperature-stable regulation critical for precision analog and digital loads. |
| Quiescent Current | 140µA typical in Burst Mode® - extends battery life in always-on systems and reduces standby power loss. |
| Switching Frequency | 200kHz to 3.0MHz - adjustable via RT resistor or external sync clock; balances size (smaller L/C at high f) vs. efficiency. |
| Package | 16-Lead MSOP with exposed PGND pad - provides superior thermal performance (θJA = 38°C/W) for high-power density layouts. |
Pinout & Package
Package: 16-Lead Plastic MSOP (MSE), thermally enhanced with exposed PGND pad (Pin 17), rated for –40°C to +125°C junction temperature.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SGND (Pin 1) | Analog Ground Reference | Low-noise return path for feedback and error amplifier; must be isolated from noisy power ground until joined at single point. |
| VFB (Pin 2) | Feedback Input | Connects to resistor divider from VOUT; compares against 0.6V internal reference to regulate output voltage. |
| ITH (Pin 3) | Error Amplifier Output / Compensation Node | Loop compensation point; connect RC network here for stability; tie to INTVCC for internal compensation. |
| RT (Pin 4) | Oscillator Programming Input | Resistor-to-ground sets switching frequency (200kHz–3MHz); connect to INTVCC for default 2.25MHz. |
| VON (Pin 5) | On-Time Control Input | Connected to VOUT to scale on-time proportionally to output voltage - enables constant-frequency operation across wide VOUT range. |
| PGOOD (Pin 6) | Power-Good Open-Drain Output | Asserts low when VFB deviates >7.5% from 0.6V; includes ~30µs filter to suppress transient glitches. |
| MODE/SYNC (Pin 7) | Mode Selection / Clock Sync Input | Tie to GND for forced continuous mode; to INTVCC for Burst Mode®; drive with external clock for synchronization. |
| PVIN (Pins 9,10) | Main Power Switch Supply | High-voltage input for top FET; requires ≥10µF low-ESR ceramic decoupling to PGND. |
| SW (Pin 11) | Switch Node | Connects to inductor and boost capacitor; carries high dv/dt switching waveform - minimize trace area. |
| BOOST (Pin 12) | Bootstrap Supply | Generates gate drive voltage for top FET via SW–BOOST capacitor; swing ranges from INTVCC to PVIN + INTVCC. |
| INTVCC (Pin 13) | Internal 5.0V Regulator Output | Supplies internal circuitry; decouple with ≥4.7µF low-ESR capacitor to PGND; disabled when RUN = low. |
| EXTVCC (Pin 14) | External Bias Input | Accepts 4.5V–6.0V supply to improve efficiency; otherwise connect to SGND. |
| RUN (Pin 15) | Enable Input | Active-high enable; threshold 1.21V (typ); hysteresis 110mV ensures noise immunity during power sequencing. |
| SVIN (Pin 16) | Control Circuit Supply | Must match PVIN voltage for accurate on-time calculation and stable frequency; decouple with >1µF low-ESR cap to SGND. |
| PGND (Exposed Pad) | Power Ground Return | Thermal and electrical ground for bottom FET and power paths; must be soldered to large PCB copper area for θJA = 38°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Reduces no-load IQ to 140µA while maintaining tight output regulation - essential for energy-sensitive remote sensors and battery-backed systems. |
| Controlled On-Time Architecture | Enables stable 40V→3.3V (12:1) or 40V→5V (8:1) conversion without output overvoltage risk, even under fast load transients. |
| Integrated Power FETs | Eliminates external MOSFETs and drivers; top/bottom RDS(ON) of 200mΩ/120mΩ @ 5.5V reduces conduction losses and simplifies layout. |
| Robust Protection Suite | Includes SVIN/PVIN overvoltage lockout (43.5V trip), short-circuit current limiting (~1.2A valley limit), thermal shutdown, and PGOOD monitoring. |
| Flexible Frequency Control | Supports resistor-programmed (200kHz–3MHz), internal default (2.25MHz), or external clock synchronization - aids EMI compliance and multi-rail coordination. |
Applications
| Industrial Point-of-Load Supply | Automotive Intermediate Bus Converter |
|---|---|
Use Scenario: Powering FPGA I/O banks or ARM Cortex-A series SoCs in factory automation controllers requiring clean, regulated 1.8V/3.3V rails from 24V DC bus. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering 1A at 95% peak efficiency; uses Burst Mode® during idle cycles to minimize system standby power. Use Value: Eliminates need for external FETs and loop compensation components, reducing BOM count by ≥7 parts while maintaining <±1% output accuracy over temperature. |
Use Scenario: Generating stable 5V or 12V intermediate rail from vehicle battery (9V–16V nominal, up to 40V load dump) for infotainment head units and ADAS camera modules. IC Role / Device Role / Timing Role: High-input-voltage buck controller with SVIN overvoltage lockout (43.5V) and thermal shutdown - ensures safe operation during cold-crank and load-dump events. Use Value: Withstands 40V transients without external TVS, and maintains regulation during 12V→5V conversion at full 1A load with <15mV line/load regulation. |
| Telecom Power Management | Test & Measurement Equipment |
Use Scenario: Providing isolated 3.3V/5V bias for optical transceivers and SerDes PHYs in 48V-powered telecom line cards where space and thermal constraints are severe. IC Role / Device Role / Timing Role: Compact, high-efficiency DC/DC stage placed near load; leverages 3mm × 4mm DFN or MSOP package and 38°C/W thermal resistance. Use Value: Achieves >92% efficiency at 500mA load from 48V input, reducing heat sink requirements and enabling dense board layouts in NEBS-compliant chassis. |
Use Scenario: Supplying low-noise 2.5V/3.3V rails for high-resolution ADCs, DACs, and RF front-ends in portable oscilloscopes and signal analyzers. IC Role / Device Role / Timing Role: Configured in forced continuous mode to eliminate Burst Mode® switching artifacts; synchronized to system clock to avoid beat frequencies. Use Value: Delivers <10mVpp output ripple at 1A load with external compensation, meeting stringent analog supply noise requirements without additional LDO post-regulation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8610EMSE#PBF | 42V input, 3.5A output, Silent Switcher® architecture; higher current but larger 16-lead MSOP footprint and no VON pin for on-time scaling. | Better EMI performance and higher output current; less suitable for wide-VOUT (>15V) or ultra-low-IQ (<100µA) designs. | Select LT8610EMSE#PBF when EMI compliance (CISPR 25 Class 5) or >1.5A load is required; LTC3646IMSE#PBF remains optimal for cost-sensitive, wide-output-voltage, low-quiescent designs. |
| TPS54240DGQR | 40V input, 2.5A output, external FETs required; no integrated synchronous rectifier; 75µA IQ in Eco-mode but lacks PGOOD and VON-based on-time control. | Lower BOM cost for high-volume production but increases design complexity, layout area, and thermal management burden. | Choose TPS54240DGQR only when maximum flexibility in FET selection and cost-per-watt optimization outweigh integration benefits and ease-of-use advantages of LTC3646IMSE#PBF. |
Compared with LT8610EMSE#PBF and TPS54240DGQR, the LTC3646IMSE#PBF uniquely combines wide 2.0V–30V output programmability, 140µA Burst Mode® IQ, and VON-based on-time scaling - making it the most balanced choice for compact, efficient, and flexible intermediate bus conversion where output voltage agility and low-light-load power matter.
Availability
LTC3646IMSE#PBF is available at Aetrix Electronics and suitable for industrial point-of-load supplies, automotive intermediate bus converters, and telecom power management requiring stable component supply, extended temperature support (–40°C to +125°C), and long-term lifecycle continuity.
Supply support for LTC3646IMSE#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, high-efficiency DC/DC conversion in harsh environments - emphasizing wide input range, integrated protection, and minimal external component count.
FAQ
What is the maximum input voltage rating for the LTC3646IMSE#PBF?
The LTC3646IMSE#PBF has an absolute maximum PVIN/SVIN rating of 45V, with guaranteed operation up to 40V. Its SVIN overvoltage lockout activates at 43.5V (typical) with 2.0V hysteresis, protecting internal FETs during load-dump transients commonly seen in automotive 24V systems. This makes the LTC3646IMSE#PBF suitable for applications where input surges up to 40V must be tolerated without external clamping.
Does the LTC3646IMSE#PBF support output voltages below 2.0V?
No - the LTC3646IMSE#PBF is the standard version with a 2.0V to 30V output voltage range. For sub-2.0V outputs down to 0.6V, the pin-compatible LTC3646-1 variant (e.g., LTC3646IMSE-1#PBF) must be used. The -1 suffix denotes the alternate feedback range; the LTC3646IMSE#PBF itself cannot regulate below 2.0V due to internal architecture constraints and minimum on-time limitations.
How does the VON pin function in the LTC3646IMSE#PBF?
The VON pin in the LTC3646IMSE#PBF feeds the output voltage directly into the on-time control loop, enabling the device to maintain constant switching frequency across wide input–output ratios. By connecting VON to VOUT, the on-time becomes proportional to VOUT/VIN, preventing frequency collapse at high step-down ratios - a key advantage over conventional constant-frequency controllers that require complex external compensation.
Can the LTC3646IMSE#PBF be synchronized to an external clock?
Yes - the MODE/SYNC pin of the LTC3646IMSE#PBF accepts an external clock signal (0.2MHz to 3.0MHz) to synchronize switching frequency. When driven externally, the device operates in forced continuous mode and adjusts its top-FET on-time to match the applied clock. An RT resistor must still be connected to set internal oscillator gain and ensure stable lock; the external clock overrides frequency but not modulation behavior.
What thermal performance can be expected from the LTC3646IMSE#PBF in MSOP package?
The LTC3646IMSE#PBF in the 16-lead MSOP (MSE) package has a specified θJA of 38°C/W when mounted on a standard 2-layer JEDEC test board with the exposed PGND pad fully soldered to a 1-in² copper area. Under 1A load at 12V→5V conversion, junction temperature rise remains below 45°C above ambient - enabling reliable operation in sealed enclosures or stacked PCB assemblies without forced airflow.
LTC3646IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) 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:
- 16-MSOP-EP
LTC3646IMSE#PBF FAQ
1.How can I place an order for LTC3646IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3646IMSE#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 LTC3646IMSE#PBF reliable?
The price and inventory of LTC3646IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3646IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LTC3646IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3646IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3646IMSE#PBF?
LTC3646IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3646IMSE#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 LTC3646IMSE#PBF?
For technical support, including LTC3646IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3646IMSE#PBF requirements.
6.How does Aetrix verify that LTC3646IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3646IMSE#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 LTC3646IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LTC3646IMSE#PBF?
All LTC3646IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3646IMSE#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 LTC3646IMSE#PBF part is unused and in its original packaging.
Return procedure for LTC3646IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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