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Texas Instruments LMS3655AMRNLT
- Part No.:
- LMS3655AMRNLT
- Manufacturer:
- Texas Instruments
- Package:
- 22-PowerVFQFN
- Datasheet:
-
LMS3655AMRNLT.pdf
- Description:
- IC REG BUCK ADJ 5.5A 22VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:250
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Product details
Overview
LMS3655AMRNLT from Texas Instruments is a 5.5-A, 36-V synchronous step-down DC-DC converter in a 4-mm × 5-mm VQFN-HR package, featuring 400-kHz fixed switching frequency, adjustable output (1 V to 20 V), ±1.5% reference voltage tolerance, and integrated compensation. It delivers 96% peak efficiency at 12 V → 5 V conversion and supports noise-sensitive industrial power rails.
For engineers reviewing the LMS3655AMRNLT datasheet, LMS3655AMRNLT pinout, LMS3655AMRNLT application, or LMS3655AMRNLT equivalent, key selection considerations include input voltage range (3.5 V to 36 V), continuous 5.5-A load capability, RESET flag with 3-ms release timer, FPWM mode control, and thermal performance up to +150°C junction temperature.
Technical Context
The LMS3655AMRNLT employs peak current mode control with frequency foldback architecture to maintain regulation down to 650-mV dropout and enable seamless PWM-to-PFM transition. Its flip-chip construction minimizes switch-node ringing and radiated EMI via partial magnetic field cancellation.
It integrates an internal 3.1-V LDO (VCC), bootstrap gate drive (CBOOT), open-drain RESET with built-in 24-µs glitch filter and 3-ms assertion delay, and dual power ground (PGND1/PGND2) with analog ground (AGND) separation for noise immunity in high-performance industrial systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.5 V to 36 V - supports wide industrial input sources including 24-V bus with 42-V transient tolerance. |
| Output Current | 5.5 A continuous - sustains full-load operation without external current sharing or derating at +125°C ambient. |
| Switching Frequency | 400 kHz ±10% - enables compact 10-µH inductor and low-ESR ceramic output capacitors (3 × 47 µF). |
| Efficiency (12 V → 5 V) | 96% peak - reduces thermal load in enclosed enclosures and extends battery runtime in backup systems. |
| Quiescent Current | 32 µA at 3.3 VOUT, no load - eliminates need for external backup LDO in always-on subsystems. |
| Reference Voltage Tolerance | ±1.5% - ensures tight output regulation across –40°C to +125°C ambient for precision analog supplies. |
| Duty Cycle Range | Up to 98% - maintains regulation with only 650-mV VIN–VOUT differential, critical for low-dropout 3.3-V rail generation from 4-V inputs. |
Pinout & Package
Package: VQFN-HR (RNL), 22-pin, 4.00 mm × 5.00 mm, 0.5-mm pitch, wettable flanks for optical solder inspection.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (PVIN1, PVIN2) | Primary power input | Dual high-current input pins tied together on PCB; accept 3.5–36 V with 42-V transient rating. |
| SW | Switch node | Connects directly to 10-µH inductor; low-ringing waveform due to flip-chip layout and minimized parasitic inductance. |
| FB | Feedback input | Resistor-divider input referenced to AGND; sets output from 1 V to 20 V with ±1.5% accuracy. |
| EN | Enable control | Logic-level input (1.7 V threshold); pulls RESET low when disabled; no floating allowed. |
| RESET | Open-drain fault flag | Asserts low during EN=low or VOUT out-of-tolerance; includes 24-µs glitch filter and 3-ms release timer. |
| FPWM | Mode select | High = forced PWM (fixed 400-kHz), low = automatic light-load mode (diode emulation); prevents audible noise. |
| BIAS | Auxiliary bias supply | Connected to VOUT to reduce quiescent current; required for >15-V outputs or when BIAS is grounded. |
| AGND / PGND1 / PGND2 | Analog & power grounds | Separate AGND (reference plane) and dual PGND (high-current return paths) must be tied together at single point under device. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated compensation | Eliminates external loop compensation components - reduces BOM count and layout sensitivity. |
| Pseudo-random spread spectrum | Reduces EMI peak emissions by ±3% frequency dither - simplifies EMC compliance in medical and telecom systems. |
| Automatic light-load mode | Switches to diode-emulation PFM below ~200 mA - maintains >90% efficiency at microamp loads. |
| Built-in soft-start | 4-ms internal ramp - prevents inrush current and output overshoot during power-up. |
| Thermal shutdown | 160°C trip with 15°C hysteresis - protects against sustained overload or poor heatsinking in sealed enclosures. |
Applications
| Industrial PLC Power Supply | Noise-Sensitive Medical Sensor Rail |
|---|---|
Use Scenario: Distributed I/O module requiring stable 5-V/3.3-V rails from 24-V factory bus with surge immunity. IC Role / Device Role / Timing Role: Primary buck regulator delivering 5.5-A continuous current with RESET supervision for CPU reset sequencing. Use Value: 42-V transient tolerance eliminates need for upstream TVS; 96% efficiency reduces heatsink size in DIN-rail enclosures. | Use Scenario: Portable EEG amplifier needing ultra-low-noise 3.3-V analog supply isolated from digital switching noise. IC Role / Device Role / Timing Role: Low-EMI buck converter with minimized switch-node ringing and separate AGND/PGND planes. Use Value: Flip-chip layout and spread spectrum reduce conducted/radiated emissions below CISPR 11 Class B limits. |
| Telecom Remote Radio Unit | Automotive ADAS Camera Module |
Use Scenario: Outdoor small-cell base station operating from -40°C to +85°C ambient with 48-V PoE-derived input. IC Role / Device Role / Timing Role: High-reliability 12-V intermediate rail generator with SYNC input for system-wide clock alignment. Use Value: –40°C to +150°C junction rating and 29.4°C/W θJA (PCB-optimized) ensure long-term reliability without active cooling. | Use Scenario: In-cabin camera module powered from vehicle battery (9–16 V) requiring 1.8-V core and 3.3-V I/O rails. IC Role / Device Role / Timing Role: Input-capable buck converter supporting cold-crank (3.5-V min) with FPWM mode for deterministic timing. Use Value: 3.5-V minimum input and 98% max duty cycle enable uninterrupted operation during engine start events. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM61480RPHR | 8-A rated, 2.5-V to 36-V input, 2.1-MHz switching, no integrated BIAS pin | Better suited for space-constrained designs needing higher current; lacks BIAS-assisted low-IQ mode | Select LM61480RPHR when >5.5-A load or >1-MHz frequency is required; verify BIAS functionality not needed. |
| TPS54560RGYR | 5.5-A rated, 3.5-V to 60-V input, 100-kHz to 2.5-MHz adjustable frequency, no spread spectrum | Higher input voltage range ideal for 48-V industrial systems; lacks integrated RESET and spread spectrum | Choose TPS54560RGYR for 60-V input tolerance or programmable frequency; add external supervisor if RESET required. |
Compared with LM61480RPHR and TPS54560RGYR, the LMS3655AMRNLT uniquely combines 5.5-A capability, 400-kHz fixed frequency, integrated RESET with glitch filtering, and BIAS-assisted ultra-low IQ - making it optimal for thermally constrained, noise-sensitive industrial and medical applications where component count and EMI are critical.
Availability
LMS3655AMRNLT is available at Aetrix Electronics and suitable for industrial PLCs, medical sensor modules, telecom remote radio units, and automotive ADAS camera systems requiring stable component supply with extended temperature support and low EMI.
Supply support for LMS3655AMRNLT 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
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, designing and manufacturing analog ICs, embedded processors, and power management solutions for industrial, automotive, and communications markets.
The LMS3655AMRNLT belongs to TI's high-performance synchronous buck regulator product line, engineered specifically for demanding industrial environments requiring wide input range, low EMI, and high reliability across –40°C to +150°C junction temperatures.
FAQ
What is the minimum input voltage required for LMS3655AMRNLT to regulate a 3.3-V output at full 5.5-A load?
The LMS3655AMRNLT requires a minimum input voltage of 3.8 V after startup to maintain regulation at 3.3 V and 5.5-A load, per the System Characteristics table. This is enabled by its frequency foldback architecture and 98% maximum duty cycle, allowing operation with only 650-mV VIN–VOUT differential. Below this, dropout behavior occurs.
Does LMS3655AMRNLT support synchronization to an external clock, and what is the valid frequency range?
Yes, the LMS3655AMRNLT supports external synchronization via the SYNC pin, which accepts a rising-edge-triggered clock signal between 250 kHz and 500 kHz. The internal oscillator locks to the external source within this range, enabling system-level timing coordination and EMI reduction through frequency alignment.
How does the RESET output of LMS3655AMRNLT behave when the EN pin is pulled low?
When EN is pulled low, the LMS3655AMRNLT forces the open-drain RESET output low regardless of output voltage status. This provides a deterministic system reset signal during disable events. RESET remains functional down to 1.5 V input voltage and includes a 24-µs glitch filter and 3-ms release timer after regulation is re-established.
Can LMS3655AMRNLT operate with an output voltage higher than 15 V, and what design considerations apply?
Yes, the LMS3655AMRNLT supports output voltages up to 20 V. For outputs above 15 V, the BIAS pin must be grounded or supplied externally - it cannot be connected to VOUT. This requirement is specified in the Recommended Operating Conditions table and ensures proper biasing of internal circuitry at elevated output voltages.
What thermal metrics define the PCB-level thermal performance of LMS3655AMRNLT in its VQFN-HR package?
The LMS3655AMRNLT exhibits a junction-to-ambient thermal resistance (RθJA) of 29.4°C/W when mounted on a thermally optimized 4-layer FR4 PCB. Its junction-to-board (RθJB) is 5.4°C/W, indicating strong heat conduction into the PCB copper layers - critical for passive cooling in fanless industrial enclosures.
LMS3655AMRNLT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 22-PowerVFQFN
- 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):
- 3.5V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1V
- Voltage - Output (Max):
- 15V
- Current - Output:
- 5.5A
- Frequency - Switching:
- 250kHz ~ 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 22-VQFN-HR (5x4)
LMS3655AMRNLT FAQ
1.How can I place an order for LMS3655AMRNLT through Aetrix?
Please submit a Request for Quotation (RFQ) for LMS3655AMRNLT 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 LMS3655AMRNLT reliable?
The price and inventory of LMS3655AMRNLT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMS3655AMRNLT is usually 5 days.
3.What payment methods are accepted for LMS3655AMRNLT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMS3655AMRNLT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMS3655AMRNLT?
LMS3655AMRNLT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMS3655AMRNLT 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 LMS3655AMRNLT?
For technical support, including LMS3655AMRNLT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMS3655AMRNLT requirements.
6.How does Aetrix verify that LMS3655AMRNLT is sourced from the original manufacturer or authorized distributors?
All LMS3655AMRNLT 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 LMS3655AMRNLT meets industry standards.
7.What is the process for return or replacement of LMS3655AMRNLT?
All LMS3655AMRNLT units undergo pre-shipment inspection (PSI). If there is an issue with LMS3655AMRNLT, 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 LMS3655AMRNLT part is unused and in its original packaging.
Return procedure for LMS3655AMRNLT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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