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Texas Instruments LMS3655MQRNLTQ1
- Part No.:
- LMS3655MQRNLTQ1
- Manufacturer:
- Texas Instruments
- Package:
- 22-PowerVFQFN
- Datasheet:
-
LMS3655MQRNLTQ1.pdf
- Description:
- IC REG BUCK ADJ 5.5A 22VQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,802
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Product details
Overview
LMS3655MQRNLTQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive synchronous buck converter delivering up to 5.5 A output current, 36-V max input, 400-kHz fixed switching frequency, ±1.5% reference voltage tolerance, and 18-µA quiescent current at 3.3 VOUT with no load - optimized for USB charging and surround-view ECU power rails.
For engineers reviewing the LMS3655MQRNLTQ1 datasheet, LMS3655MQRNLTQ1 pinout, LMS3655MQRNLTQ1 application, or LMS3655MQRNLTQ1 equivalent, this page delivers verified technical context, validated pin functions, confirmed automotive-grade thermal and EMI performance, and real-world selection guidance for high-reliability 12-V/24-V automotive subsystems.
Technical Context
The LMS3655MQRNLTQ1 implements peak-current-mode control with built-in compensation, enabling stable regulation across 3.9–36-V input while supporting 1–20-V adjustable output (or fixed 3.3 V/5 V). Its flip-chip VQFN package minimizes parasitic inductance, reducing switch-node ringing and conducted EMI without external filters.
It features dual-mode operation: automatic light-load PFM for ultra-low IQ (18 µA), and pin-selectable forced PWM (FPWM) for consistent 400-kHz switching during transient loads. The integrated RESET output includes 3-ms release timer and internal glitch filtering, eliminating need for external supervisory ICs in safety-critical ECUs.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Current | 5.5 A continuous - supports high-power USB PD and camera module rails without derating at 125°C ambient. |
| Input Voltage Range | 3.9 V to 36 V - withstands cold-crank (3.5 V min functional) and load-dump transients up to 42 V for ≤500 ms. |
| Switching Frequency | 400 kHz ±10% - enables compact 2.2-µH inductors and low-ESR ceramic capacitors in space-constrained modules. |
| Quiescent Current | 18 µA at 3.3 VOUT, no load - extends battery runtime in always-on vehicle domains (e.g., driver monitoring). |
| Reference Tolerance | ±1.5% over –40°C to +125°C - ensures tight output regulation across automotive temperature extremes. |
| Efficiency Peak | 96% at 12 V → 5 V, 3.5 A - reduces thermal stress and eliminates need for heatsinks in sealed enclosures. |
| RESET Output | Open-drain with 3-ms release timer and 24-µs glitch filter - provides clean, debounced system reset without external RC networks. |
Pinout & Package
Package: 22-pin VQFN (RNL), 4.0 mm × 5.0 mm, wettable flanks - enables automated optical solder-joint inspection per IPC-A-610.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC | Internal 3.1-V LDO output | Power source for internal control circuitry; requires 4.7-µF bypass capacitor to AGND. |
| CBOOT | Bootstrap capacitor node | Drives high-side MOSFET gate; connects via 470-nF capacitor to SW pin for reliable turn-on. |
| SYNC | Frequency synchronization input | Accepts 250–500 kHz external clock (rising-edge triggered); enables system-level EMI reduction. |
| PVIN1 / PVIN2 | Main power inputs | Parallel high-current VIN paths; must be shorted on PCB to minimize loop inductance and thermal resistance. |
| SW | Switch node | Connects directly to power inductor; low-ringing waveform due to flip-chip layout and minimized parasitics. |
| PGND1 / PGND2 | Power ground terminals | Low-impedance return for internal MOSFETs; must tie together and connect to AGND at single point. |
| AVIN | Analog supply input | Bias source for error amplifier and reference; connected to PVIN on PCB for noise immunity. |
| FPWM | Mode control input | High = forced PWM (no frequency variation); low = automatic light-load mode; must not float. |
| EN | Enable input | Active-high logic; 1.7–2.0 V threshold with 0.5 V hysteresis; supports direct connection to 12-V rail via resistor divider. |
| RESET | Open-drain status flag | Asserts low during fault (UVLO, thermal shutdown, EN=low); includes internal 3-ms release timer. |
| AGND | Analog ground reference | Reference for FB, VREF, and internal circuits; must connect to PGND at single star point. |
| FB | Feedback input | Monitors output voltage; for adjustable version, sets VOUT = 1 V × (1 + R1/R2) with 1-V reference. |
| BIAS | Auxiliary bias regulator input | Connected to output for improved efficiency; grounded or externally powered when VOUT > 15 V. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated compensation network | Eliminates external Type-II/III compensation components - reduces BOM count and layout sensitivity. |
| Spread-spectrum modulation | ±3% frequency dithering - lowers peak conducted EMI by >10 dB without altering filter design. |
| Automatic light-load PFM mode | Maintains >85% efficiency at 1-mA load - critical for always-on automotive domains with microamp-level standby budgets. |
| Thermal shutdown with hysteresis | 160°C trip, 15°C hysteresis - prevents latch-up and enables safe auto-recovery after transient overload. |
| Wettable flank package | Enables AOI-compatible solder-joint inspection - meets automotive process validation requirements without X-ray. |
Applications
| Automotive USB Charging | Driver Monitoring System |
|---|---|
Use Scenario: Powering dual-port USB-C modules in center console with 5-V/3-A and 9-V/2-A PD profiles. IC Role / Device Role / Timing Role: Primary 12-V-to-5-V buck regulator with fast transient response and low-noise output for USB PHY and controller. Use Value: 96% peak efficiency and 18-µA quiescent current extend battery life during ignition-off monitoring; spread spectrum reduces EMI interference with nearby radar receivers. |
Use Scenario: Supplying image signal processor (ISP), CMOS sensor, and IR illuminator in cabin-facing driver attention system. IC Role / Device Role / Timing Role: High-reliability 3.3-V power rail with RESET supervision ensuring clean boot and fault detection during camera initialization. Use Value: AEC-Q100 Grade 1 qualification and –40°C to +125°C operation guarantee uptime in extreme cabin temperatures; FPWM mode locks switching frequency during ISP burst processing. |
| Surround-View ECU | Mechanically Scanning LiDAR |
Use Scenario: Powering four 3.3-V image processors and FPGA-based stitching engine in 360° camera fusion unit. IC Role / Device Role / Timing Role: Main 12-V-to-3.3-V converter with SYNC input synchronized to system master clock for deterministic timing alignment. Use Value: 400-kHz fixed frequency and low EMI enable co-location with high-speed MIPI CSI-2 interfaces; wettable flanks ensure solder joint reliability under vibration. |
Use Scenario: Generating 5-V rail for motor driver ICs and 3.3-V rail for FPGA control logic in rotating LiDAR head assemblies. IC Role / Device Role / Timing Role: Dual-output capable buck (via multiple LMS3655MQRNLTQ1 units) delivering isolated, ripple-free supplies for precision analog front-end and digital control. Use Value: 36-V input range accommodates wide battery swing (9–16 V); 5.5-A capability supports stepper motor bursts without output droop or thermal throttling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM61480QRNXTQ1 | 8-A output, 2.5-V to 36-V input, 2.1-MHz switching, lower IQ (12 µA) | Better suited for space-constrained ADAS domain controllers requiring higher current density | Select when board area is limited and >6-A peak load is required; requires redesign for higher-frequency magnetics and layout. |
| TPS54561QRTQRQ1 | 5.5-A output, 3.5-V to 60-V input, 100–2500-kHz adjustable frequency, no spread spectrum | Preferred for heavy-duty commercial vehicles with 48-V architectures and strict EMC test margins | Choose for 48-V battery systems or where programmable frequency avoids sensitive bands; lacks integrated RESET and wettable flanks. |
Compared with LM61480QRNXTQ1 and TPS54561QRTQRQ1, the LMS3655MQRNLTQ1 offers superior EMI performance via spread spectrum and a production-validated automotive RESET function, making it optimal for cost-sensitive, thermally constrained 12-V/24-V ECU designs where board-level supervision integration is mandatory.
Availability
LMS3655MQRNLTQ1 is available at Aetrix Electronics and suitable for automotive USB charging, driver monitoring systems, surround-view ECUs, mechanically scanning LiDAR, and vehicle-to-vehicle communication modules requiring stable component supply across extended temperature and lifecycle requirements.
Supply support for LMS3655MQRNLTQ1 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 leader specializing in analog, embedded processing, and automotive-grade power management ICs with over 40 years of automotive qualification experience.
The LMS3655-Q1 product line delivers high-current, low-EMI synchronous buck converters for AEC-Q100 Grade 1 automotive subsystems - designed specifically for infotainment, ADAS, and body electronics demanding robustness, small footprint, and seamless integration.
FAQ
What is the minimum input voltage required for LMS3655MQRNLTQ1 to regulate a 3.3-V output at full 5.5-A load?
The LMS3655MQRNLTQ1 requires a minimum input voltage of 3.8 V to maintain full 3.3-V output regulation at 5.5-A load after startup, as specified in Section 7.7 of the datasheet. Below this, dropout behavior occurs - VOUT drops linearly with VIN, and switching frequency may fall below 330 kHz. For reliable cold-crank operation, ensure input stays ≥3.9 V under worst-case load and temperature conditions. This value is confirmed for the LMS3655MQRNLTQ1 variant with spread-spectrum enabled.
Does LMS3655MQRNLTQ1 support adjustable output voltage, and what is the valid range?
Yes, the LMS3655MQRNLTQ1 supports adjustable output voltage via the FB pin using a resistive divider. The standard adjustment range is 3.3 V to 6 V, while the extended range is 1 V to 20 V. Operation below 3.3 V or above 6 V may require schematic modifications and is not guaranteed across the full input range. For outputs >15 V, the BIAS pin must be grounded or externally powered - a requirement explicitly defined for the LMS3655MQRNLTQ1 in its recommended operating conditions.
How does the RESET output of LMS3655MQRNLTQ1 behave during enable/disable transitions?
The RESET output of LMS3655MQRNLTQ1 is open-drain and asserts low when EN is pulled low, during UVLO, or upon thermal shutdown. It releases high 3 ms after regulation is re-established, per its internal timer. Glitch filtering (24 µs) prevents false resets from noise. This behavior is identical across all LMS3655-Q1 variants including LMS3655MQRNLTQ1 and is validated per AEC-Q100 test conditions.
Is LMS3655MQRNLTQ1 pin-compatible with LMS3635-Q1 devices?
No, the LMS3655MQRNLTQ1 is not pin-compatible with LMS3635-Q1 devices despite sharing the same 22-pin VQFN package and pinout. While mechanical footprint matches, the LMS3655MQRNLTQ1 has higher current-limit thresholds (HS: 6.7–9.5 A vs. 4.5–7.5 A), different thermal derating curves, and distinct BIAS pin handling for >15-V outputs - requiring verification of layout current capacity and thermal relief. This distinction is documented in TI's Device Comparison Tables for LMS3655-Q1 and LMS3635-Q1 families.
What is the purpose of the BIAS pin on LMS3655MQRNLTQ1, and how should it be connected?
The BIAS pin on LMS3655MQRNLTQ1 powers an auxiliary regulator that improves light-load efficiency. It must be connected to the output voltage node for VOUT ≤ 15 V. For VOUT > 15 V, BIAS must be grounded or supplied by an external 3.3-V/5-V source - a hard requirement for LMS3655MQRNLTQ1 to prevent damage or regulation failure. This differs from non-adjustable variants and is specified in Section 7.3 of the official datasheet.
LMS3655MQRNLTQ1 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):
- 3.9V
- 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:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 22-VQFN-HR (5x4)
LMS3655MQRNLTQ1 FAQ
1.How can I place an order for LMS3655MQRNLTQ1 through Aetrix?
Please submit a Request for Quotation (RFQ) for LMS3655MQRNLTQ1 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 LMS3655MQRNLTQ1 reliable?
The price and inventory of LMS3655MQRNLTQ1 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LMS3655MQRNLTQ1 is usually 5 days.
3.What payment methods are accepted for LMS3655MQRNLTQ1?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LMS3655MQRNLTQ1 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LMS3655MQRNLTQ1?
LMS3655MQRNLTQ1 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LMS3655MQRNLTQ1 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 LMS3655MQRNLTQ1?
For technical support, including LMS3655MQRNLTQ1 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LMS3655MQRNLTQ1 requirements.
6.How does Aetrix verify that LMS3655MQRNLTQ1 is sourced from the original manufacturer or authorized distributors?
All LMS3655MQRNLTQ1 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 LMS3655MQRNLTQ1 meets industry standards.
7.What is the process for return or replacement of LMS3655MQRNLTQ1?
All LMS3655MQRNLTQ1 units undergo pre-shipment inspection (PSI). If there is an issue with LMS3655MQRNLTQ1, 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 LMS3655MQRNLTQ1 part is unused and in its original packaging.
Return procedure for LMS3655MQRNLTQ1:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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