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LMS3655NQRNLRQ1
Texas Instruments
IC REG BUCK 3.3V 5.5A 22VQFN
50996 Pcs New Original In Stock
Buck Switching Regulator IC Positive Fixed 3.3V 1 Output 5.5A 22-VFQFN
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*Quantity
Minimum 1
Minimum 1
5.0 / 5.0
- (83 Ratings)
LMS3655NQRNLRQ1
Product Overview
1345927
DiGi Electronics Part Number
LMS3655NQRNLRQ1-DGManufacturer
Texas Instruments
LMS3655NQRNLRQ1
Description
IC REG BUCK 3.3V 5.5A 22VQFNInventory
50996 Pcs New Original In Stock
Buck Switching Regulator IC Positive Fixed 3.3V 1 Output 5.5A 22-VFQFN
Quantity
Minimum 1
Minimum 1
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LMS3655NQRNLRQ1 Technical Specifications
Category
Power Management (PMIC), Voltage Regulators - DC DC Switching Regulators
Packaging
-
Series
-
Product Status
Active
Function
Step-Down
Output Configuration
Positive
Topology
Buck
Output Type
Fixed
Number of Outputs
1
Voltage - Input (Min)
3.9V
Voltage - Input (Max)
36V
Voltage - Output (Min/Fixed)
3.3V
Voltage - Output (Max)
-
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
Package / Case
22-VFQFN
Supplier Device Package
22-VQFN-HR (5x4)
Base Product Number
LMS3655
Datasheet & Documents
Manufacturer Product Page
LMS3655NQRNLRQ1 Specifications
HTML Datasheet
LMS3655NQRNLRQ1-DG
Environmental & Export Classification
RoHS Status
ROHS3 Compliant
Moisture Sensitivity Level (MSL)
2 (1 Year)
REACH Status
REACH Unaffected
ECCN
EAR99
HTSUS
8542.39.0001
Additional Information
Standard Package
3,000
Reviews
5.0/5.0-(Show up to 5 Ratings)
de desembre 02, 2025
DiGi Electronics se distingue par son efficacité logistique exceptionnelle, assurant des livraisons rapides et sans souci.
de desembre 02, 2025
迅速かつ丁寧なサポートが魅力です。価格もリーズナブルで大変満足しています。
de desembre 02, 2025
Their after-sales service shows genuine dedication to customer satisfaction.
de desembre 02, 2025
I received my order very quickly, and the support team was responsive and helpful.
de desembre 02, 2025
Their prompt and effective support reflects their professionalism.
de desembre 02, 2025
The team provided detailed guidance, making me feel valued as a customer.
de desembre 02, 2025
Their efficient logistics team ensures my orders arrive as scheduled.
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Frequently Asked Questions (FAQ)
When designing a 12V automotive ECU with the LMS3655NQRNLRQ1, what are the critical layout and thermal considerations for the wettable flank package to ensure reliable 5.5A operation in a high-temperature under-hood environment?
For the LMS3655NQRNLRQ1, the 22-VQFN-HR with wettable flanks enables automated optical inspection (AOI) but demands specific layout care. At 5.5A full load, copper dissipation is critical: use a 4-layer board with at least 2oz copper, place thermal vias under the exposed pad to inner ground planes, and ensure the pad is soldered to a continuous ground plane with >10 vias. The device lacks a synchronous rectifier, so the external Schottky diode (rated >40V, >6A) must be placed within 5mm of the SW pin to minimize ringing. For under-hood 125°C ambient, derate output current to ~4.5A without forced airflow; perform thermal simulation to keep junction below 125°C using the 26°C/W junction-to-board thermal resistance as a starting guide.
Can the LMS3655NQRNLRQ1 directly replace the LM22676 or LM2596 in an existing 24V industrial power supply design, and what PCB modifications are required to handle the higher 5.5A current and 36V input transient?
The LMS3655NQRNLRQ1 can replace LM22676 (3A) or LM2596 (3A) for higher current capability, but it is not a pin-to-pin substitute. Both older parts use TO-263 or SOIC packages, while the LMS3655NQRNLRQ1 uses a 22-VQFN-HR, requiring a new PCB layout. Key modifications: (1) Input capacitance must be increased to handle 5.5A ripple—use at least 20µF ceramic (X7R, 50V) plus a 100µF electrolytic for damping; (2) The diode must be upgraded to a >6A, 45V Schottky (e.g., Diodes Inc. PDS1045); (3) Inductor saturation current must exceed 7A; use 4.7µH to 10µH with DCR <15mΩ for efficiency. The LMS3655’s 250kHz–500kHz adjustable frequency allows optimization for size vs. efficiency, but the original PCB’s thermal dissipation area must be expanded by >50% to handle the extra 2.5W loss at full load.
When selecting the inductor for the LMS3655NQRNLRQ1 to power a 5.5A peak load in an automotive ADAS camera module, what are the trade-offs between 250kHz and 500kHz switching frequency in terms of EMI compliance and load transient response?
For the LMS3655NQRNLRQ1, choosing 250kHz minimizes switching losses (better efficiency at 5.5A) and reduces high-frequency EMI in the AM band, critical for automotive ADAS—but requires a larger inductor (~10µH, >7A sat) with higher DCR, affecting transient response. At 500kHz, you can use a smaller 4.7µH inductor (e.g., Coilcraft XAL7070-472) for better load step recovery (<50mV dip for 3A step) and smaller footprint, but you’ll see increased switching losses (~15% lower efficiency at 5.5A) and higher 500kHz harmonics that may require additional input filtering to meet CISPR 25 Class 5. For camera modules sensitive to ripple, use the 500kHz option with spread spectrum disabled and add a second-stage LC filter with a 1µH inductor and 22µF cap to reduce output ripple below 10mVpp.
How does the lack of a synchronous rectifier in the LMS3655NQRNLRQ1 affect efficiency and thermal management in a 24V-to-3.3V conversion at 5A, compared to an automotive synchronous buck like the LMR33630, and what diode selection criteria minimize the penalty?
At 24V input, 5A output, the LMS3655NQRNLRQ1’s non-synchronous topology results in about 6–8% lower efficiency than a synchronous part like LMR33630 (which integrates low-side FET), translating to ~1.2W additional dissipation at 5A. The primary loss is in the external Schottky diode. To minimize this penalty, select a diode with ultra-low forward voltage (Vf <0.4V at 5A) such as the Vishay VSSAF5L45 or Nexperia PSMN5R5-60YS, and ensure it has <50nC total charge to reduce switching losses. Place the diode with a dedicated thermal pad connected to a copper pour; at 85°C ambient, this limits the diode’s temperature rise to <45°C. The trade-off is lower quiescent current (IQ) in non-synchronous designs—LMS3655 consumes ~20µA in standby, beneficial for always-on automotive modules, whereas synchronous designs often have higher IQ due to integrated FET gate drive.
For a 3.9V input (cold-crank condition) with the LMS3655NQRNLRQ1, what is the actual maximum output current before dropout, and how does the 250kHz minimum frequency affect the duty cycle limit when powering a 3.3V rail with 5.5A peak in an automotive front camera application?
At 3.9V input, the LMS3655NQRNLRQ1 operates near dropout for a 3.3V output. The maximum duty cycle is typically 85–90% at 250kHz, so with 3.9V in, the output can regulate 3.3V only if the load current stays below 3.5–4A due to increased I²R losses in the inductor and high-side FET. At full 5.5A, the input must be >4.5V to maintain regulation. To handle cold-crank down to 3.9V, either derate output current to 3A or use the 500kHz setting—which increases the minimum off-time limit, further reducing available duty cycle, so 250kHz is actually preferred for dropout margin. For a front camera requiring 5.5A peak, add a 1000µF input capacitor to hold up voltage during the 3.9V transient and consider using a pre-boost converter to guarantee >5V input to the LMS3655NQRNLRQ1 during cold-crank events.
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