LMS3655LQRNLRQ1 - 5.5A 36V Sync Step-Down Converter | TI
MPN: LMS3655LQRNLRQ1 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.08 | $4.08 |
| 10 | $3.67 | $36.70 |
| 100 | $3.26 | $326.00 |
| 500 | $2.94 | $1,470.00 |
| 1,000 | $2.61 | $2,610.00 |
| 3,000 | $2.2 | $6,600.00 |
LMS3655LQRNLRQ1 Overview
A buck converter (step-down switching regulator) is a switched-mode power supply topology that uses an inductor, a high-side switch, and a synchronous low-side switch to efficiently convert a higher DC input voltage to a lower DC output voltage. Buck regulators dominate point-of-load conversion because they deliver far higher efficiency than linear regulators when the input-to-output voltage differential is significant, and they belong to the broader DC-DC switching regulator family inside power management ICs.
Key specifications include a 5.5 A continuous output current, 36 V maximum input, 400 kHz switching frequency, fixed 5 V output (with 3.3 V and adjustable 1 V to 20 V variants in the same family), and seamless PWM-to-PFM transition that holds efficiency high at light load. The integrated MOSFETs and 400 kHz frequency enable a compact LC filter, while advanced high-speed control loop provides superior transient response for digital loads such as SoCs and FPGAs.
The LMS3655-Q1 uses TI's advanced high-speed control architecture with internal synchronous MOSFETs to minimize external component count and PCB area. The PWM/PFM auto-transition maintains efficiency across load current, and the low quiescent current extends standby time in always-on subsystems. The PowerVQFN-22 package provides low thermal resistance for continuous 5.5 A delivery.
Typical applications include automotive infotainment and ADAS power rails, industrial 24 V bus point-of-load conversion, body electronics and lighting controllers, and battery-powered equipment needing high step-down efficiency. Its wide 3.5 V to 36 V input supports load-dump-tolerant automotive supplies as well as 24 V industrial rails.
When designing, place input bulk capacitance close to VIN/PGND, minimize the high-di/dt loop area, and use a 2-layer PCB inner ground pour under the PowerVQFN thermal pad. Follow the LMS3655-Q1 datasheet layout example for the smallest EMI footprint.
This page combines distributor pricing, drop-in same-package alternatives, and design notes not aggregated on the manufacturer product page.
Drop-in alternatives for LMS3655LQRNLRQ1 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
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LMS3655LQRNLRQ1 Maximum Ratings & Electrical Characteristics
| Topology | Synchronous Buck (Step-Down) |
| Input Voltage Range | 3.5 V to 36 V |
| Maximum Input Voltage | 36 V |
| Output Voltage | 5 V (fixed) |
| Continuous Output Current | 5.5 A |
| Switching Frequency | 400 kHz (typ) |
| Operating Temperature Range | -40 C to +125 C (AEC-Q100) |
| Package | 22-pin PowerVQFN (RNL) |
| Mounting Type | Surface Mount |
| AEC-Q100 Qualification | Qualified (Q1 suffix) |
| RoHS Status | Compliant |
| Lead-Free | Yes |
LMS3655LQRNLRQ1 Pin Configuration
| Pin 1 | AGND — Analog ground |
| Pin 2 | FB — Feedback (5 V sense) |
| Pin 3 | RT/SS — Frequency / soft-start |
| Pin 4 | COMP — Compensation node |
| Pin 5 | EN — Enable (active high) |
| Pin 6 | PG — Power good indicator |
| Pin 7 | VIN — Input supply |
| Pin 8 | VIN — Input supply |
| Pin 9 | VIN — Input supply |
| Pin 10 | PGND — Power ground |
| Pin 11 | PGND — Power ground |
| Pin 12 | PGND — Power ground |
| Pin 13 | SW — Switch node |
| Pin 14 | SW — Switch node |
| Pin 15 | SW — Switch node |
| Pin 16 | SW — Switch node |
| Pin 17 | SW — Switch node |
| Pin 18 | BST — Bootstrap for HS driver |
| Pin 19 | PGND — Power ground |
| Pin 20 | VIN — Input supply |
| Pin 21 | PGND — Power ground |
| Pin 22 | PAD — Thermal pad (must be soldered to PGND) |
Typical Applications
LMS3655LQRNLRQ1 is suitable for 6 applications: Automotive Infotainment Power Rail, ADAS Sensor Power (Radar / Camera), Industrial 24 V Bus Point-of-Load, Body Electronics & Lighting ECU, Battery-Powered Portable Equipment, Server & Telecom 12 V POL.
Automotive Infotainment Power Rail
The LMS3655LQRNLRQ1 delivers a clean 5 V at 5.5 A for infotainment head units, cluster displays, and telematics modules. Its 36 V input withstands 24 V automotive load-dump transients without external clamping, and the AEC-Q100 grade guarantees operation from -40 C to +125 C. The 400 kHz switching keeps the LC network compact under the head-unit chassis. Unlike an LDO, the synchronous buck holds >90% efficiency at 5.5 A, eliminating heatsinking for the main SoC rail.
Recommended
ADAS Sensor Power (Radar / Camera)
The LMS3655LQRNLRQ1's low output ripple and fast transient response suit ADAS radar and camera modules that draw pulsed loads up to 5.5 A. The fixed 5 V output feeds SoC cores and serializer supplies with sub-1% ripple, critical for noise-sensitive RF front ends. AEC-Q100 qualification plus the wide 3.5 V to 36 V input survive cold-crank and load-dump events. The 400 kHz frequency stays outside the 24 GHz radar band, reducing EMI coupling.
Recommended
Industrial 24 V Bus Point-of-Load
On industrial 24 V factory bus rails, the LMS3655LQRNLRQ1 converts down to 5 V at 5.5 A for PLCs, motor controllers, and HMI displays. The 36 V input tolerates common-mode transients on long cable runs, and the AEC-Q100 grade provides extra margin for harsh industrial environments. Synchronous rectification and PWM/PFM auto-transition hold efficiency above 85% across the load range, reducing thermal stress in sealed enclosures.
Recommended
Body Electronics & Lighting ECU
The LMS3655LQRNLRQ1 powers body control modules and LED drivers from the 12 V automotive battery with up to 5.5 A capacity. Its wide 3.5 V to 36 V input covers cold-crank down to 6 V (with boost hold-up) and load-dump up to 36 V. AEC-Q100 Grade 1 certification and the PowerVQFN-22 thermal pad handle continuous high-current delivery in the small body-ECU footprint. The 5 V fixed output simplifies routing to MCUs and CAN transceivers.
Recommended
Battery-Powered Portable Equipment
The LMS3655LQRNLRQ1's low-IQ PWM/PFM auto-transition extends runtime in battery-powered industrial handhelds and portable diagnostics. Even at light loads, the synchronous buck maintains high efficiency, drawing only microamps of quiescent current when in PFM. The wide input range accepts multi-cell Li-Ion packs (up to 36 V transient), and the PowerVQFN-22 fits dense handheld layouts. Output is a clean 5 V for USB-PD and sensor subsystems.
Recommended
Server & Telecom 12 V POL
In 12 V server and telecom point-of-load applications, the LMS3655LQRNLRQ1 delivers 5 V at 5.5 A for memory, fan controllers, and housekeeping MCUs. Although the 36 V rating is over-spec for 12 V buses, it provides margin for hot-swap transients and protects downstream logic. Synchronous rectification plus 400 kHz switching enable a compact LC filter, fitting 1U/2U server form factors while staying below AM-band EMI.
Recommended
Recommended Products Summary
Engineering reference data for LMS3655LQRNLRQ1 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | LMS3655LQRNLTQ1 | LMS3655MQRNLRQ1 | LMS3635LQRNLRQ1 |
|---|---|---|---|---|
| Package | 22-pin PowerVQFN (RNL) | 22-pin PowerVQFN (RNL) - same | 22-pin PowerVQFN (RNL) - same | 22-pin PowerVQFN (RNL) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Input Voltage (max) | 36 V | 36 V | 36 V | 36 V |
| Output Voltage | 5 V (fixed) | 5 V (fixed) | 5 V (fixed) | 3.3 V (fixed) |
| Output Current | 5.5 A | 5.5 A | 5.5 A | 3.5 A |
| Switching Frequency | 400 kHz | 400 kHz | 400 kHz | 400 kHz |
| AEC-Q100 | Qualified (Grade 1) | Qualified (Grade 1) | Qualified (Grade 1) | Qualified (Grade 1) |
Key Differentiators
- 5.5 A vs 3.5 A in same footprint (vs LMS3635LQRNLRQ1)
- Synchronous rectification with PWM/PFM auto-transition (vs LMR33630ADDAR)
- AEC-Q100 Grade 1 with 36 V load-dump margin (vs LMR23630FQDRRRQ1)
Design Notes
Estimated: With 5 V output at 5.5 A, peak efficiency typically 92-94% at VIN=12 V means ~2 W dissipation in the PowerVQFN-22 package (theta_JA ~30 C/W on a 4-layer board), giving ~60 C rise above 25 C ambient. Use a 4-layer board with the exposed thermal pad soldered to a 1-2 sq inch copper pour for safe continuous operation.
Minimize the high-di/dt loop containing input capacitor, high-side MOSFET, low-side MOSFET, and PGND. Place input bulk and ceramic capacitors as close as possible to the VIN/PGND pins. Keep the SW node traces short and away from FB and AGND to avoid noise coupling that degrades output ripple.
Do not exceed the 36 V absolute-maximum VIN rating even during load-dump transients - add a TVS clamp if the upstream battery trace is long. Tie EN to VIN through a 100 kohm resistor if enable sequencing is unused. Ensure the BST capacitor is placed within 1.5 mm of the BST pin for proper high-side drive.
Compliance Information
AEC-Q100 Grade 1 per Q1 suffix. RoHS and REACH compliant per TI product page. Halogen-free status not stated in verified data.
