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LMR43620MSC5RPERQ1: 36V, 2A Automotive Synchronous Buck Converter
10/19/2026 1:58:53 AM
LMR43620MSC5RPERQ1: 36V, 2A Automotive Synchronous Buck Converter
1. Product Positioning
The LMR43620MSC5RPERQ1 is an automotive-qualified synchronous step-down DC/DC converter from Texas Instruments' LMR436x0-Q1 family. It drives up to 2A of load current from an input voltage as high as 36V and is housed in a 2mm × 2mm HotRod™ VQFN package. The device is designed specifically for always-on automotive and industrial applications that demand low standby power and an ultra-small solution size.
Within the family, this variant is clearly defined: 2A output current, a default output voltage of 5V (fixed or adjustable), a fixed 2.2MHz switching frequency, external synchronization capability, and spread spectrum. These parameters make it directly applicable to compact power designs that require medium power, high switching frequency, and low EMI.
2. Key Features
The most striking characteristic is the extremely low quiescent power achieved within a tiny footprint. At 13.5V input with a fixed 3.3V output, the total non-switching quiescent current is only 1.2µA; even at a light load of 1mA, efficiency remains above 85%. This enables the device to meet the stringent sleep-current limits of automotive always-on systems.
For EMI control, the LMR43620MSC5RPERQ1 employs dual random spread spectrum combined with the low parasitic inductance of the HotRod™ package and an optimized pinout to meet CISPR25 Class 5. The fixed 2.2MHz switching frequency avoids the AM broadcast band and permits the use of small inductors and capacitors, compressing the solution area. A MODE/SYNC pin supports PFM/FPWM mode selection and synchronization to an external clock, facilitating spectral management across multiple power rails.
Protection features include cycle-by-cycle current limit, a PGOOD indicator with delay, precision EN/UVLO, and thermal shutdown. The operating junction temperature range is −40°C to +150°C, with support for 42V automotive load dump and operation down to 3V input during cold crank.
3. Key Specifications
| Parameter | Specification |
|---|---|
| Input Voltage Range | 3.0V to 36V (42V transient) |
| Output Current | 2A |
| Output Voltage | 5V fixed / adjustable (this variant defaults to 5V) |
| Switching Frequency | Fixed 2.2MHz |
| Quiescent Current (non-switching) | 1.2µA (13.5VIN, 3.3VOUT) |
| Efficiency at 1mA | Greater than 85% |
| External Synchronization | Yes (PFM/FPWM selectable) |
| Spread Spectrum | Yes |
| Package | 2mm × 2mm VQFN-HR (HotRod™) |
| Junction Temperature | −40°C to +150°C |
| Automotive Qualification | AEC-Q100 Grade 1 |
4. Questions and Answers
Q: What is the default output voltage of the LMR43620MSC5RPERQ1? Can it be adjusted?
A: This variant defaults to a fixed 5V output. Using an external feedback resistor divider, the output can also be adjusted from 1V to as high as 95% of VIN. If a fixed 3.3V output is required, the LMR43620MSC3RPERQ1 in the same family is the more direct choice.
Q: What are the practical benefits of a fixed 2.2MHz switching frequency?
A: A 2.2MHz frequency lies above the AM broadcast band, avoiding interference with automotive radios. At the same time, the high switching frequency permits smaller inductors and output capacitors, enabling an extremely compact layout around the 2mm × 2mm package. The trade-off is somewhat higher switching loss, but the device's low quiescent current at light load compensates for this.
Q: What does a 1.2µA quiescent current mean in a real system?
A: For automotive modules permanently connected to the battery, quiescent current directly determines battery drain while the vehicle is parked. A non-switching quiescent current of 1.2µA means that, on a 12V battery, simply maintaining the regulator in standby would theoretically take roughly 100 years to consume 1Ah of capacity. This makes it suitable for radar ECUs, body control, telematics, and other loads that must remain on for extended periods.
Q: How does the HotRod™ package help with EMI and thermal performance?
A: The HotRod™ package eliminates conventional bond wires, using flip-chip or copper pillar interconnects to significantly reduce parasitic inductance. This lowers high-frequency ringing at the switch node, reducing radiated EMI at the source. The low parasitics also improve efficiency and thermal performance, making 2A output possible within a 2mm × 2mm footprint.
5. Typical Applications
The primary application space is concentrated in automotive electronics and industrial systems. On the automotive side, it serves radar ECUs in advanced driver assistance systems, body electronics and lighting modules, pre-regulation for infotainment systems, and sensor supplies requiring CISPR25 Class 5 compliance. On the industrial side, field transmitters, thermostats, and servo drive position sensors - where space is constrained and low standby power is essential - are equally relevant targets. Its 3V cold-crank capability and 42V load-dump tolerance allow it to connect directly to the automotive battery rail without additional pre-boost or clamping circuitry.
6. Conclusion
The LMR43620MSC5RPERQ1's value lies in integrating 36V tolerance, 2A output, a fixed 2.2MHz frequency, ultra-low quiescent current, and CISPR25 Class 5-level low EMI performance into a 2mm × 2mm package. For automotive and industrial designs that require reliable, low-standby, low-emission step-down conversion within an extremely small area, it is a closely matched specification choice.
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