How to control EMI at an extremely low level? This voltage regulator can help
Automotive, transportation, and industrial applications are noise sensitive and require low EMI power solutions. Traditional approaches control EMI by slowing down switching edges or reducing switching frequency. Both approaches have undesirable effects such as reduced efficiency, increased minimum on and off times, and the need for larger solution sizes. Alternatives such as EMI filters or metal shielding add significant costs in required board space, components, and assembly, and complicate thermal management and testing.
Low-noise Silent Switcher architecture simplifies EMI design
ADI's low noise μModule technology brings a breakthrough in switching regulator design. The LTM8003 regulator in a μModule package features a proprietary Silent Switcher architecture to minimize EMI emissions and provide high efficiency at high switching frequencies. The architecture of the regulator and the internal layout of the μModule device are designed to minimize the input loop of the regulator. This can significantly reduce switch node ringing and the associated energy stored in the hot loop, even in the presence of very fast switching edges. This quiet switching provides excellent EMI performance while minimizing AC switching losses, allowing the regulator to operate at high switching frequencies without significant loss in efficiency.
This architecture, coupled with spread spectrum frequency operation, greatly simplifies EMI filter design and layout, making it ideal for noise-sensitive environments. Figure 1 shows a simple EMI filter on the input side, allowing the demonstration circuit to pass the CISPR 25 Class 5 standard with sufficient margin, as shown in Figure 2.
Figure 1. A 5 V converter with a simple EMI filter on the input meets CISPR 25 Class 5 specifications.
Figure 2. The DC2416A demonstration circuit meets the CISPR 25 Class 5 specification for radiated EMI spectrum.
3.5A continuous current and 6A peak current capability
The internal regulator can safely deliver up to 6 A of peak output current, and the LTM8003 does not require additional thermal management measures (airflow or heat sink) when continuously supporting a 3.5 A load (in the 3.3 V or 5 V range) from a 12 V nominal input. This meets the needs of battery-powered applications in industrial robots, factory automation, and automotive systems.
Wide operating temperature range from –40°C to +150°C
Automotive and industrial applications require power circuits to operate continuously and safely in ambient temperatures exceeding 105°C, or require a large reserve space for temperature rise. The LTM8003H is designed to meet specifications over an internal operating temperature range of –40°C to +150°C. An internal over-temperature protection (OTP) circuit monitors the junction temperature and stops switching when the junction temperature is too high.
Figure 3a shows a 3.5 A, 5 V solution that operates over a wide input range of 7 V to 40 V. Its thermal performance at a nominal 12 V input is shown in Figure 3b. With a 12 V input and a 2 A load, the typical efficiency is above 92%.
Figure 3. A 5 V, 3.5 A solution for 7 V to 40 V input in the H-grade version. Thermal imaging shows that no bulky heat sink components are required.
Generates –5 V negative output from +3.5 V to +35 V input
Figure 4 shows a solution for generating a –5 V, 4 A output from a 12 V nominal input (35 V maximum input). The BIAS pin should be connected to GND.
Figure 4. A –5 V supply delivers up to 4 A of output current from a +5 V to +35 V input.
in conclusion
The LTM8003 is a wide input and output range, low noise, 3.5 A step-down µModule regulator using Silent Switcher architecture. It can generate 0.97 V to 18 V output from a 3.4 V to 40 V input, eliminating the need for intermediate regulation from a battery or industrial power supply. Its pinout is specifically designed to meet FMEA (Failure Mode Effect Analysis) requirements, so if adjacent pins are shorted, a single pin is shorted to ground, or some pins are floating, the output voltage will remain at or below the regulation voltage. Redundant pins enhance electrical connections in cases where solder joints become loose or open due to vibration, aging, or wide temperature variations (for example: in automotive and transportation applications).
Figure 5. A complete step-down solution is only slightly larger than the 6.25 mm x 9 mm footprint of the LTM8003 µModule regulator.
The complete solution fits in a compact footprint that is not much larger than the LTM8003’s 6.25 mm × 9 mm × 3.32 mm BGA package (including input and output capacitors). Typical 25 µA quiescent current and a wide operating temperature range of –40°C to +150°C (H-grade) make it ideal for environments where space is tight, operating environments are harsh, and low quiescent current and high reliability are mandatory. The device’s features help minimize design effort and meet stringent standards for industrial robotics, factory automation, avionics, and automotive systems.
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