Alessandro Giuseppe Antonio Anastasio Volta and André-Marie Ampère never imagined it, but currently, the highly technical world can no longer function without voltage and electricity.
Pretty much everything would collapse without an electrical power supply. From simple consumer devices to LED lighting, computer networks, a medical device that helps people stay healthy, satellites, or the Hubble telescope that we use to explore distant worlds. And then there are the navis and the electric vehicles.
Electric vehicles
Currently, ships would find it difficult to reach their port of destination without satnavs, and airplanes would need an additional navigator. And what about "e-mobility"? Electric vehicles have to be safe and they are even supposed to drive autonomously! The car is being rethought. There is no longer a steering wheel.
And RECOM sits in the back seat. Three on-board computers, countless sensors, endless software, artificial intelligence! When everything works together and is sufficiently developed, it will rely on the technology, pull down the blinds, and arrive relaxed. Fine, it still has a bit of a future, but it already exists for vehicles for the disabled.
Reliability
They have to work just as safely and reliably as the entire computer technology
The big fat traction battery powers the engine. All the other consumers, such as the onboard computers with their AI programs, are also powered by the traction battery, but they need lower voltages, such as 12V, 18V, 24V, and so on.
The actual microcontrollers and their peripherals work with 5V, 3.3V, or 1.8V and these are again derived from the 12V. RECOM has already arrived at the first hard requirement for DC/DC converters. They have to work just as safely and reliably as the entire computer technology.
Component technology
And unfortunately, for physical law reasons, they also get warm. And whenever something gets warm (possibly hot), there is aging. At low temperature increases this is insignificant, but the hotter the components get, the more aging processes set in. In the case of electrolytic capacitors, even disproportionately.
With the existing component technology, only good heat dissipation can help. Fans are usually out of the question, so the only way to dissipate heat is via heat-conducting material, such as a base plate made of aluminum, which transfers the heat directly to the enclosure.
Advantages of converters
From a 12V rail, an internal supply bus so to speak, 3.3V is generated directly at the microcontroller
And then there is a second "trick": instead of using one large DC/DC converter, several small converters are distributed over a large area (distributed power architecture). This also has the advantage that the voltages are generated where they are needed.
From a 12V rail, an internal supply bus so to speak, 3.3V is generated directly at the microcontroller, and the analog circuit for processing the sensor signals receives its own 12V/5V converter in its immediate vicinity. This architecture is also known as PoL (Point of Load). In addition to distributed heat, it also has EMC advantages.
Size and EMC
Based on what has been said so far, we can already see that the importance of small, highly efficient DC/DC converters is increasing and determining the architecture of a device.
In addition to the requirements already mentioned, the converters must have the smallest possible dimensions, and provide a highly constant and accurate output voltage that remains within defined limits even when the load jumps. They must have a wide input voltage range and also be very cost-effective.
Requirements
Switching regulators require EMC-compliant filtering at the output and sometimes also at the input
In most cases, the requirements can practically only be realized with switching regulators, because a series regulator would generate too much waste heat.
However, switching regulators require EMC-compliant filtering at the output and sometimes also at the input. When selecting a converter, it is therefore important to consider which standards it already fulfills and which additional filters are required.
Converter range
Converters commonly available on the market range in power from a few hundred milliwatts to several hundred watts. As different as the power ratings are, so are the common designs.
These range from SMD, SIL, or DIL for the power range up to approx. 10W, to the inch sizes for powers up to approx. 40W, to the brick converters for high power. A so-called full brick measures 117mm x 61mm.
An example
RPX-4.0, a miniature step-down converter in a thermally optimized QFN package with an extremely high power density
To give an example of a switching voltage regulator, we deliberately choose a low-power converter, because high efficiency and high power density are particularly difficult to achieve with small converters. It is the RPX-4.0, a miniature step-down converter in a thermally optimized QFN package with an extremely high power density.
It weighs only 2g, making it particularly suitable for weight-constrained applications such as flying drones, acceleration circuits, and portable devices. At 5V output voltage, the power density is 180W/cm3!
- Wide input voltage range
The wide input voltage range covers all common battery voltages. Therefore, it can be used in practically all battery-powered products.
The useful CTRL input can be used to put the RPX-4.0 into sleep mode or to switch a high-output current with a low-power control signal. It can also be used very easily for an emergency stop function.
- RPX.4.0
The RPX-4.0 is designed for 3.8 to 36V input voltage and delivers - adjustable with two resistors
It is unusual for such a small device, the RPX.4.0 can supply up to 4 amps, sufficient for stepper motor drivers, high starting current applications, or laser power supplies.
The RPX-4.0 is designed for 3.8 to 36V input voltage and delivers, adjustable with two resistors - 1 to 7V output voltage with 4A. With its compact dimensions of 5mm x 5.5mm and a height of only 4.1mm, the step-down converter module sets new standards in power density. The RPX-4.0 is fully protected against Undervoltage, short circuits, overcurrent, and overheating.
Efficiency
Figure 1: Efficiency vs Load RPX-4.0 (Vout = 5VDC, Tamb = 25°C)
The high efficiency of the RPX-4.0 allows operation at full power up to 65°C and with power reduction up to 90°C depending on the variant and mounting arrangement.
The efficiency curve rises for low output powers, i.e. the converter can also be used advantageously for medium and low output powers. This is achieved, among other things, by intelligent control of the switching frequency and an integrated and shielded storage choke, which additionally ensures low EMI.
- 3-year RECOM warranty
An RPX-4.0-EVM-1 evaluation board is also available to allow customers to test all product features
The design follows RECOM's '3D Power Packaging®' technology for high power density and uses a flip-chip on leadframe construction. It comes with a 3-year RECOM warranty.
An RPX-4.0-EVM-1 evaluation board is also available to allow customers to test all product features and optimize filtering to meet target system requirements.
Lossless power source
If LEDs are fed from a voltage source, they require a series resistor for current limitation and operating point adjustment. Significant power loss is generated in it. It can be avoided if a current source is used to power the LED.
With a voltage regulator and an operational amplifier, a simple circuit can be realized that has the current source characteristic concerning the LED:
Figure 2: Current Source Application Example
Figure 3: Output characteristic curve
Size comparison
With RECOM's 3DPP® technology, the RPX-4.0 has a significantly higher power density than conventional converters, as shown in these comparative images, all at the same scale.
Despite its incredibly small size, the excellent internal thermal management design still allows full load operation without forced cooling.
