Ricoh launches 30V / 2A PWM DC/DC converter with powerful methods for EMI noise reduction
Ricoh Europe (Netherlands) B.V. Semiconductor Support Centre has launched the R1275, a high-efficiency, 2A synchronous step-down DC/DC converter with a wide input voltage range up to 30V and has two options to minimize electromagnetic interference (EMI). It allows connecting to a variety of input sources, such as battery-powered portable devices, industrial supplies and automotive batteries.
There are many ways to reduce radiated and conducted EMI significantly, but few are as simple as using a Spread Spectrum Clock Generator (SSCG). The idea behind using SSCG is to modulate the clock frequency mildly, which results in spreading the EMI energy amongst many frequencies instead of concentrated at one frequency. This way, the amount of potential interference of the base frequency and its harmonics is reduced considerably.
The switching frequency is internally set to 2MHz, but it is also possible to synchronize with another DC/DC Converter by applying an external clock signal from 1.8MHz to 2.2MHz. Especially in case the power supply consists of multiple DC/DC converters, the individual switching frequencies can result in a significant noise in common ground wiring. By synchronizing all DC/DC converters to one frequency, the resulting noise is easier to filter out and will not interfere with the control of the converters.
The R1275 has a special protection for cold cranking conditions. A power supply of automotive electronic systems can be subject to a significant input voltage drop when the engine starts. To ensure that the R1275 is able to maintain its output voltage during such event, the clock signal is lowered linearly to one-fourth of the normal frequency. This will make the on-duty larger than the normal maximum duty, which reduces the voltage difference between input and output. Thus providing continuous operation in cold cranking condition.
Additional safety features include input under- and over-voltage lockout, hiccup overcurrent protection, internal soft-start circuitry, peak current limit, thermal shutdown, output over-voltage and under-voltage protection. A Power- Good pin provides a fault signal when the chip is not ready for normal operation or any of the protection circuits is active.
The R1275 is available in a thermally enhanced 5.2 x 6.2 x 1.5mm HSOP-18 package for consumer, industrial and automotive applications.
Operating Voltage 3.6V to 30V
Output Voltage Range 3.3V to 5.0V
Output Current Max. 2A
Feedback Voltage Tolerance 0.64V ±1.0%
Adjustable Oscillation Frequency 2.0MHz
External Synchronizable Clock Frequency 1.8 to 2.2MHz
Spread Spectrum Clock Generator Diffusion Rate Typ. ±8%
Adjustable Soft-start Time External Capacitor
Power Good Output NMOS Open-Drain
Safety Circuits Soft-Start, UVLO, OVLO, Thermal, UVD, OVD, Hiccup Over Current Protection
R1275 automotive version AEC-Q100 compliant
Package (5.2 x 6.2 x 1.5mm) HSOP-18
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Ricoh is a global technology company specializing in office imaging equipment, production print solutions, document management systems and IT services. Headquartered in Tokyo, Ricoh Group operates in about 200 countries and regions. In the financial year ending March 2015, Ricoh Group had worldwide sales of 2,231 billion yen (approx. 18.5 billion USD).
The majority of the company’s revenue comes from products, solutions and services that improve the interaction between people and information. Ricoh also produces award-winning digital cameras and specialized industrial products. It is known for the quality of its technology, the exceptional standard of its customer service and sustainability initiatives.
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