The Japanese Origin Electric is a well-known manufacturer of high-voltage semiconductor devices in the Japanese market. Its featured model MD8CP5 (8KV 500MA 75NS) is very common in Japanese high-voltage X-ray generators, such as Shimadzu X-ray machines. Some high-voltage X-ray machine manufacturers in China and Europe also use this rectifier diode in their high-voltage multiplier modules. MD8CP5 (8kV/500mA), MD15EP06 (15kV/60mA), and MD15FP3 (15kV/300mA) are the main models promoted by Origin Corporation in the medical Xray equipment market. In the spring of 2023, Origin Corporation suddenly announced the discontinuation of the MD8CP5 part number and shifted to producing silicon stacks with higher voltage and current. Many European and Asian customers need to find suitable replacements, and HVC Company’s HVD-SL513G (8kV/500mA, 50ns) high-voltage diode can perfectly replace MD8CP5.
 
Model history:
MD8CP5 (8kV/500mA). This high-voltage diode is used in medical X-ray machines and DR (Digital radiography). It was first introduced over 20 years ago by the well-known Japanese company Sanken Electric in their UX-FOB (8kV/500mA 50ns), which is a rectangular prism measuring 7x7x21mm. This model was very popular and widely used in the high-voltage circuit boards of many medical X-ray machine manufacturers in Europe, America, and Japan. In 2003, the American company HVCA introduced a competing product with the same model number, UX-FOB, which is also 7x7x22mm in size. Due to the continuous improvement and miniaturization of semiconductor production processes, Origin Corporation in Japan introduced a replacement product of the same specifications, with a cylindrical plastic outer shape measuring 4.4x7.6mm in diameter. This model has been adopted by many well-known X-ray machine manufacturers in Japan, such as Shimadzu, who invented Japan’s first X-ray machine. MD8CP5 has also been promoted by Japanese-German agents to some important medical X-ray machine brands in Asia and Europe.
 
Technical challenges and reasons for replacement failure:
MD8CP5, or its prototype UX-FOB, is used in medical X-ray machines, which require high-voltage and high-frequency circuits with a working frequency of generally 50-100kHz. This requires the rectifier diode in the multiplier circuit to withstand high frequency and achieve ultrafast recovery time, which is generally required to be in the range of 40ns to 60ns. In addition, it needs to maintain this ultrafast recovery time when working under high voltage, which is the technical challenge of this product. At the same time, due to the frequent occurrence of pulse phenomena in such high-voltage multiplier circuits, the margin of the diode design must be high enough. Assuming the rated voltage of the diode is 8KV and the actual input voltage is 6KV, the reserved pulse requires a working voltage of 2.7 times, which is 16.2KV. This requires the diode’s factory test standard to reach a level of 16KV. According to the author’s actual measurement, the maximum withstand voltage level of MD8CP5 and UX-FOB is about 10KV. This means that if the voltage margin of the competing brand is not large enough, or the recovery time is not fast enough, and the diode needs to achieve both high current and fast recovery characteristics, this is already a significant challenge, and the performance of the diode in the circuit cannot be equivalent to that of the original UX-FOB. This is not an easy replacement project, and many competing brands with the same model number cannot be recognized by end customers.
 
Reasons for the successful replacement of HVD-SL513G:
HVC’s HVD-SL513G (improved version HVD-SL516G) was introduced in 2018 to complement HVC’s high-voltage capacitors with high-voltage diodes. It is a main replacement model for the US and Japanese UX-FOB and Origin Corporation’s MD8CP5. As mentioned earlier, HVC not only considered the actual parameters of competing models but also the actual needs of high-voltage multiplier circuits in medical device end customers (such as pulses and high-frequency environments). They made significant adjustments to the frequency and ultra-fast recovery time of the diode, and ultimately successfully replaced UX-FOB and obtained end-customer recognition as well as inspection and certification from a well-known power company in Europe and Japanese customers.
 
Frequently matching high voltage ceramic capacitors：
Common high-voltage ceramic capacitors used with high-voltage multiplier circuits in DR equipment are the popular diode model UX-FOB and the popular high-voltage capacitor model DHR4E4C102K2FB (15KV 1000pf, B) from Murata Corporation. This capacitor model can be found in many high-voltage X-ray machines. In the spring of 2018, Murata announced its withdrawal from the high-voltage ceramic capacitor market, and HVC introduced the HVC-15KV-DL18-F12.5-102K as a pin-to-pin replacement, which obtained testing and certification from many different categories of X-ray machine manufacturers.
 
Below are other discontinued high-voltage rectifier diode models from ORIGIN Corporation. HVC provides corresponding replacement models for each of them. If end customers need to replace ORIGIN’s high-current ultra-high-voltage silicon stack diodes, our company can also customize replacement products.