Toyoki Taguchi

10A 12V 1 chip digitally-controlled DC/DC converter IC with high resolution and high frequency DPWM

This paper introduces a 10 A 12 V single chip digitally-controlled DC/DC converter IC based on the low cost 0.6 um BiCD process. This IC includes the digital pulse width modulator (DPWM) module with the dead-time programmability. The average time resolution is 1.22 ns at the clock frequency 25 MHz on 0.6 um process. This resolution is as same as that for the counter-based DPWM with the clock frequency 817 MHz. The chip adopted low impedance metal bump technology for reducing a parasitic interconnection resistance in the power stage. The fabricated chip achieves a low on resistance 9.7 mOmega in the 20 V output LDMOS (@drain current=5 A, gate voltage=5 V). The maximum efficiency is 86.4% at output current 5 A when the input voltage, the output voltage and switching frequency and the dead-time are 12 V, 1.3 V, 780 KHz and 15 ns, respectively. The maximum voltage deviation and transient response time are 42 mV and 8 us, respectively in step-load (5 A to 10 A) transient response.

High-density overwrite recording for a phase-change medium using a visible-light laser diode

A fast data transfer and high density recording was realized, using a 30 mw visible laser and a GeTeSb phase-change medium. Fast laser power control technique was used for suppressing the laser light power fluctuations, and a RIN of -123 dB was obtained. Using this technique, a CNR of 56 dB and an erase ratio of 25 dB was obtained with a mark pitch of 1.25 micrometers for an overwritable phase change medium.