Graphics Chip Supply Delivers 1.65V at 26A

Game boxes are using more powerful processors to provide more realistic and complex graphics and games. As the processor power increases, so does the current required to power the parts. The MAX1954 in the application pictured below delivers 1.65V @ 26A from a 5V input.

The MAX1954 is a 300kHz current-mode step-down controller. The MOSFET drivers are strong enough to handle 100nC gate charge. Given the nominal input and output voltages, the duty cycle is 33 and the on-resistance of the high- and low-side FETs are skewed accordingly. Two IRF7811W with 12m on-resistance each are used for the high-side and two IRF7822 with 6.5m on-resistance each are used for the low-side. Two IRF7811W in parallel have better switching characteristics than one IRF7822.