用 an op-amp and power transistor设计power regulator？

This bus voltage is then regulated down using a standard
textbook-design programmable power regulator containing an op-amp and power
transistor. The regulator produces a stable output of between 20 and 49.4 volts.
怎么用 an op-amp 和 power transistor 设计 输入+60V，输出 20-50V的 regulator?

search LDO or linear regulator.

....随便哪本模电教材里不都有吗？
或者找个ldo的datasheet看结构框图也行啊

你还是找人做吧，省点时间搞主业