recommended solution of DCDC converter Vin:-15V, Vout:;5V, Iout=1A

Hi Ryuji,

For -15V to 5V/1A, take a look at PMP4742 http://www.ti.com/tool/PMP4742?keyMatch=null&tisearch=tidesigns-power  There are several circuits on this design, but the TPS40210 plus TL431A is a way to boost a -12V input to a 12V output. This is the architecture that you would need.

For -15V to -90V/10mA, you can use a boost architecture like shown in PMP4589 http://www.ti.com/tool/PMP4589 and leverage a doubler or tripler like shown in PMP8956 http://www.ti.com/tool/PMP8956?keyMatch=null&tisearch=tidesigns-power The doubler or tripler will help lower the duty cycle of the boost.

Ryan