LM5155-Q1: LM5155-Q1 system calculator

Hi Lin,

Thank  you for considering the LM5155.  Your inputs are basically okay but there are a few problem:

1. Your min Vin is 11V.  Why set the UVLO threshold at 3V?

2. For 210V output, 100mV ripple voltage is a very tough spec. Most designs usually has 1% ripple voltage, i.e. 2.1V in your case. 

3. The entire design may not work well. Note that you need 95% duty cycle to achieve output regulation.  However, the datasheet EC-table specifies the max duty cycle may drop to 80%. 

For 11V to 200V step up ratio, we usually recommend a DCM (which is not supported by this calculator), and also two stage circuit, with the main boost plus a charge pump.  Please refer to the following ref design.  The IC is different but the concept is the same.  We are planning to releasing a LM5155 ref design for similar application, but it may take some time to show on the website.

http://www.ti.com/tool/PMP20183

If you need close design support, please contact TI sales personnel or a FAE in your region.

Thanks,

Youhao Xi, Applications Engineering.