Power and Converters

Bus Overvoltage Protection:

• 60V TVS diode(s):

Gate Driver Buck (LMR160006):

Feedback:

R2 = 18k, R1 = 100k, Vout = 5V

• https://www.digikey.ca/en/products/detail/yageo/RC0603FR-0718KL/726989

• https://www.digikey.ca/en/products/detail/yageo/RC0603FR-07100KL/726889

Inductor:

Using Vin,max = 50.4V, Vout = 5V, fsw = 700kHz, Io = 100mA, K = 0.3, we find that our inductor must be at least 214uH with a continuous current rating of at least 200mA. Will results in 40mA ripple current. From here we optimize filters such as DCR, size, cost, and self-resonant frequency.

Note: We want a K (ratio of ripple current to output current) to be around 0.3. A higher output current will result in a higher ripple current which will cause things like higher ripple voltage, more EMI, and be less efficient. An acceptable ratio is 0.3. If you would like to lower that ratio and decrease you ripple current a larger inductance in needed, but as long as you have a ratio of around 0.3 you’re chilling in CCM with a relatively stable output rail.

• https://www.digikey.ca/en/products/detail/laird-signal-integrity-products/TYS6045221M-10/4733499

Schottky Diode:

• Voltage rating of at least 1.25x max input = 50.4*1.25 = 63V. Current rating of at least 200mA

• https://www.digikey.ca/en/products/detail/smc-diode-solutions/DSS18U/8341862

Output Capacitance:

• Delta I_out is 0.1A, fsw = 700kHz, and desired delta V_out is 0.01V. Minimum voltage rating is 5V. This gives a minimum values of 29uF. Accounting for DC bias, we will use 3 of the following 47uF capacitor for output capacitance (DC bias: 15uF @ 5V)

• https://www.digikey.ca/en/products/detail/murata-electronics/GRM21BR61A476ME15L/4905529

Input Capacitance:

• Max output current is 100mA, input, fws = 700kHz, desired input ripple is 0.01V. This gives a minimum value of 3.6uF. Minimum voltage rating is 60V. We will go with 10uF. Accounting for DC bias, we will get put 3.

• https://www.digikey.ca/en/products/detail/murata-electronics/GRM32EC72A106KE05L/7319245

5V to 3V3 LDO:

• 3V3 fixed output, 300mA current rating is plenty, max input voltage is 18V, $0.48 pog

• https://www.digikey.ca/en/products/detail/diodes-incorporated/AP7370-33WW-7/10295009

  • One 10uF 25V for input and one for output

  • https://www.digikey.ca/en/products/detail/murata-electronics/GRM188R61E106KA73J/9887674