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Picor Corporation · picorpower.com

PI2211

Rev 1.1, Page 22 of 26

PI2211

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Once the max and min BUS voltage has been selected,

plugging their values into these three equations will provide

the resistance ratios of the three resistors.

Optional: Max Load Capacitance

Knowing the duration of the power pulse, the user can

calculate the available energy during start-up. Knowing this

energy, a rough calculation of the amount of load capacitance

that can be charged during the initial start-up pulse can be

calculated. This calculation takes no tolerances into account.

The energy provided to the load during an SOA pulse is:

When charging the capacitive load, the required energy peaks

at the start of the charging and reduces to zero when the

charging is complete. If the energy calculated during the SOA

pulse is considered to be the average current, then the peak

energy is twice this amount. The capacitive load can be

calculated as:

PI2211 Design Calculator

The PI2211 component calculator program is designed to calculate the required programming resistors of the PI2211 controller;

requiring the designed to enter just a few key thermal MOSFET parameters taken from the manufacturer’s datasheet. It is capable of

calculating both an under-voltage/over-voltage divider as well as a current sense divider. It can also derive a usable pulse width

available features.

Figure 18 - PICOR's Windows™ based PI2211 Design Calculator