For a setup involving the IR2101SPBF MOSFET driver from Infineon Technologies, when you're considering a diode between the VCC and VB pins (pins 1 and 8, respectively), the purpose is typically to ensure smooth charge flow to the high side gate driver circuit. This is usually aimed at situations where the high side MOSFET is being driven in a half-bridge configuration, ensuring that the bootstrap capacitor can recharge properly.

Given this context, the key characteristics for the diode would include:

A common choice is a fast or ultrafast recovery diode. Assuming a general-purpose application with a supply voltage (VCC) up to 15V, which is typical for such drivers, and anticipating the need for a safety margin, I'm recommending a diode with the following assumed parameters:

Based on these assumptions, a diode like the 1N5819 could be a suitable choice. It's a Schottky diode, which inherently has a low forward voltage drop and a quick reverse recovery time, making it efficient for this purpose.

Here's how you would connect it in your schematic in Flux:

This connection will allow the bootstrap capacitor (which should be connected between U1:VB (Pin 8) and U1:VS (Pin 6)) to recharge via VCC during the off cycles of the high side switch.

Keep in mind, the specific requirements of your project could necessitate adjustments to these recommendations. If your application operates at a significantly higher voltage or current, or if other specific conditions apply, you should consider diodes that more closely match your needs.

what about 1N4148 ?

The 1N4148 is a widely used, general-purpose switching diode known for its fast switching speeds (reverse recovery time is typically around 4 ns). However, it has specific characteristics that may or may not make it suitable for use between the VCC and VB pins of the IR2101SPBF driver, depending on the specific requirements of your application. Here's a brief evaluation considering its standard specifications:

Given these points, the critical consideration when thinking about using the 1N4148 in a bootstrap circuit for the IR2101SPBF would be the forward current requirement. If your circuit operates at relatively low currents and the charging current requirement for the bootstrap capacitor is well within the 300mA limit, the 1N4148 could be technically used due to its fast switching characteristics. However, its relatively low forward current rating compared to power diodes designed for handling higher currents makes it less ideal for higher power applications.

Here are the assumptions under which the 1N4148 could be appropriate:

If you decide to use the 1N4148, here's how you would connect it:

Please review the specifics of your application, particularly the expected high-side gate driving current and the switching frequency, to ensure the 1N4148 will meet your needs without being pushed beyond its ratings. For higher current applications, a Schottky diode like the 1N5819, or another diode with a higher forward current rating, might be more appropriate.