7.3.6 Output Stage

The DRV5021-Q1 output stage uses an open-drain NMOS transistor that is rated to sink up to 20 mA of current. For proper operation, calculate the value of pullup resistor R1 using Equation 1.

Equation 1.

The size of R1 is a tradeoff between the OUT rise time and the current when OUT is pulled low. A lower current is generally better; however, faster transitions and bandwidth require a smaller resistor for faster switching.

In addition, the value of R1 must be > 500 Ω in order to make sure that the output driver can pull the OUT pin close to GND.

Figure 19. Open-Drain Output

Select a value for C2 based on the system bandwidth specifications shown in Equation 2.

Equation 2.

Most applications do not require this C2 filtering capacitor.