The TPS62816-Q1 is designed for a nominal 0.22-µH inductor with a switching frequency of typically 2.25 MHz. Larger values can be used to achieve a lower inductor current ripple, but they can have a negative impact on efficiency and transient response. Smaller values than 0.22 µH cause a larger inductor current ripple, which causes larger negative inductor current in forced PWM mode at low or no output current. For a higher or lower nominal switching frequency, the inductance must be changed accordingly. See the Recommended Operating Conditions for details.

The inductor selection is affected by several effects like the following:

• Inductor ripple current
• Output ripple voltage
• PWM-to-PFM transition point
• Efficiency

In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). Equation 8 calculates the maximum inductor current.

where:

• I_L(max) is the maximum inductor current.
• ΔI_L(max) is the peak-to-peak inductor ripple current.
• Lmin is the minimum inductance at the operating point.

Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. A margin of about 20% is recommended to add. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well.