SLVSFS6A May 2021 – September 2021 TPS629210-Q1
ADVANCE INFORMATION
The TPS629210-Q1 is designed for a nominal 2.2-µH inductor. 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 2.2 µH will cause a larger inductor current ripple, which causes larger negative inductor current in Forced PWM mode at low or no output current. Therefore, they are not recommended at large voltages across the inductor as it is the case for high input voltages and low output voltages. With low output current in Forced PWM mode, this causes a larger negative inductor current peak that can exceed the negative current limit. At low or no output current and small inductor values the output voltage can therefore not be regulated any more. More detailed information on further LC combinations can be found in Optimizing the TPS62130/40/50/60 Output Filter Application Report.
The inductor selection is affected by several effects like the following:
In addition, the inductor selected has to be rated for appropriate saturation current and DC resistance (DCR). Equation 14 calculates the maximum inductor current.
where:
Calculating the maximum inductor current using the actual operating conditions gives the minimum saturation current of the inductor needed. It is recommended to add a margin of about 20%. A larger inductor value is also useful to get lower ripple current, but increases the transient response time and size as well. The following inductors have been used with the TPS629210-Q1 and are recommended for use:
TYPE | INDUCTANCE [µH] | DCR [mΩ] | CURRENT [A]^{(1)} | DIMENSIONS [L×B×H] mm | MANUFACTURER |
---|---|---|---|---|---|
DFE252012PD-2R2M | 2.2 µH, ±20% | 84 | 2.8 | 2.5 × 2.0 × 1.2 | muRata |
XGL3530-222ME | 2.2 μH, ±20% | 20 | 4.0 | 3.5 × 3.2 × 3 | Coilcraft |
XGL4020-222ME | 2.2 µH, ±20% | 19.5 | 6.2 | 4 × 4 × 2.1 | Coilcraft |
XGL4020-472ME | 4.7 µH, ±20% | 43 | 4.1 | 4 × 4 × 2.1 | Coilcraft |
The inductor value also determines the load current at which Power Save mode is entered: