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ZHCSB85F November 2011 – October 2021 TPS62140 , TPS62140A , TPS62141 , TPS62142 , TPS62143

PRODUCTION DATA

9.2.2.2 External Component Selection

The external components have to fulfill the needs of the application, but also the stability criteria of the devices control loop. The TPS6214x is optimized to work within a range of external components. The inductance of the LC output filter and capacitance have to be considered in conjunction, creating a double pole, responsible for the corner frequency of the converter (see Section 9.2.2.4). Table 9-2 can be used to simplify the output filter component selection. Checked cells represent combinations that are proven for stability by simulation and lab test. Further combinations should be checked for each individual application. See Optimizing the TPS62130/40/50/60 Output Filter Application Report for details.

Table 9-2 Recommended LC Output Filter Combinations

	10 µF	22 µF	47 µF	100 µF	200 µF
0.47 µH⁽¹⁾
1 µH		√	√	√	√
2.2 µH	√	√⁽²⁾	√	√	√
3.3 µH	√	√	√	√
4.7 µH

(1) The values in the table are nominal values. The effective capacitance was considered to vary by +20% and -50%.

(2) This LC combination is the standard value and recommended for most applications.

The TPS6214x can be run with an inductor as low as 1 µH or 2.2 µH. FSW should be set low in this case. However, for applications running with the low-frequency setting (FSW = high) or with low input voltages, 3.3 µH is recommended.

Note:

DC bias effect: High-capacitance ceramic capacitors have a DC bias effect, which has a strong influence on the final effective capacitance. Therefore, the right capacitor value must be chosen carefully. Package size and voltage rating in combination with dielectric material are responsible for differences between the rated capacitor value and the effective capacitance.