Inductor trimming

Inductor trimming by ground plane structuring with a laser. 

Here we should actually check the IC datasheet to see the MAX value of the current limit range. For example, for a 5 A switcher the MIN value may be say 6 A (set high enough simply to guarantee full 5 A load capability with the usual 20% inductor design criterion mentioned above), but the MAX value of the current limit may be say 7 A over temperature and process variations, and depending upon how it may have been trimmed in production. 

Printed inductor structures can be adjusted by laser trimming. In general, three methods are possible. They are ... 

Trimming of inductors by increasing the effective current path. 

The first method is based on increasing the effective electrical path by cutting into the conductor. It can be applied on meander and spiral type of inductors (Figure 9.48). The inductor is trimmed toward higher inductances. 

The ZRBC is a standard non-isolated boost converter, with the conventional inductor replaced by a zero-ripple inductor (ZRI). The secondary winding of the ZRI is connected to an external trimming inductor and a filter capacitor as shown in Fig. 24. Unlike the boost converter, the input current in a ZRBC is split between the two windings of the ZRI, as shown in Fig. 25. The primary winding conducts the DC current while the secondary winding conducts the AC current, thereby, making the output current of the fuel cell ripple free. 

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