S

= 71 pF

1

S

= 1.99 nF

=

100 kHz

17.4 kHz

10 k:

0.8 V

5.0 V

= 9.2 k:

2

2

1

=

1

1

=

LM21215A

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SNOSB87B – MARCH 2011 – REVISED MARCH 2013

The dependancy of the pole and zero locations on the compensation components is described below.

An example of the step-by-step procedure to generate compensation component values using the typical

application setup (see Figure 40) is given. The parameters needed for the compensation values are given in the

table below.

Parameter

Value

5.0V

1.2V

15A

100 kHz

L

0.56 µH

1.8 m

Ω

150 µF

1.0 m

Ω

0.8V

500 kHz

where

Layer Ceramic Capacitors (MLCC), the total capacitance will degrade as the DC bias voltage is increased.

Measuring the actual capacitance value for the output capacitors at the output voltage is recommended to

accurately calculate the compensation network. The example given here is the total output capacitance using the

three MLCC output capacitors biased at 1.2V, as seen in the typical application schematic, Figure 40. Note that it

is more conservative, from a stability standpoint, to err on the side of a smaller output capacitance value in the

compensation calculations rather than a larger, as this will result in a lower bandwidth but increased phase

margin.

calculated to set the mid-band gain so that the desired crossover frequency is achieved:

(13)

(14)

(15)

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