CS5211

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12

Boost Component Selection for Upper FET Gate Drive

The boost (BST) pin provides for application of a higher

voltage to drive the upper FET. This voltage may be

provided by a fixed higher voltage or it may be generated

with a boost capacitor and charging diode, as shown in

Figure 10. The voltage in the boost configuration would be

the summation of the voltage from the charging diode and

the output voltage swing. Care must be taken to keep the

peak voltage with respect to ground less than 20 V peak. The

capacitor should be large enough to drive the capacitance of

the top FET.

+

+

COMP

GATE(H)

GATE(L)

PGND

IS–

CS5211

5.0 V/8.0 A

51 k

0.1

µF

LGND

33

µF/25 V × 3

0.1

µF

SENSE+

4.7 k

1.0 k 1.0%

2.9

µH

12 V

IS+

SENSE–

100

µF/10 V × 2

SGND

4.02 k 1.0%

0.1

µF

0.1

µF

10

BST

12 V

18 V

0.1

µF

33

10

4.7 k

Figure 9. Additional Application Diagram, 12 V to 5.0 V/8.0 A Converter with Differential Remote Sense