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SC2440

POWER MANAGEMENT

Applications Information

Board Layout Considerations

In a step-down switching regulator, the input bypass

capacitor, the main power switch and the freewheeling

diode carry switched currents with high

dt

di

(Figure 15).

For jitter-free operation, the size of the loop formed by

these components should be minimized. Since the power

switches are already integrated within the SC2440,

connecting the anodes of both freewheeling diodes close

to the negative terminal of the input bypass capacitor

minimizes size of the switched current loop. The input

bypass capacitors should also be placed close to the

Figure 14. Overall Loop Gain and Phase versus Frequency for (a) Channel 1 and (b) Channel 2 of the Dual

DC-DC Converter in Figure 1. (c) Channel 1 Load Transient Response, I

0.3A and 1.7A. (d) Channel 2 Load Transient Response, I

1.7A.

Upper Trace : OUT1 Voltage, AC Coupled, 0.5V/div

Lower Trace : L

Upper Trace : OUT2 Voltage, AC Coupled, 0.5V/div

Lower Trace : L

(d)

(c)

40µs/div

V

40µs/div

V

(a)

V

C

(b)

V

C