SC2440 SEMTECH [Semtech Corporation], SC2440 Datasheet - Page 21

• Manufacturer Part Number: SC2440
• Description: 2.5 MHz Dual Switching Regulator with Integrated 2A Switches
• Manufacturer: SEMTECH [Semtech Corporation]

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
POWER MANAGEMENT
Applications Information
2005 Semtech Corp.
Upper Trace : OUT1 Voltage, AC Coupled, 0.5V/div
Lower Trace : L
Figure 14. Overall Loop Gain and Phase versus Frequency for (a) Channel 1 and (b) Channel 2 of the Dual
V
C
IN
5
=470pF, R
=12V, V
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.
OUT
1
=3.3V at 1.7A,
5
=15.4K
Inductor Current, 0.5A/div
40 s/div
(a)
(c)
and C
V
6
OUT
=10pF
=3.3V
dt
di
(Figure 15).
21
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
Upper Trace : OUT2 Voltage, AC Coupled, 0.5V/div
Lower Trace : L
V
C
IN
7
=220pF, R
=12V, V
OUT2
OUT
2
=5V at 1.7A,
8
is switched between 0.45A and
=24.3K
Inductor Current, 0.5A/div
40 s/div
(b)
(d)
OUT1
and C
is switched between
9
V
=10pF
OUT
=5V
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SC2440