SC2620 Semtech Corporation, SC2620 Datasheet - Page 21

• Manufacturer Part Number: SC2620
• Description: 30V Step-down Regulator
• Manufacturer: Semtech Corporation

For the 1.2V channel:
Bench measurement shows that compensation
components computed from our simplified linear model
give very good load transient response for Channel 1 (Figure
13(a)). However, optimizing load transient for Channel 2
will require a set of compensation component values
different from those calculated above. Loop compensation
networks shown in Figure 1(a) are empirically optimized
for load transients. Figures 13(a) and 13(b) show the
corresponding load transient responses.
POWER MANAGEMENT
Applications Information
2008 Semtech Corp.
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Fast Switching Current Paths in a Buck
Regulator. Minimize the size of this loop
to reduce parasitic trace inductance.
)
21
Board Layout Considerations
In a step-down switching regulator, the input bypass
capacitor, the main power switch and the freewheeling
diode carry discontinuous currents with high
14). 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 SC2620,
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 be placed close to the PVIN pins.
Shortening the traces of the SW and BOOST nodes reduces
the parasitic trace inductance at these nodes. This not
only reduces EMI but also decreases switching voltage
spikes at these nodes.
The PVIN bypass capacitor C
capacitors and the freewheeling diodes are to be grounded
on the power ground plane (Figure 15). The feedback
resistive dividers, the compensation networks, the soft-
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L
V
OUT
15
, the output filtering
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SC2620
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di
(Figure