SC4525D View Datasheet(PDF) - Semtech Corporation
Part Name
Description
MFG CO.
'SC4525D' PDF : 21 Pages View PDF
SC4525D
Applications Information (Cont.)
P TOTAL= PC + P S W + PB S T + PQ
(13)
The temPCp=erDat⋅uVrCeErSisAeT⋅oIOf
total power dissipation
the SC4525D PisQth=eVpINro⋅ 2dmucAt of the
(Equation (13)) and qJA (36oC/W),
wfohr itchhePisSSOtWhICe=-t182heE⋅rDtmSPa⋅plVaiImNck⋅pIaOegd⋅eaF.nS Wce from junction to ambient
I1t2i5soCnojPutBnSrcTet=ciooDnm⋅tmVeBmeSnTpd⋅ee4rIOda0tutore.operate the SC4525D above
PCB LaPyDo=ut(1C−onDs)i⋅dVeDra⋅ ItOions
In a step-down switching regulator, the input bypass
capacitPoINrD, t=he(1m.1a~in1.p3o)w⋅ Ie2Or⋅ RswDCitch and the freewheeling
diode carry pulse current (Figure 9). For jitter-free
operation, the size of the loop formed by these components
should be minimized. Since the power switch is already
integrated within the SC4525D, connecting the anode of
the freewheeling diode close to the negative terminal of
the input bypass capacitor minimizes size of the switched
current loop. The input bypass capacitor should be placed
close to the IN pin. Shortening the traces of the SW and
BST nodes reduces the parasitic trace inductance at these
nodes. This not only reduces EMI but also decreases
switching voltage spikes at these nodes.
The exposed pad should be soldered to a large ground
plane as the ground copper acts as a heat sink for the
device. To ensure proper adhesion to the ground plane,
avoid using vias directly under the device.
V IN
VOUT
ZL
Figure 9. Heavy lines indicate the critical pulse
current loop. Thes stray inductance of this
loop should be minimized.
Vin
C
+
+
© 2011 Semtech Corp.
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