SC411 Semtech Corporation, SC411 Datasheet - Page 16

• Manufacturer Part Number: SC411
• Description: Synchronous Buck Pseudo-Fixed Frequency Power Supply Controller
• Manufacturer: Semtech Corporation

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I
V
Q
f
VBST
D
Inserting the following values for VBAT
this is the worst case condition for power dissipation in
the controller) as an example (VOUT = 1.2V),
T
θ
VCCA
I
I
V
Q
f
VBAT
VBST
D
gives us,
and,
As can be seen, the heating effects due to internal power
dissipation are practically negligible, thus requiring no
special thermal consideration during layout.
The Reference Design is shown in Figure on Page 17.
An additional design optimized for effi ciency and capable
of a higher load current of 10A is shown in Figure 11 on
Page 21.
© 2007 Semtech Corp.
P
+
=
T
VDDP
VCCA
VDDP
POWER MANAGEMENT
A
Application Information (Cont.)
g
g
JA
D
g
g
(MIN)
J
5
. 0
=
=
•
088
85
5
60
(MIN)
(MIN)
•
+
1100
•
= gate drive operating current (A)
= gate drive voltage, typically 5V (V)
= FET gate charge, from the FET datasheet (C)
= switching frequency (kHz)
= boost pin voltage during t
= duty cycle
= 1.2/8 = 0.15
= 85°C
= 100°C/W
= VDDP = 5V
= 1100μA (data sheet maximum)
= 150μA (data sheet maximum)
= 5V
= 60nC
= 266kHz
10
. 0
= 8V
= VBAT
W
088
−
9
•
•
10
•
266
100
−
(MIN)
6
+
•
5
10
=
+VDDP = 13V
•
93
3
150
+
8 .
13
•
10
•
°
C
1
−
•
6
10
−
3
•
ON
. 0
15
(V)
(MIN)
condition (since
16
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SC411