TPS61010, TPS61011
TPS61012, TPS61013
TPS61014, TPS61015, TPS61016
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SLVS314C–SEPTEMBER 2000–REVISED OCTOBER 2003
DESIGN PROCEDURE (continued)
Capacitor CC1 depends on the ESR and capacitance value of the output capacitor, and on the value chosen for
RC. Its value is calculated using Equation 7.
C
ESR
OUT
COUT
C
+
C1
R
C
(7)
For a selected output capacitor of 22 µF with an ESR of 0.2Ω , an RC of 33 kΩ, the value of CC1 is in the range
of 100 pF.
Table 2. Recommended Compensation Components
OUTPUT CAPACITOR
INDUCTOR[µH]
RC[kΩ]
CC1[pF]
CC2[nF]
CAPACITANCE[µF]
ESR[Ω]
0.2
33
22
10
10
22
22
22
10
33
120
150
100
10
33
22
10
10
0.3
47
0.4
100
100
0.1
LAYOUT CONSIDERATIONS
As for all switching power supplies, the layout is an important step in the design, especially at high peak currents
and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as
well as EMI problems.
Therefore, use wide and short traces for the main current path as indicated in bold in Figure 25. The input
capacitor, output capacitor, and the inductor should be placed as close as possible to the IC. Use a common
ground node as shown in Figure 25 to minimize the effects of ground noise. The compensation circuit and the
feedback divider should be placed as close as possible to the IC. To layout the control ground, it is
recommended to use short traces as well, separated from the power ground traces. Connect both grounds close
to the ground pin of the IC as indicated in the layout diagram in Figure 25. This avoids ground shift problems,
which can occur due to superimposition of power ground current and control ground current.
U1
L1
SW
VOUT
LBO
R4
LBO
Battery
C4
C1
OUTPUT
VBAT
R2
R3
R5
R6
LBI
FB
R1
C2
ADEN
COMP
C3
EN
GND
Figure 25. Layout Diagram
18
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