Modifications
1-5
Introduction
Figure 1−1. Frequency Trimming Resistor Selection Graph
250
300
350
400
450
500
550
600
650
700
750
60
80
100
120
140
160
180
Switching Frequency − kHz
R − Resistance − k
Ω
An onboard electrolytic input capacitor may be added at C1.
1.3.3
Power Sequencing
By selecting different R6−R7 resistor divider ratios, different power
sequencing scenarios can be set. The Equations 1−3, 1−4, and 1−5 show how
to select the different ways of power sequencing.
Equation 1−3.
R6
R7
+
R1
R2
*
Core voltage tracks I
ń
O voltage
Equation 1−4.
R6
R7
+
ǒ
V
I
ń
O
*
0.891
Ǔ
0.891
− Ratiometric relation between core and I/O
voltage
Equation 1−5.
R6
R7
t
R1
R2 − Core voltage rises first at power up and falls second
at power down
Summary of Contents for TPS54980EVM-022
Page 1: ...E September 2003 PMP Systems Power User s Guide SLVU090...
Page 8: ...4...
Page 14: ...1 6...
Page 29: ...Layout 3 3 Board Layout Figure 3 2 Internal Layer 2 Figure 3 3 Internal Layer 3...
Page 30: ...Layout 3 4 Figure 3 4 Bottom Side Layout looking from top side Figure 3 5 Top Side Assembly...
