TPS54383, TPS54386
www.ti.com
SLUS774B–AUGUST 2007–REVISED OCTOBER 2007
GAIN AND PHASE
vs
FREQUENCY
GAIN AND PHASE
vs
FREQUENCY
100
85
270
225
180
135
90
100
270
225
180
135
90
Duty Cycle %
Gain Phase
10
30
50
70
90
80
70
60
40
55
40
45
25
45
20
0
Duty Cycle %
Gain Phase
0
10
0
10
30
50
70
90
-45
-5
-45
-90
-20
-90
-20
100
1 k
10 k
f - Frequency -Hz
100 k
1 M
100
1 k
10 k
f - Frequency - Hz
100 k
1 M
Figure 26. TPS54383 at 600-mApp Ripple Current
Figure 27. TPS54386 at 200-mApp Ripple Current
GAIN AND PHASE
vs
FREQUENCY
GAIN AND PHASE
vs
FREQUENCY
100
85
270
100
80
270
225
180
135
90
225
180
135
90
70
60
40
55
40
45
25
45
20
0
Duty Cycle %
Gain Phase
Duty Cycle %
Gain Phase
0
10
10
0
10
30
50
70
90
30
50
-45
-5
-45
70
90
-90
-20
-20
-90
100
1 k
10 k
f - Frequency -Hz
100 k
1 M
100
1 k
10 k
f - Frequency - Hz
100 k
1 M
Figure 28. TPS54386 at 400-mApp Ripple Current
Figure 29. TPS54386 at 600-mApp Ripple Current
Maximum Output Capacitance
With internal pulse-by-pulse current limiting and a fixed soft start time, there is a maximum output capacitance
which may be used before startup problems begin to occur. If the output capacitance is large enough so that the
device enters a current limit protection mode during startup, then there is a possibility that the output will never
reach regulation. Instead, the TPS5438x simply shuts down and attempts a restart as if the output were
short-circuited to ground. The maximum output capacitance (including bypass capacitance distributed at the
load) is given by Equation 3:
Copyright © 2007, Texas Instruments Incorporated
Submit Documentation Feedback
19
Product Folder Link(s): TPS54383 TPS54386
TI [ TEXAS INSTRUMENTS ]
