LTM4625(RevC) Ver la hoja de datos (PDF) - Analog Devices
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LTM4625 Datasheet PDF : 26 Pages
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LTM4625
APPLICATIONS INFORMATION
0
90
180
270
+90
+90
+90
CLKIN CLKOUT
CLKIN CLKOUT
CLKIN CLKOUT
CLKIN CLKOUT
PHMODE
PHASE 1
PHMODE
PHASE 2
PHMODE
PHASE 3
PHMODE
PHASE 4
0
CLKIN CLKOUT
+120
120
CLKIN CLKOUT
+120
240
CLKIN CLKOUT
+180
(420)
60
CLKIN CLKOUT
+120
180
CLKIN CLKOUT
+120
PHMODE
PHASE 1
PHMODE
PHASE 3
INTVCC
PHMODE
PHASE 5
PHMODE
PHASE 2
PHMODE
PHASE 4
INTVCC
300
CLKIN CLKOUT
PHMODE
PHASE 6
4625 F02
Figure 2. 4-Phase, 6-Phase Operation
0.60
1 PHASE
0.55
2 PHASE
3 PHASE
4 PHASE
0.50
6 PHASE
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0
0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9
DUTY CYCLE (VOUT/VIN)
4625 F03
Figure 3. RMS Input Ripple Current to DC Load Current Ratio as a Function of Duty Cycle
of phases used (assuming that the input voltage is greater
than the number of phases used times the output voltage).
The output ripple amplitude is also reduced by the number
of phases used when all of the outputs are tied together
to achieve a single high output current design.
The LTM4625 device is an inherently current mode con-
trolled device, so parallel modules will have very good
current sharing. This will balance the thermals on the
design. Please tie the RUN, TRACK/SS, FB and COMP pins
of each paralleling channel together. Figure 23 shows an
example of parallel operation and pin connection.
Input RMS Ripple Current Cancellation
Application Note 77 provides a detailed explanation of
multiphase operation. The input RMS ripple current can-
cellation mathematical derivations are presented, and a
graph is displayed representing the RMS ripple current
reduction as a function of the number of interleaved
phases. Figure 3 shows this graph.
Rev C
For more information www.analog.com
11
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