DC1245A Linear Technology, DC1245A Datasheet - Page 13

• Manufacturer Part Number: DC1245A
• Description: BOARD DEMO LTM4616
• Manufacturer: Linear Technology
• Series: µModuler

Specifications of DC1245A

• Design Resources: LTM4616 Spice Model LTM4616 Gerber Files DC1245 Design Files
• Main Purpose: DC/DC, Step Down
• Outputs And Type: 2, Non-Isolated
• Power - Output: -
• Voltage - Output: 1.2V, 1.8V
• Current - Output: 8A, 8A
• Voltage - Input: 2.7 ~ 5.5 V
• Regulator Topology: Buck
• Frequency - Switching: 1.5MHz
• Board Type: Fully Populated
• Utilized Ic / Part: LTM4616
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

applications inForMation
The LTM4616 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. Tie the I
share the current. Current sharing is inherently guaranteed
by the current mode operation of the LTM4616’s DC/DC
regulators. Moreover, the accuracy of current sharing be-
tween the two outputs is approximately ±15%. To reduce
ground potential noise, tie the I
together and then connect to the SGND of the master at
the point it connects to the output capacitor GND. See
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
PHASE 1
PHASE 1
PHASE 4
0
90
CLKOUT
0
CLKOUT
CLKOUT
TH
+120
+120
+120
pins of each LTM4616 together to
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
V
IN
LTC6908-2
PHASE 3
PHASE 5
PHASE 8
120
120
210
CLKOUT
CLKOUT
CLKOUT
THM
OUT1
OUT2
pins of all LTM4616s
+120
+120
+120
S
S
S
VIN
VIN
VIN
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
Figure 3. 12-Phase Operation
Figure 2. 6-Phase Operation
PHASE 5
PHASE 12
PHASE 9
240
240
330
CLKOUT
CLKOUT
CLKOUT
+180
+180
+180
layout guideline in Figure 17. Figure 19 shows a schematic
of the parallel design. The FB pins of the parallel module
are tied together.
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 4 shows this graph.
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
PHASE 2
PHASE 3
PHASE 6
(420)
(420)
(510)
150
60
60
CLKOUT
CLKOUT
CLKOUT
+120
+120
+120
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
PHASE 10
PHASE 4
PHASE 7
180
180
270
CLKOUT
CLKOUT
CLKOUT
+120
+120
+120
LTM4616
CLKIN
PHMODE
CLKIN
PHMODE
CLKIN
PHMODE
PHASE 6
PHASE 11
PHASE 2
(390)
300
300
30
CLKOUT
CLKOUT
CLKOUT
13
4616 F03
4616fc
4616 F02