ISL6551EVAL1 Intersil, ISL6551EVAL1 Datasheet - Page 20

• Manufacturer Part Number: ISL6551EVAL1
• Description: EVALUATION BOARD ISL6551
• Manufacturer: Intersil

Specifications of ISL6551EVAL1

• Main Purpose: DC/DC, Step Down
• Outputs And Type: 1, Isolated
• Voltage - Output: 3.3V
• Current - Output: 60A
• Voltage - Input: 36 ~ 75V
• Regulator Topology: Buck
• Frequency - Switching: 470kHz
• Board Type: Fully Populated
• Utilized Ic / Part: ISL6551
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Power - Output: -

Table 3 summarizes a rough full load power losses analysis
for 3.3V output of the reference design.
PARAMETER
TABLE 2. DESIGN PARAMETER REQUIREMENTS (Continued)
Ipriavgres
Isynpeak
Iprirsmtr
Iprirsmtr
Ipripeak
Ipriavgfr
Isynrms
Psynfet
Plowfet
Iprirms
Pupfet
Nmax
Iprms
Isrms
Imag
Ncs
Pdr
Pdr
N
V
Td=40n. The worse case could be at
Vin=75V, Four Siliconix Si4842DYs.
Vin=36V, Vd=0.75V, Vo=3.63V with
GS
Vcc(max)=13.2V, Qg=30nC x 4 at
Recovery Losses are not Included
Vcc(max)=13.2, Qg=50nC x 2 at
Lmag=60uH (Limited by Core),
Vin=75V, Vd=0.78V, Vo=3.63V
Vin=75 due to switching losses
CURRENT TRANSFORMER
=10V, Two Siliconix SUD40N10-
Body Diode Conduction and
Vmisc=0.3V, Dmaxav=0.85
Vin=36V, Vomax=3.63V,
MAIN TRANSFORMER
SYNCHRONOUS FETs
Four Siliconix Si4842DY
PRIMARY SWITCHES
Each Secondary Driver
VIN=75V, Vo=3.63V
Each Primary Driver
Vin=75V, Vo=3.63V
Vin=75V, Vo=3.63V
Vin=36V, Vo=3.63V
Vin=75V, Vo=3.63V
Vin=75V, Vo=3.63V
Vin=36V, Vo=3.63V
Vin=75V, Vo=3.63V
Vin=75V, Vo=3.63V
Vin=75V, Vo=3.63V
Limited by Core
Vo=3.63V, Fsw
CONDITION
V
20
GS
Here
25
=4.5V
Application Note 1002
VALUE UNIT
150:1
0.095
0.92
11.4
33.4
3.77
4.94
2.57
3.71
0.42
0.90
66.4
42.5
1.09
9.9
7:2
3.6
4.1
2.3
W
W
W
W
W
A
A
A
A
A
A
A
A
A
A
A
-
-
-
Secondary Winding Copper
Clamping Losses, and Error
Pinouts of Current Sense
Recovery Losses at Bridge
FETs, Contact Resistance,
Core (20% of Conduction)
Biases other than Drivers
Guess Overall Magnetics
Output Inductors Copper
Conduction and Reverse
Transformer Turns Ratio
MOSFET Rds(on) Value
Primary Winding Copper
Current Sense Rectifiers
Upper FETs Conduction
Lower FETs Conduction
Magnetizing Inductance
Current Sense Resistor
FETs and Synchronous
Current Sense Winding
Miscounted Switching
Losses, Body Diodes
Switching Frequency
Synchronous Drivers
Synchronous FETs
Full Bridge Drivers
Clock Dead Time
TABLE 3. FULL LOAD POWER LOSSES ANALYSIS
Output Inductor
Resonant Time
Transformer
PCB Copper
ELEMENTS
Conduction
TOTAL
R22
Td
CALCULATION CONDITIONS
SECONDARY SIDE
PRIMARY SIDE
OTHERS
2.616W
1.023W
0.110W
1.521W
0.677W
2.290W
1.005W
2.575W
1.805W
0.122W
0.075W
0.656W
1.096W
0.360W
0.942W
3.914W
27.33W
0.819w
36V
POWER DISSIPATION
AT 60A LOAD
at Tj=50
1.8056W
235kHz
3.371W
0.630W
1.087W
0.082W
1.141W
0.677W
2.293W
1.054W
2.642W
0.095W
0.055W
0.697W
1.126W
0.360W
0.973W
3.492W
27.87W
175ns
0.8uH
60uH
50ns
40ns
48V
7:2
0
C
4.179W
0.427W
1.155W
0.053W
0.731W
0.677W
2.296W
1.106W
2.716W
1.805W
0.063W
0.034W
0.741W
1.157W
0.360W
5.625W
31.03W
1.006w
75V