RC5050
PRODUCT SPECIFICATION
8
Table 3. RC5050 Application Bill of Materials for Intel Pentium II Processors
Notes:
1. In order to meet the voltage transient requirements for the Intel Pentium II Motherboard application, the equivalent ESR of the
output capacitors must not exceed 7.5m
Ω. In order to satisfy the specified Output Voltage Regulation requirements for
VOUT = 1.8V at 15A for next generation processors, the output capacitors must exhibit no more than 6.0m
Ω equivalent ESR
for a motherboard application. The use of the capacitors recommended in Table 1 will address this and other voltage
specifications without significant added cost, although it is left up to the user to specify the components used. Please refer to
Application Bulletin 5 for additional considerations required to meet the Intel Pentium II voltage transient specifications.
2. To optimize a converter for 15A at 1.8V output, fSW = 300 kHz, change the value of L1 to 1.24
µH.
3. Inductor L2 is recommended to isolate the 5V input supply from current surges caused by MOSFET switching. L2 is not
required for normal operation and may be omitted if desired.
4. For 15A designs using IR3103 MOSFETs, heat sinks with thermal resistance
ΘSA < 50°C/W should be used.
Reference
Manufacturer Part #
Description
Requirements/Comments
C4, C5, C7–C11
Panasonic
ECU-V1H104ZFX
0.1
µF 50V capacitor
Cext
Panasonic
ECU-V1H121JCG
100pF capacitor
C12, C6
Panasonic
ECSH1CY105R
1
µF 16V capacitor
CIN
Sanyo
10MV1200EG
1200
µF 10V electrolytic
capacitor 10mm x 20mm
ESR < 62m
Ω
See Table 2
COUT
Sanyo
6MV1500GX
1500
µF 6.3V electrolytic
capacitor 10mm x 20mm
ESR < 44m
Ω
See Note 1 and Table 2
DS1
Motorola MBR2015CT
Schottky Diode
Vf < 0.52 at If = 10A
D1
1N4735A
6.2V Zener Diode,
Motorola
L1
Skynet
320-8107
1.3
µH, 14A inductor
DCR ~ 2.5m
Ω
See Note 2
L2
Skynet
320-6110
2.5
µH, 11A inductor
DCR ~ 6m
Ω
See Note 3
M1, M2
International Rectifier
IRL3103
N-Channel Logic Level
Enhancement Mode MOSFET
RDS(ON) < 19m
Ω
VGS < 4.5V, ID = 15A
See Note 4
RSENSE
Copel
AWG#18
5.5m
Ω CuNi Alloy Wire Resistor
R5
Panasonic
ERJ-6GEY050Y
47
Ω 5% resistor
R6
Panasonic
ERJ-6ENF10.0KV
10K
Ω 5% resistor
Application Information
Simple Step-Down Converter
Figure 3. Simple Buck DC-DC Converter
Figure 3 illustrates a step-down DC-DC converter with no
feedback control. The derivation of the basic step-down
converter will serve as a basis for the design equations for
the RC5050. Referring to Figure 3, the basic operation
begins by closing the switch S1. When S1 is closed, the input
voltage VIN is impressed across inductor L1. The current
flowing in this inductor is given by the following equation:
where TON is the duty cycle (the time when S1 is closed).
C1
RL Vout
+
–
D1
VIN
65-5050-06
L1
S1
I
L
V
IN
V
OUT
–
(
)T
ON
L1
-----------------------------------------------
=
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