SI9140 Datasheet, PDF (14/15 Pages) Vishay Siliconix – SMP Controller For High Performance Process Power Supplies

Si9140
Vishay Siliconix
Worst case current of 10 A can be handled with two paralleled
Si4435DY and two paralleled Si4410DY MOSFETs, which
results in the efficiency levels shown in Figure 9.
Good electrical designs must provide an adequate margin for
the specification, but they should not be grossly overdesigned
to lower costs. LITTLE FOOT power MOSFETs allow
designers to balance cost and performance considerations
without sacrificing either. If the design requires only an 8.5-A
continuous current, for example, one Si4410DY can be
eliminated. Table 2 shows the number of MOSFETs required
to handle the various output current levels of today’s high-
performance microprocessors. For other output power levels,
the equations below should be used to calculate the power
handling capability of the MOSFET.
FIGURE 9. Efficiency
TABLE 2. Converter Requirements Figure 1, 2, and 3)
I_O (A)
Maximum
Quantity High-side
P-Channel SI4435DY
5A
1
8.5 A
2
10 A
2
14.5 A
3
Quantity Low-side
N-Channel SI4410DY
1
1
2
2
Quantity Input (C1-C3)
Capacitor OS-CON 220 µF
1
2
2
3
S-58034—Rev. G, 15-Mar-99
14
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