ISL6334 Datasheet, PDF(18/30 Page) Intersil Corporation – VR11.1, 4-Phase PWM Controller with Light Load Efficiency Enhancement and Load Current Monitoring

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ISL6334 Datasheet, PDF (18/30 Pages) Intersil Corporation – VR11.1, 4-Phase PWM Controller with Light Load Efficiency Enhancement and Load Current Monitoring

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ISL6334, ISL6334A

TABLE 2. VR11 VID 8 BIT (Continued)

VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 VOLTAGE

0 1 1 1 1 1 1 0 0.82500

0 1 1 1 1 1 1 1 0.81875

1 0 0 0 0 0 0 0 0.81250

1 0 0 0 0 0 0 1 0.80625

1 0 0 0 0 0 1 0 0.80000

1 0 0 0 0 0 1 1 0.79375

1 0 0 0 0 1 0 0 0.78750

1 0 0 0 0 1 0 1 0.78125

1 0 0 0 0 1 1 0 0.77500

1 0 0 0 0 1 1 1 0.76875

1 0 0 0 1 0 0 0 0.76250

1 0 0 0 1 0 0 1 0.75625

1 0 0 0 1 0 1 0 0.75000

1 0 0 0 1 0 1 1 0.74375

1 0 0 0 1 1 0 0 0.73750

1 0 0 0 1 1 0 1 0.73125

1 0 0 0 1 1 1 0 0.72500

1 0 0 0 1 1 1 1 0.71875

1 0 0 1 0 0 0 0 0.71250

1 0 0 1 0 0 0 1 0.70625

1 0 0 1 0 0 1 0 0.70000

1 0 0 1 0 0 1 1 0.69375

1 0 0 1 0 1 0 0 0.68750

1 0 0 1 0 1 0 1 0.68125

1 0 0 1 0 1 1 0 0.67500

1 0 0 1 0 1 1 1 0.66875

1 0 0 1 1 0 0 0 0.66250

1 0 0 1 1 0 0 1 0.65625

1 0 0 1 1 0 1 0 0.65000

1 0 0 1 1 0 1 1 0.64375

1 0 0 1 1 1 0 0 0.63750

1 0 0 1 1 1 0 1 0.63125

1 0 0 1 1 1 1 0 0.62500

1 0 0 1 1 1 1 1 0.61875

1 0 1 0 0 0 0 0 0.61250

1 0 1 0 0 0 0 1 0.60625

1 0 1 0 0 0 1 0 0.60000

1 0 1 0 0 0 1 1 0.59375

1 0 1 0 0 1 0 0 0.58750

1 0 1 0 0 1 0 1 0.58125

TABLE 2. VR11 VID 8 BIT (Continued)

VID7 VID6 VID5 VID4 VID3 VID2 VID1 VID0 VOLTAGE

1 0 1 0 0 1 1 0 0.57500

1 0 1 0 0 1 1 1 0.56875

1 0 1 0 1 0 0 0 0.56250

1 0 1 0 1 0 0 1 0.55625

1 0 1 0 1 0 1 0 0.55000

1 0 1 0 1 0 1 1 0.54375

1 0 1 0 1 1 0 0 0.53750

1 0 1 0 1 1 0 1 0.53125

1 0 1 0 1 1 1 0 0.52500

1 0 1 0 1 1 1 1 0.51875

1 0 1 1 0 0 0 0 0.51250

1 0 1 1 0 0 0 1 0.50625

1 0 1 1 0 0 1 0 0.50000

1 1 1 1 1 1 1 0 OFF

1 1 1 1 1 1 1 1 OFF

Load-Line Regulation

Some microprocessor manufacturers require a precisely

controlled output resistance. This dependence of output

voltage on load current is often termed âdroopâ or âload lineâ

regulation. By adding a well controlled output impedance,

the output voltage can effectively be level shifted in a

direction, which works to achieve the load-line regulation

required by these manufacturers.

In other cases, the designer may determine that a more

cost-effective solution can be achieved by adding droop.

Droop can help to reduce the output-voltage spike that

results from fast load-current demand changes.

The magnitude of the spike is dictated by the ESR and ESL

of the output capacitors selected. By positioning the no-load

voltage level near the upper specification limit, a larger

negative spike can be sustained without crossing the lower

limit. By adding a well controlled output impedance, the

output voltage under load can effectively be level shifted

down so that a larger positive spike can be sustained without

crossing the upper specification limit.

As shown in Figure 6, a current proportional to the average

current of all active channels, IAVG, flows from FB through a

load-line regulation resistor RFB. The resulting voltage drop

across RFB is proportional to the output current, effectively

creating an output voltage droop with a steady-state value

defined as shown in Equation 8:

VDROOP = IAVG RFB

(EQ. 8)

FN6482.0

February 26, 2008

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