ISL6561 Intersil Corporation, ISL6561 Datasheet - Page 14

• Manufacturer Part Number: ISL6561
• Description: Multi-Phase PWM Controller with Precision Rds(on) or DCR Differential Current Sensing for VR10.X Application
• Manufacturer: Intersil Corporation

TABLE 1. VOLTAGE IDENTIFICATION (VID) CODES (Continued)
VID4
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
VID3
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
VID2
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
VID1
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
0
14
VID0
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
VID12.5
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
1.0625V
1.0750V
1.0875V
1.1000V
1.1125V
1.1250V
1.1375V
1.1500V
1.1625V
1.1750V
1.1875V
1.2000V
1.2125V
1.2250V
1.2475V
1.2500V
1.2625V
1.2750V
1.2875V
1.3000V
1.3125V
1.3250V
1.3375V
1.3500V
1.3625V
1.3750V
1.3875V
1.4000V
1.4125V
1.4250V
1.4375V
1.4500V
1.4625V
1.4750V
1.4875V
1.5000V
1.5125V
1.5250V
VDAC
OFF
OFF
ISL6561
In other cases, the designer may determine that a more
cost-effective solution can be achieved by adding droop.
Droop can help to control 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 8, a current proportional to the average
current in all active channels, I
load-line regulation resistor, R
across R
creating an output voltage droop with a steady-state value
defined as
The regulated output voltage is reduced by the droop
voltage V
current is derived by combining Equations 8 with the
appropriate sample current expression defined by the
current sense method employed.
Where V
programmed offset voltage, I
of the converter, R
and R
r
Output-Voltage Offset Programming
The ISL6561 allows the designer to accurately adjust the
offset voltage. When a resistor, R
OFS and VCC, the voltage across it is regulated to 2.0V.
This causes a proportional current (I
R
regulated to 0.5V, and I
V
V
TABLE 1. VOLTAGE IDENTIFICATION (VID) CODES (Continued)
DS(ON)
OUT
OFS
DROOP
VID4
0
0
0
0
0
0
FB
is connected to ground, the voltage across it is
=
, or R
V
REF
FB
is the feedback resistor. R
DROOP
VID3
=
REF
1
1
1
1
1
1
I
is proportional to the output current, effectively
AVG
is the reference voltage, V
SENSE
–
V
VID2
. The output voltage as a function of load
R
OFFSET
ISEN
1
1
1
0
0
0
FB
depending on the sensing method.
is the sense resistor in the ISEN line,
OFS
VID1
–
0
0
0
1
1
1
I
-------------
flows out of OFS. A resistor
OUT
OUT
4
FB
AVG
VID0
. The resulting voltage drop
OFS
----------------- - R
R
is the total output current
1
0
0
1
1
0
, flows from FB through a
ISEN
R
X
OFS
X
, is connected between
has a value of DCR,
OFS
VID12.5
) to flow into OFS. If
FB
0
1
0
1
0
1
is the
1.5375V
1.5500V
1.5625V
1.5750V
1.5875V
1.600V
VDAC
(EQ. 8)
(EQ. 9)