isl6566a Intersil Corporation, isl6566a Datasheet - Page 11

• Manufacturer Part Number: isl6566a
• Description: Three-phase Buck Pwm Controller With Two Integrated Mosfet Drivers And One External Driver Signal
• Manufacturer: Intersil Corporation

The ISL6566A senses the channel load current by sampling
the voltage across the lower MOSFET r
Figure 5. A ground-referenced operational amplifier, internal
to the ISL6566A, is connected to the PHASE node through a
resistor, R
the voltage drop across the r
while it is conducting. The resulting current into the ISEN pin
is proportional to the channel current, I
sampled and held as described in the Current Sampling
section. From Figure 5, the following equation for I
derived where I
Output Voltage Setting
The ISL6566A uses a digital to analog converter (DAC) to
generate a reference voltage based on the logic signals at the
VID pins. The DAC decodes the 5 or 6-bit logic signals into
one of the discrete voltages shown in Tables 2, 3, and 4.
Each VID pin is pulled up to an internal 1.2V voltage by a
weak current source (40µA current), which decreases to 0 as
the voltage at the VID pin varies from 0 to the internal 1.2V
pull-up voltage. External pull-up resistors or active-high
output stages can augment the pull-up current sources, up to
a voltage of 5V.
.
The ISL6566A accommodates three different DAC ranges:
Intel VRM9.0, AMD Hammer, or Intel VRM10.0. The state of
the VRM10 and VID12.5 pins decide which DAC version is
active. Refer to Table 1 for a description of how to select the
desired DAC version.
I
n
SAMPLE
ISL6565A INTERNAL CIRCUIT
HOLD
FIGURE 5. ISL6566A INTERNAL AND EXTERNAL CURRENT-
=
DAC VERSION
AMD HAMMER
I
&
I
n
L
VRM10.0
VRM9.0
r
----------------------
DS ON
R
I
SEN
ISEN
ISEN
TABLE 1. ISL6566A DAC SELECT TABLE
(
SENSING CIRCUITRY FOR CURRENT BALANCE
=
)
. The voltage across R
L
I
L
is the channel current.
r
------------------------- -
+
DS ON
R
-
ISEN
(
VRM10 PIN
)
High
Low
Low
DS(ON)
11
ISEN(n)
EXTERNAL CIRCUIT
CHANNEL N
LOWER MOSFET
R
of the lower MOSFET
ISEN
ISEN
L
. The ISEN current is
DS(ON)
V
is equivalent to
IN
VID12.5 PIN
+
CHANNEL N
UPPER MOSFET
-
I L r DS ON
, as shown in
High
Low
-
n
I
L
is
(
(EQ. 3)
)
ISL6566A
ISL6566A
TABLE 2. AMD HAMMER VOLTAGE IDENTIFICATION CODES
VID4
VID4
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
TABLE 3. VRM9 VOLTAGE IDENTIFICATION CODES
VID3
VID3
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
VID2
VID2
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
VID1
VID1
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
VID0
VID0
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
July 27, 2005
VDAC
VDAC
0.800
0.825
0.850
0.875
0.900
0.925
0.950
0.975
1.000
1.025
1.050
1.075
1.100
1.125
1.150
1.175
1.200
1.225
1.250
1.275
1.300
1.325
1.350
1.375
1.400
1.425
1.450
1.475
1.500
1.525
1.550
1.100
1.125
1.150
1.175
FN9200.2
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