isl6312a Intersil Corporation, isl6312a Datasheet - Page 13

• Manufacturer Part Number: isl6312a
• Description: Four-phase Buck Pwm Controller With Integrated Mosfet Drivers For Intel Vr10, Vr11, And Amd Applications
• Manufacturer: Intersil Corporation

If the R-C network components are selected such that the
RC time constant matches the inductor L/DCR time
constant, then V
DCR multiplied by the ratio of the resistor divider, K. If a
resistor divider is not being used, the value for K is 1.
The capacitor voltage V
sense resistor R
proportional to the inductor current. Equation 7 shows that
the proportion between the channel current and the sensed
current (I
the resistor divider ratio, and the DCR of the inductor.
Output Voltage Setting
The ISL6312A 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 logic signals into one of
the discrete voltages shown in Tables 2, 3, 4 and 5. In Intel
modes of operation, each VID pin is pulled up to an internal
1.2V voltage by a weak current source (40μA), which
decreases to 0A as the voltage at the VID pin varies from 0
to the internal 1.2V pull-up voltage. In AMD modes of
operation the VID pins are pulled low by a weak 20μA
current source. External pull-up resistors or active-high
output stages can augment the pull-up current sources, up to
a voltage of 5V.
The ISL6312A accommodates four different DAC ranges:
Intel VR10 (Extended), Intel VR11, AMD K8/K9 5-bit, and
AMD 6-bit. The state of the VRSEL and VID7 pins decide
which DAC version is active. Refer to Table 1 for a
description of how to select the desired DAC version.
K
I
V
SEN
C
VR10(Extended)
=
DAC VERSION
s ( )
-------------------- -
R
AMD 5-Bit
AMD 6-Bit
=
2
=
R
VR11
+
K I
2
SEN
------------------------------------------------------- - K DCR I
⎛
⎜
⎝
R
⋅
s
TABLE 1. ISL6312A DAC SELECT TABLE
1
L
⋅
(
----------------------- - C
) is driven by the value of the sense resistor,
⋅
R
R
⎛
⎝
----------------- -
R
-------------
DCR
1
DCR
1
s L
ISEN
C
ISEN
+
⋅
⋅
R
R
is equal to the voltage drop across the
2
2
+
)
0.8V < VRSEL < 3.0V
3.0V < VRSEL < VCC
3.0V < VRSEL < VCC
. The current through R
⋅
1
⎞
⎠
C
VRSEL < 0.6V
+
VRSEL PIN
, is then replicated across the
1
⎞
⎟
⎠
13
⋅
⋅
⋅
L
ISEN
VID7 PIN
high
low
is
-
-
(EQ. 7)
(EQ. 5)
(EQ. 6)
ISL6312A
VID4
TABLE 2. VR10 (EXTENDED) VOLTAGE IDENTIFICATION
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
VID3
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
0
0
0
0
0
0
0
0
0
0
0
0
CODES
VID2
0
0
0
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
VID1
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
1
1
1
0
VID0
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
VID5
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
1
0
VID6
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
August 1, 2007
1.60000
1.59375
1.58750
1.58125
1.57500
1.56875
1.56250
1.55625
1.55000
1.54375
1.53750
1.53125
1.52500
1.51875
1.51250
1.50625
1.50000
1.49375
1.48750
1.48125
1.47500
1.46875
1.46250
1.45625
1.45000
1.44375
1.43750
1.43125
1.42500
1.41875
1.41250
1.40625
1.40000
1.39375
1.38750
1.38125
1.37500
1.36875
1.36250
VDAC
FN9290.3