isl6263c Intersil Corporation, isl6263c Datasheet - Page 15

• Manufacturer Part Number: isl6263c
• Description: 5-bit Vid Single-phase Voltage Regulator With Current Monitor For Gpu Core Power
• Manufacturer: Intersil Corporation

0.00393 is the temperature coefficient of the copper. To
make V
NTC characteristic is desired to satisfy:
where G
the temperature characteristics G
parameters selection, is described by Equation 17:
It is recommended to begin the DCR current sense design
using the R
evaluation board available from Intersil.
Given the inductor DCR and the overcurrent set point I
maximum voltage of ICOMP pin is determined by
Equation 18:
R
requirement (V
constant matching according to Equation 10.
The effectiveness of the R
coupling coefficient between the NTC thermistor and the
inductor. The NTC thermistor should be placed in the closet
proximity of the inductor.
Resistor Current Sense
Figure 3 shows a detailed schematic using discrete resistor
sense of the inductor current. Figure 9 shows the equivalent
circuit. Since the current sense resistor voltage represents
the actual inductor current information, R
provide noise filtering. A low ESL sense resistor is strongly
recommended for R
G
G
V
N
1
1
ICOMP max
T ( )
T ( )
, R
S
⋅
=
(
, R
ICOMP
1
(
1target
------------------------------------------------------------------------ -
1
+
IS1
+
0.00393 T
NTC
0.00393
)
, R
–
independent of the inductor temperature, the
ICOMP(max)
V
FIGURE 9. EQUIVALENT MODEL OF CURRENT SENSE USING DISCRETE RESISTOR CURRENT SENSE
is the desired ratio of V
, R
IS2
O
G
NTCS
=
⋅
1t
should be adjusted to meet the
SNS
⋅
arg
(
I
T
OC
–
(
–
et
, and R
+25°C
because this parameter is the most
(
⋅
+25°C
DCR 25°C
N
- V
network is sensitive to the
15
O
)
(
)
P
)
) > 25mV and the time
≅
)
OCP
component values of the
1
G
, which determines
1t
)
−
+
+
−
arg
⋅
N
--------------------------------------------- -
R
et
/ V
10µA
N
S
R
(
+25°C
DCR
N
and C
(
+25°C
I
SENSE
↓
. Therefore,
N
)
+
+
−
simply
)
R
(EQ. 16)
(EQ. 17)
OC
OCSET
S
ICOMP
⋅
VDD
, the
⎛
⎜
⎝
ISP
ISN
VO
1
(EQ. 18)
ISL6263C
+
R
------------ -
R
IS2
IS1
R
⎞
⎟
⎠
OCSET
significant source of noise that affects discrete resistor
sense. It is recommended to start out using 100Ω for R
47pF for C
very little with temperature, the NTC network is not needed
for thermal compensation. Discrete resistor sense design
follows the same approach as DCR sense. The voltage on
the current sense resistor is given by Equation 19:
It is optional to parallel a resistor R
with R
R
The current sense amplifier output voltage V
by Equation 21:
Given an current sense resistor R
point I
by Equation 22:
If R
determined by Equation 23:
R
requirement (V
The current sense traces should be routed directly to the
current sense resistor pads for accurate measurement.
However, due to layout imperfection, the calculated R
V
V
V
V
V
RSNS
P
N
ICOMP
ICOMP max
S
ICOMP max
, R
is V
P
=
is not used, the maximum voltage of ICOMP pin is
OC
P
V
S
, R
N
RSNS
=
to obtain more flexibility. Assume the voltage across
(
(
, which is given by Equation 20:
=
, the maximum voltage of ICOMP pin is determined
IS1
I
N
O
V
. Since the current sense resistance changes
O
)
⋅
, R
V
)
⋅
R
–
+
-
N
–
--------------------- -
R
+
ICOMP(max)
SNS
V
V
IS2
S
V
O
R
(OPTIONAL)
O
N
+
P
R
=
R
⋅
=
should be adjusted to meet the
P
⎛
⎜
⎝
P
1
I
I
OC
OC
R
+
S
R
------------ -
R
⋅
⋅
R
IS2
IS1
R
- V
SNS
SNS
⎞
⎟
⎠
O
V
⋅
) > 25mV.
RSNS
⋅
SNS
--------------------- -
R
⎛
⎜
⎝
P
1
S
R
+
to form a voltage divider
+
P
and the overcurrent set
R
------------ -
R
R
IS2
IS1
P
⋅
⎛
⎜
⎝
⎞
⎟
⎠
1
ICOMP
+
R
------------ -
R
IS2
IS1
⎞
⎟
⎠
July 31, 2008
is given
(EQ. 23)
(EQ. 19)
(EQ. 20)
(EQ. 21)
(EQ. 22)
IS2
FN6745.0
S
and