ISL6263AIRZ Intersil, ISL6263AIRZ Datasheet - Page 15

• Manufacturer Part Number: ISL6263AIRZ
• Description: IC PWN CTRLR SYNC BUCK 32QFN
• Manufacturer: Intersil

Specifications of ISL6263AIRZ

• Applications: Converter, Intel IMVP-6
• Voltage - Input: 5 V ~ 25 V
• Number Of Outputs: 1
• Voltage - Output: 0.41 V ~ 1.29 V
• Operating Temperature: -40°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 32-VFQFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The NTC network resistor value is dependent on
temperature and is given by Equation 9:
G
temperature of the NTC thermistor shown in Equation 10:
The inductor DCR is a function of temperature and is
approximately given by Equation 11:
The droop amplifier output voltage divided by the total load
current is given by Equation 12:
R
temperature coefficient of the copper. To make R
independent of the inductor temperature, it is desired to
have:
where G
temperature characteristics G
R
G
DCR T ( )
R
G
G
droop
N
1
droop
1
1
1
, the gain of V
T ( )
T ( )
T ( )
T ( )
⋅
=
=
=
(
is the actual load line slope, and 0.00393 is the
=
1
1target
=
-------------------------------
R
-------------------------------------------------------------------- -
(
(
----------------------------------------------------------------------- -
R
+
G
1
R
N
DCR
NTC
0.00393
NTC
R
1
+
T ( )
T ( ) DCR
N
0.00393
T ( )
is the desired ratio of V
+
+
25°C
+
⋅
N
G
FIGURE 8. EQUIVALENT MODEL FOR DROOP CIRCUIT USING INDUCTOR DCR CURRENT SENSING
R
R
R
1t
S
NTCS
to V
NTCS
⋅
(
arg
⋅
⋅
T 25°C
(
25°C
(
1
–
T 25°C
DCR
et
+
–
) R
+
⋅
0.00393
R
⋅
, is also dependent on the
(
NTCP
NTCP
1
1
15
)
+
)
is described by Equation 14:
)
≅
0.00393
)
G
OCP
⋅
(
1t
T 25°C
arg
n
–
−
+
+
−
/ V
et
⋅
(
10µA
DCR
T 25°C
–
)
)
. Therefore, the
DROOP
droop
)
) k
−
+
⋅
(EQ. 10)
(EQ. 13)
(EQ. 14)
(EQ. 11)
(EQ. 12)
DROOP
OCSET
droopamp
(EQ. 9)
VSUM
VDD
DFB
VO
ISL6263A
R
OCSET
It is recommended to begin your droop design using the
R
evaluation board available from Intersil.
The gain of the droop amplifier circuit is shown in Equation 15:
After determining R
Equation 16 to calculate the droop resistances R
R
R
typically 1kΩ.
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.
To see whether the NTC network successfully compensates
the DCR change over-temperature, one can apply full load
current and wait for the thermal steady state and see how
much the output voltage deviates from the initial voltage
reading. A good compensation can limit the drift to less than
2mV. If the output voltage is decreasing when the temperature
increases, that ratio between the NTC thermistor value and
the rest of the resistor divider network has to be increased.
Following the evaluation board value and layout of NTC
placement will minimize the engineering time.
k
R
droopamp
NTC
DRP2
droop
DRP2
, R
.
is 8mΩ per Intel IMVP-6+ specification and R
=
NTCS
⎛
⎜
⎝
⎛
⎜
⎝
=
------------------------------------------ -
DCR G
1
, and R
+
R
R
-------------------
R
⋅
droop
DRP2
DRP1
S
1 25°C
(
and R
NTCP
R
S
)
NTCEQ
⎞
⎟
⎠
NTCEQ
component values of the
–
1
⎞
⎟
⎠
⋅
V
R
DCR
network is sensitive to the
DRP1
networks, use
DRP1
July 8, 2010
DRP1
(EQ. 15)
(EQ. 16)
FN9284.3
and
is