ISL6263BHRZ Intersil, ISL6263BHRZ Datasheet - Page 14

• Manufacturer Part Number: ISL6263BHRZ
• Description: IC DC/DC BUCK CTRLR 1PH 32-QFN
• Manufacturer: Intersil

Specifications of ISL6263BHRZ

• Applications: Converter, Intel IMVP-6
• Voltage - Input: 5 ~ 25 V
• Number Of Outputs: 1
• Voltage - Output: 0.41 ~ 1.29 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 32-VQFN Exposed Pad, 32-HVQFN, 32-SQFN, 32-DHVQFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The first step in droop load line compensation is to adjust
R
appears even at light loads between the VSUM and VO pins.
As a rule of thumb, the voltage drop V
network, is set to be 0.3 to 0.8 times V
defined as G
signal from which to derive the droop voltage.
The NTC network resistor value is dependent on
temperature and is given by Equation 9:
G
temperature of the NTC thermistor:
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:
R
G
R
G
DCR T ( )
NTCEQ
droop
N
1
droop
1
1
, the gain of V
T ( )
T ( )
T ( )
⋅
=
=
(
is the actual load line slope, and 0.00393 is the
=
1
, and R
-------------------------------
R
(
----------------------------------------------------------------------- -
=
R
+
G
R
N
NTC
0.00393
NTC
R
1
DCR
T ( )
1
T ( ) DCR
N
, provides a reasonable amount of light load
T ( )
+
+
S
+
⋅
25°C
N
FIGURE 8. EQUIVALENT MODEL FOR DROOP CIRCUIT USING INDUCTOR DCR CURRENT SENSING
R
R
R
such that the correct droop voltage
S
NTCS
to V
NTCS
⋅
(
⋅
T 25°C
25°C
(
–
DCR
1
) R
+
+
⋅
R
0.00393
⋅
, is also dependent on the
(
NTCP
NTCP
1
14
)
+
)
≅
0.00393
G
OCP
⋅
1t
(
T 25°C
arg
−
+
+
−
–
N
DCR
et
⋅
across the R
(
10μA
T 25°C
. This gain,
–
)
)
DROOP
↓
droop
)
) k
−
+
⋅
NTCEQ
(EQ. 10)
(EQ. 13)
(EQ. 12)
DROOP
(EQ. 11)
OCSET
droopamp
(EQ. 9)
VSUM
VDD
DFB
VO
ISL6263B
R
OCSET
where G
the temperature characteristics G
Equation 14:
It is recommended to begin your droop design using the
R
evaluation board available from Intersil.
The gain of the droop amplifier circuit is expressed 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.
G
k
R
droopamp
NTC
DRP2
droop
DRP2
1
T ( )
, R
=
.
is 8mΩ per Intel IMVP-6+ specification and R
=
1target
NTCS
-------------------------------------------------------------------- -
(
1
⎛
⎜
⎝
⎛
⎜
⎝
=
+
------------------------------------------ -
DCR G
0.00393
1
, and R
+
is the desired ratio of V
R
R
-------------------
R
G
⋅
droop
DRP2
DRP1
1t
S
1 25°C
arg
⋅
(
and R
NTCP
(
R
T 25°C
et
S
–
)
NTCEQ
⎞
⎟
⎠
NTCEQ
component values of the
–
1
⎞
⎟
⎠
)
)
⋅
V
R
1
DCR
network is sensitive to the
DRP1
is described by
networks, use
n
/ V
DCR
. Therefore,
DRP1
July 8, 2010
DRP1
(EQ. 15)
(EQ. 14)
(EQ. 16)
FN6388.3
and
is