ISL62882HRTZ-T Intersil, ISL62882HRTZ-T Datasheet - Page 23

• Manufacturer Part Number: ISL62882HRTZ-T
• Description: IC REG PWM 2PHASE BUCK 40TQFN
• Manufacturer: Intersil

Specifications of ISL62882HRTZ-T

• Applications: Controller, Intel IMVP-6.5™
• Voltage - Input: 5 V ~ 25 V
• Number Of Outputs: 1
• Voltage - Output: 0.0125 V ~ 1.5 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: *
• Package / Case: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

capacitance. At the beginning of i
capacitance is less because R
of the C
when C
ring back. This effect is more pronounced when C
much larger than C
R
ripple of the V
recommended to keep C
value usually is a few ohms. C
should be determined through tuning the load transient
response waveforms on an actual board.
R
providing a lower impedance path than R
beginning of i
effect at steady state. Through proper selection of R
and C
V
100Ω. C
transient response waveforms on an actual board. The
recommended range for C
it should be noted that the R
the i
real inductor current, i
which may adversely affect i
detection and therefore may affect OCP accuracy. User
discretion is advised.
Resistor Current-Sensing Network
Figure 23 shows the resistor current-sensing network for
a 2-phase solution. Each inductor has a series current-
sensing resistor R
R
information. The R
capacitor C
attenuation. Equations 20 thru 22 give V
FIGURE 23. RESISTOR CURRENT-SENSING NETWORK
o
V
n
ip
sen
RSEN
Cn
DCR
will not ring back. The recommended value for R
is bigger. However, the presence of R
and C
droop
PHASE1
s ( )
L
pads to accurately capture the inductor current
ip
n
n.1
values, i
ip
=
is too small, and this effect will reduce the V
IO
ip
should be determined through tuning the load
waveform. Instead of being triangular as the
R
-------------
RSEN
n
branch. As Figure 19 explains, V
DCR
sen
N
form an R-C branch in parallel with R
. R
PHASE2
o
L
n
×
sum
change. R
signal if C
droop
I
o
sen
s ( )
sum
n.2
and C
. R
×
RSUM
RSUM
can resemble i
. It is also more pronounced when
droop
A
RO
RO
and R
Rsen
sum
n.2
ip
n
n.2
23
ip
form a a filter for noise
and C
s ( )
greater than 2200pF. R
may have sharp spikes,
and R
is 100pF~2000pF. However,
droop
ip
o
n
is too small. It is
n.1
resistors are connected to
-C
increases the impedance
, C
ip
o
ip
o
average value
VCN
change, the effective
do not have any
branch may distort
are connected to the
n.2
o
rather than i
and R
n
Cn
i
increases the
ISL62882, ISL62882B
at the
CN
(s) expression
o
RI
tends to dip
n
values
i
,
(EQ. 20)
ISUM+
ISUM-
n.1
L
n
, and
ip
ip
is
o
is
Transfer function A
Current-sensing resistor R
significant variation over-temperature, so there is no
need for the NTC network.
The recommended values are R
C
Overcurrent Protection
Refer to Equation 1 on page 16 and Figures 12, 17 and
23; resistor R
shows the internal OCP threshold. It is recommended to
design I
For example, the OCP threshold is 40µA for 2-phase
solution. We will design I
so the OCP trip level is 1.16x of the full load current.
For inductor DCR sensing, Equation 23 gives the DC
relationship of V
Substitution of Equation 23 into Equation 1 gives
Equation 24:
Therefore:
Substitution of Equation 15 and application of the OCP
condition in Equation 25 gives Equation 26:
where I
corresponding droop current. For example, given N = 2,
R
DCR = 0.88mΩ, I
Equation 26 gives R
For resistor sensing, Equation 27 gives the DC
relationship of V
R
ω
V
I
R
A
n
sum
V
droop
Rsen
Cn
i
i
Cn
Rsen
= 5600pF.
=
=
=
= 3.65kΩ, R
=
--------------------------------------------------------------------------------- -
N
---------------------------------------------------------------------------------------------------------------------------- -
N
s ( )
=
=
⎛
⎜
⎜
⎜
⎝
×
×
omax
R
-------------
droop
------------------------------------------
R
2
⎛
⎜
⎝
⎛
⎝
sen
N
---- -
R
---------------------------- -
R
-------------- -
2
ntcnet
2R
R
(
----------------------------------------------------
=
×
R
R
i
sum
N
ntcnet
×
R
(
----------------------------------------------------
ntcs
ntcs
---------------------- -
1
×
ntcnet
R
R
------------------------------------------
R
ntcnet
is the full load current, I
1
i
+
without using the R
I
ntcs
ntcs
ntcnet
o
×
sets the droop current I
------------ -
ω
+
1
+
+
cn
cn
C
R
sns
s
R
-------------- -
+
R
R
omax
n
p
ntcnet
×
+
+
(s) and I
sum
(s) and I
R
-------------- -
N
ntc
ntc
Rsen
DCR
R
R
= 11kΩ, R
sum
+
i
N
ntc
ntc
= 998Ω.
) R
R
-------------- -
+
×
×
sum
⎞
⎠
R
= 51A and I
(s) always has unity gain at DC.
N
) R
DCR
-------------
+
×
×
×
p
droop
N
R
p
I
I
sen
o
droop
p
+
×
o
p
o
⎞
⎟
⎟
⎟
⎠
R
-------------- -
(s).
DCR
-------------
(s).
×
×
ntcs
sum
N
N
value will not have
DCR
I
to be 34.3µA at full load,
o
sum
⎞
⎟
⎠
×
comp
= 2.61kΩ, R
×
I
×
o
droopmax
I
I
droopmax
omax
= 1kΩ and
droopmax
droop
resistor.
. Table 4
= 34.3µA,
ntc
is the
= 10kΩ,
(EQ. 21)
(EQ. 22)
(EQ. 23)
(EQ. 24)
(EQ. 25)
(EQ. 26)
(EQ. 27)
FN6890.3