ISL62882HRTZ Intersil, ISL62882HRTZ Datasheet - Page 24

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

Specifications of ISL62882HRTZ

• 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

Substitution of Equation 27 into Equation 1 gives
Equation 28:
Therefore
Substitution of Equation 29 and application of the OCP
condition in Equation 25 gives Equation 30:
where I
corresponding droop current. For example, given N = 2,
R
Equation 30 gives R
A resistor from COMP to GND can adjust the internal OCP
threshold, providing another dimension of fine-tune
flexibility. Table 4 shows the detail. It is recommended to
scale I
approximately the desired OCP level, then use R
fine tune the OCP level if necessary.
Load Line Slope
Refer to Figure 12.
For inductor DCR sensing, substitution of Equation 24
into Equation 2 gives the load line slope expression:
For resistor sensing, substitution of Equation 28 into
Equation 2 gives the load line slope expression:
Substitution of Equation 25 and rewriting Equation 31,
or substitution of Equation 29 and rewriting Equation 32
give the same result in Equation 33:
One can use the full load condition to calculate R
For example, given I
and LL = 1.9mΩ, Equation 33 gives R
It is recommended to start with the R
calculated by Equation 33, and fine tune it on the actual
board to get accurate load line slope. One should record
the output voltage readings at no load and at full load for
load line slope calculation. Reading the output voltage at
lighter load instead of full load will increase the
measurement error.
I
R
R
R
LL
LL
sen
droop
droop
i
i
=
=
=
=
= 1mΩ, I
2R
--------------------------- -
2R
---------------------------------------
N
N
V
------------------ -
V
------------------ -
droop
=
omax
droop
droop
×
×
=
sen
sen
I
I
---- -
R
o
o
I
I
2
droop
droopmax
----------------
I
i
droop
×
×
×
I
such that the default OCP threshold gives
o
R
-------------
=
=
I
I
is the full load current, I
o
omax
omax
sen
N
2R
---------------------- -
2R
------------------------------------------ -
×
LL
×
droop
sen
R
I
i
N
o
= 51A and I
i
omax
= 1.487kΩ.
×
×
R
R
×
droop
i
------------------------------------------
R
ntcnet
24
= 51A, I
R
ntcnet
+
droopmax
R
-------------- -
sum
N
droopmax
droop
droopmax
droop
×
DCR
-------------
N
= 34.3µA,
ISL62882, ISL62882B
= 2.825kΩ.
value
= 34.3µA
is the
droop
comp
(EQ. 33)
(EQ. 28)
(EQ. 29)
(EQ. 30)
(EQ. 31)
(EQ. 32)
.
to
Current Monitor
Refer to Equation 13 for the IMON pin current
expression.
Refer to Figures 1 and 2, the IMON pin current flows
through R
Equation 34:
Rewriting Equation 33 gives Equation 35:
Substitution of Equation 35 into Equation 34 gives
Equation 36:
Rewriting Equation 36 and application of full load
condition gives Equation 37:
For example, given LL = 1.9mΩ, R
V
R
A capacitor C
the IMON pin voltage. The R
the user’s choice. It is recommended to have a time
constant long enough such that switching frequency
ripples are removed.
Compensator
Figure 18 shows the desired load transient response
waveforms. Figure 24 shows the equivalent circuit of a
voltage regulator (VR) with the droop function. A VR is
equivalent to a voltage source (= VID) and output
impedance Z
slope LL, i.e. constant output impedance, in the entire
frequency range, V
has a square change.
Intersil provides a Microsoft Excel-based spreadsheet to
help design the compensator and the current sensing
network, so the VR achieves constant output impedance
as a stable system. Figure 27 shows a screenshot of the
spreadsheet.
FIGURE 24. VOLTAGE REGULATOR EQUIVALENT
V
I
V
R
Rimon
imon
droop
Rimon
Rimon
imon
= 9.358kΩ.
=
=
= 963mV at I
=
=
------------------ -
R
V
----------------------------------------------
imon
3
3I
--------------------- -
VID
droop
Rimon
R
I
×
o
o
droop
out
3I
I
imon
×
droop
. The voltage across R
o
LL
×
(s). If Z
×
×
LL
R
LL
×
Z
can be paralleled with R
out
o
×
droop
R
(s) = LL
R
imon
will have square response when I
omax
imon
out
VR
(s) is equal to the load line
= 51A, Equation 37 gives
imon
i
o
C
droop
imon
LOAD
imon
= 2.825kΩ,
time constant is
is expressed in
imon
V
o
to filter
(EQ. 34)
(EQ. 35)
(EQ. 36)
(EQ. 37)
FN6890.3
o