ISL6263CRZ Intersil, ISL6263CRZ Datasheet - Page 16

• Manufacturer Part Number: ISL6263CRZ
• Description: IC VREG CORE 5BIT 1PHASE 32-QFN
• Manufacturer: Intersil

Specifications of ISL6263CRZ

• 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

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.
The current sensing traces should be routed directly to the
inductor pads for accurate DCR voltage drop measurement.
However, due to layout imperfection, the calculated R
may still need slight adjustment to achieve optimum load line
slope. It is recommended to adjust R
has achieved thermal equilibrium at full load. For example, if
the maximum load current is 20A, one should apply a 20A
load current and look for 160mV output voltage droop. If the
voltage droop is 155mV, the new value of R
calculated by Equation 16:
For the best accuracy, the effective resistance on the DFB
and VSUM pins should be identical so that the bias current
of the droop amplifier does not cause an offset voltage.
Dynamic Droop Capacitor Design Using DCR
Sensing
Figure 10 shows the desired waveforms during load
transient response. V
I
V
of output inductor, output capacitor, compensator design,
and the design of droop capacitor C
If C
an excellent representation of the inductor current. Given the
correct C
I
waveform of the inductor current and worsens the transient
response. Figure 11 shows the transient response when C
is too small allowing V
load transient. Figure 12 shows the transient response when
C
value.
R
core
CORE
CCGFX
N
DRP2new
N
is too large. V
as close as possible. The transient response of
is designed correctly, the voltage V
, if not, its voltage will be distorted from the actual
is determined by several factors, namely the choice
N
design, V
=
160mV
-------------------
155mV
CCGFX
CCGFX
⋅
CCGFX
(
CCGFX
R
DRP1
takes too long to droop to its final
has the best chance of tracking
16
needs to follow the change in
–
to sag excessively during the
R
DPR2
N
DRP2
.
) R
–
DROOP
DRP1
after the system
DRP2
-V
is
O
(EQ. 16)
will be
DRP2
N
ISL6263
The current sensing network consists of R
C
R
needs to match the L/DCR time constant of the inductor to
get the correct representation of the inductor current
waveform. Equation 17 shows this relationship:
Solution of C
For example: L = 0.45µH, DCR = 1.1mΩ, R
R
Since the inductance and the DCR typically have 20% and
7% tolerance respectively, C
-------------
DCR
C
C
FIGURE 10. DESIRED LOAD TRANSIENT RESPONSE
FIGURE 12. LOAD TRANSIENT RESPONSE WHEN C
N
S
NTCEQ
FIGURE 11. LOAD TRANSIENT RESPONSE WHEN C
N
N
L
. The RC time constant of the current sensing network
. The effective resistance is the parallel of R
=
=
=
------------------------------------------- -
⎛
⎜
⎝
------------------------------------------------ -
⎛
⎝
-------------------------------------- -
R
------------------------------------------ -
3.4kΩ
R
3.4kΩ 7.68kΩ
⎛
⎜
⎝
V
V
V
NTCEQ
-------------------------------------- -
R
NTCEQ
R
= 3.4kΩ:
⎛
⎝
⎛
⎝
core
core
core
NTCEQ
NTCEQ
0.45μH
------------------- -
1.1mΩ
-------------
DCR
N
L
+
WAVEFORMS
SMALL
LARGE
⋅
yields Equation 18:
7.68kΩ
+
⎞
⎠
⋅
R
Δ
R
+
⎞
⎠
⋅
S
S
V
R
R
⎞
⎟
⎠
S
S
core
⎞
⎠
⎞
⎟
⎠
=
⋅
C
=
174nF
V
V
V
i
i
i
N
core
core
core
Δ
core
core
core
N
I
core
needs to be fine tuned on the
×
R
droop
Δ
Δ
V
NTCEQ
I
S
core
core
= 7.68kΩ, and
NTCEQ
, R
June 10, 2010
N
N
S
(EQ. 17)
(EQ. 18)
(EQ. 19)
IS TOO
IS TOO
, and
FN9213.2
and