ISL6260CRZ Intersil, ISL6260CRZ Datasheet - Page 20

• Manufacturer Part Number: ISL6260CRZ
• Description: IC CORE REG MULTIPHASE 40-QFN
• Manufacturer: Intersil

Specifications of ISL6260CRZ

• Applications: Converter, Intel IMVP-6
• Number Of Outputs: 1
• Voltage - Output: 0.3 ~ 1.5 V
• Operating Temperature: -10°C ~ 100°C
• Mounting Type: Surface Mount
• Package / Case: 40-VFQFN, 40-VFQFPN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -

determined using the following relationship, where Rfset is in
kΩ and the switching period is in μs.
In discontinuous conduction mode, (DCM), the ISL6260,
ISL6260B runs in period stretching mode. It should be noted
that the switching frequency in the Electric Table is tested
with the error amplifier output or Comp pin voltage at 2V.
When Comp pin voltage is lower, the switching frequency will
not be at the tested value.
Voltage Regulator Thermal Throttling
lntel
processor to prevent catastrophic thermal damage to the
voltage regulator. The ISL6260 and ISL6260B feature a
thermal monitor which senses the voltage change across an
externally placed negative temperature coefficient (NTC)
thermistor, see Figure 41. Proper selection and placement of
the NTC thermistor allows for detection of a designated
temperature rise by the system.
Figure 41 shows the thermal throttling feature with
hysteresis. At low temperature, SW1 is on and SW2
connects to the 1.18V side. The total current going from NTC
pin is 60µA. The voltage on NTC pin is higher than threshold
voltage of 1.18V and the comparator output is low. VR_TT#
is pulling up high by the external resistor.
When temperature increases, the NTC resistor on NTC pin
decreases. The voltage on NTC pin decreases to a level
lower than 1.18V. The comparator changes polarity and
turns SW1 off and throws SW2 to 1.20V. This pulls VR_TT#
low and sends the signal to start thermal throttle. There is a
6µA current reduction on NTC pin and 20mV voltage
increase on threshold voltage of the comparator in this state.
The VR_TT# signal will be used to change the CPU
operation and decrease the power consumption. When the
temperature goes down, the NTC thermistor voltage will
Rfset kΩ
V
FIGURE 41. CIRCUITRY ASSOCIATED WITH THE THERMAL
NTC
®
+
-
(
IMVP-6
R
R
NTC
NTC
s
)
=
(
THROTTLING FEATURE OF THE ISL6260
®
Period μs
1.20V
technology supports thermal throttling of the
54µA
(
) 0.29
SW2
–
6µA
SW1
20
1.18V
+
-
)
×
2.33
INTERNAL TO
ISL6260
ISL6260, ISL6260B
(EQ. 4)
VR_TT#
eventually go up. If NTC voltage increases to 1.20V, the
comparator will then be able to flip back. The external
resistance difference in these two conditions is:
Therefore, proper NTC thermistor has to be chosen such
that 2.56K resistor change will be corresponding to required
temperature hysteresis. Regular external resistor may need
to be in series with NTC resistors to meet the threshold
voltage values.
The following is an example.
For Panasonic NTC with B = 4700, its resistance will drop to
0.03322 of its nominal at 105°C, and drop to 0.03956 of its
nominal at 100 C°. If the requirement for the temperature
hysteresis is (105-100) C°, the required resistance of NTC
will be:
Therefore a larger value thermistor, such as 470 K NTC
should be used.
At 105°C, 470K NTC resistance becomes
(0.03322*470K) = 15.6K. With 60µA on NTC pin, the voltage
is only (15.6K*60µA) = 0.937V. This value is much lower
than the threshold voltage of 1.18V. Therefore, a resistor is
needed to be in series with the NTC. The required resistance
can be calculated by:
4.02K is a standard resistor value. Therefore, the NTC
branch should have a 470K NTC and 4.02K resistor in
series. The part number for the NTC thermistor is
ERTJ0EV474J. It is a 0402 package. NTC thermistor will be
placed in the hot spot of the board. A thermistor in an 0402
package costs less than in an 0603 package.
1
60
54
(
1
.
0
18
2 .
.
μ
uA
03956
V
A
V
−
−
2
1
.
15
60
56
.
18
−
μ
.
K
6
0
A
V
K
Ω
.
03322
Ω
=
2
=
.
56
4
.
)
06
K
=
K
404
Ω
K
Ω
January 3, 2006
FN9162.1