ISL6334ACRZ Intersil, ISL6334ACRZ Datasheet - Page 23

• Manufacturer Part Number: ISL6334ACRZ
• Description: IC CTRLR PWM 4PHASE BUCK 40-QFN
• Manufacturer: Intersil

Specifications of ISL6334ACRZ

• Applications: Controller, Intel VR11.1
• Voltage - Input: 3 ~ 12 V
• Number Of Outputs: 1
• Voltage - Output: 0.5 ~ 1.6 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 40-VFQFN, 40-VFQFPN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Based on the NTC temperature characteristics and the
desired threshold of the VR_HOT signal, the pull-up resistor
RTM1 of TM pin is given by Equation 18:
R
temperature T3.
R
FIGURE 14. VR_HOT AND VR_FAN SIGNAL vs TM VOLTAGE
NTC(T3)
FIGURE 12. BLOCK DIAGRAM OF THERMAL MONITORING
TM1
FIGURE 13. THE RATIO OF TM VOLTAGE TO NTC
VR_HOT
VR_FAN
o
0.451*Vcc
0.391*Vcc
0.333*Vcc
c
TM
=
100
VCC
R
90
80
70
60
50
40
30
20
2.75xR
R
TM
TM1
is the NTC resistance at the VR_HOT threshold
0
NTC
FUNCTION
TEMPERATURE WITH RECOMMENDED PARTS
NTC T3
20
(
0.391V
0.333V
40
)
TEMPERATURE (°C)
CC
CC
T1
60
23
T2
80
T3
100
TEMPERATURE
120
VR_FAN
VR_HOT
ISL6334, ISL6334A
140
(EQ. 18)
The NTC resistance at the set point T2 and release point T1 of
VR_FAN signal can be calculated as shown in Equations 19
and 20:
With the NTC resistance value obtained from Equations 19
and 20, the temperature value T2 and T1 can be found from
the NTC datasheet.
Temperature Compensation
The ISL6334, ISL6334A supports inductor DCR sensing, or
resistive sensing techniques. The inductor DCR has a
positive temperature coefficient, which is about +0.385%/°C.
Since the voltage across inductor is sensed for the output
current information, the sensed current has the same
positive temperature coefficient as the inductor DCR.
In order to obtain the correct current information, there
should be a way to correct the temperature impact on the
current sense component. ISL6334, ISL6334A provides two
methods: integrated temperature compensation and external
temperature compensation.
Integrated Temperature Compensation
When the TCOMP voltage is equal or greater than VCC/15,
ISL6334, ISL6334A will utilize the voltage at TM and
TCOMP pins to compensate the temperature impact on the
sensed current. The block diagram of this function is shown
in Figure 15..
When the TM NTC is placed close to the current sense
component (inductor), the temperature of the NTC will track
the temperature of the current sense component. Therefore
the TM voltage can be utilized to obtain the temperature of
the current sense component.
R
R
o
FIGURE 15. BLOCK DIAGRAM OF INTEGRATED
c
NTC T2
NTC T1
V
V
CC
CC
(
(
R
R
R
R
TCOMP
NTC
TC2
TM1
TC1
)
)
TM
=
=
1.267xR
1.644xR
TEMPERATURE COMPENSATION
NON-LINEAR
4-BIT
D/A
A/D
NTC T3
NTC T3
A/D
(
(
)
)
k
i
I
4
OVERCURRENT
PROTECTION
DROOP AND
CHANNEL
CURRENT
SENSE
I
3
I
2
May 28, 2009
I
(EQ. 19)
(EQ. 20)
1
FN6482.1
I
I
I
I
sen4
sen3
sen2
sen1