ISL6316 Intersil Corporation, ISL6316 Datasheet - Page 21

• Manufacturer Part Number: ISL6316
• Description: Enhanced 4-Phase PWM Controller
• Manufacturer: Intersil Corporation

FIGURE 14. BLOCK DIAGRAM OF THERMAL MONITORING
FIGURE 15. THE RATIO OF TM VOLTAGE TO NTC
FIGURE 16. VR_HOT AND VR_FAN SIGNAL VS TM VOLTAGE
o
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c
VR_HOT
VR_FAN
0.39*Vcc
0.33*Vcc
0.28*Vcc
100%
90%
80%
70%
60%
50%
40%
30%
20%
TM
VCC
R
R
TM
TM1
NTC
0
FUNCTION
TEMPERATURE WITH RECOMMENDED PARTS
20
0.33V
0.28V
V
40
TM
Tem perature (
/ V
CC
CC
CC
21
60
T1
vs. Tem perature
T2
80
o
T3
C)
100
Temperature
120
VR_FAN
VR_HOT
140
ISL6316
The NTC resistance at the set point T2 and release point T1
of VR_FAN signal can be calculated as:
With the NTC resistance value obtained from Equations17 &
18, the temperature value T2 and T1 can be found from the
NTC datasheet.
Temperature Compensation
ISL6316 supports inductor DCR sensing, MOSFET R
sensing, or resistive sensing techniques. Both inductor DCR
and MSOFET R
coefficient, which is about +0.38%/°C. Because the voltage
across inductor or MOSFET is sensed for the output current
information, the sensed current has the same positive
temperature coefficient as the inductor DCR or MOSFET
R
In order to obtain the correct current information, there should
be a way to correct the temperature impact on the current
sense component. ISL6316 provides two methods: integrated
temperature compensation and external temperature
compensation.
Integrated Temperature Compensation
When TCOMP voltage is equal or greater than Vcc/15,
ISL6316 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 17.
R
R
o
DS(ON)
NTC T2
NTC T1
c
FIGURE 17. BLOCK DIAGRAM OF INTEGRATED
V
V
CC
CC
(
(
R
R
R
R
TCOMP
NTC
TC2
TM1
TC1
.
)
)
TM
=
=
1.267xR
1.644xR
TEMPERATURE COMPENSATION
DS(ON)
Non-linear
4-bit
A/D
D/A
A/D
NTC T3
NTC T3
have the positive temperature
(
(
)
)
k
i
Over current protection
I
Channel current
4
Droop &
sense
I
3
I
2
August 31, 2005
I
1
DS(ON)
(EQ. 17)
(EQ. 18)
FN9227.0
I
I
I
I
sen4
sen3
sen2
sen1