FSCT07A-UH5 STMicroelectronics, FSCT07A-UH5 Datasheet - Page 7

• Manufacturer Part Number: FSCT07A-UH5
• Description: IC CONTROLLER FAN SPEED IPPAK
• Manufacturer: STMicroelectronics
• Type: 18 Line 3-5 Volt Low Capacitance SCSI Active Terminatorr

Specifications of FSCT07A-UH5

• Applications: Fan Controller
• Number Of Outputs: 1
• Voltage - Supply: 9 V ~ 15 V
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: IPPAK-5
• Product: Fan / Motor Controllers / Drivers
• Operating Supply Voltage: 7 V
• Supply Current: 3 mA
• Mounting Style: Through Hole
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output: -
• Voltage - Load: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Fig. 8: Temperature evolution cases in mode OFF.
3. Internal temperature sensor
3.1 Temperature sensor linear response
FSCT devices feature an internal temperature sensor. This sensor results directly from silicon properties. It
is actually a voltage reference which is proportional to the absolute temperature, as it is an image of the Sili-
con thermal voltage "Vt" (refer to the following equation).
This sensing method, which presents a positive temperature coefficient of +2mV/°C is preferred to a V
sensing method (-2mV/°C, sometimes used in thermal protections) because of its better accuracy (low im-
pact of process dispersions).
This signal is then processed to provide the desired OUT voltage range.
This internal sensor allows users not to use a Negative Temperature Coefficient thermistor (NTC).
Hence, users get rid of Joule effect, due to NTC bias current, that disturbs the temperature measurement.
Furthermore, the FSCT response is linear with the temperature. This simplifies the thermal study and the
heat sink rating for the power supply components or for the microprocessor.
NTC thermistors users need also to add a fixed resistor in order to get a linear thermal response from such
kind of sensor. The linear behavior is also only ensured for a restricted temperature range.
3.2 IPPAK mounting considerations
First, it should be noted that the tab is directly connected to the GND pin; then care must be taken when the
FSCT is glued to a heatsink. If this heatsink is at a differential voltage that the Ground, an electrical insula-
tor has to be added between the tab and the heat-sink.
Using non-isolated Through-Hole package like the IPPAK offers also a lot of benefits, compared to NTC
bulbs. Indeed, NTC do not offer a flat area like IPPAK package. Users need to add some glue to ensure
contact of the NTC bulb and the heat sink, at the cost of an increase in the thermal impedance and
response.
T
T
OFF
ON
T
j
Vt
k T
q
with:
3
T absolute temperature K
k Boltzmann cons
q
:
:
. 16 10
19
C
T
P
2
tan
t
( )
1
Time
FSCTxxA-UH5
7/6
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