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PDF FSCT07A-UH5 Data sheet ( Hoja de datos )

Número de pieza FSCT07A-UH5
Descripción FAN SPEED CONTROLER
Fabricantes STMicroelectronics 
Logotipo STMicroelectronics Logotipo



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No Preview Available ! FSCT07A-UH5 Hoja de datos, Descripción, Manual

®
A.S.D.TM
Application Specific Discretes
FSCTxxA-UH5
FAN SPEED CONTROLER
APPLICATIONS
s COMPUTER AND SERVER POWER SUPPLY
s TELECOM
s LOW COST VENTILATION (consumer)
FEATURES
s Built in thermal sensor
s Brushless DC fan speed control
s Linear control and regulation of the fan speed
according to the temperature
s Green OFF mode operation with automatic
turn- ON in case of overtemperature
s Voltage limitation above fan stall voltage
s No external NTC required
BENEFITS
s Low cost integrated fan speed control
s High integration: only one or two external com-
ponents
s Reduced acoustic noise because of the linear
control of the external transistor
s Power supply noise rejection
s Good thermal coupling with heater
s Reduced ON/OFF oscillation because of large
hysteresis
s High current capability (base current higher
than 10 mA)
s Higher accuracy than discrete circuit with NTC
1
IPPAK
5
Fig. 1: Block Diagram.
FSCTxxA-UH5
ON
VCC
VOLTAGE
REF.
TEMP.
SENSOR
ON/OFF
LOW
ON/OFF
HIGH
HYSTERESIS
COMPARATOR
ON
REGULATION
HYST.-EN
VT
DRIVER
BIAS
F
OUT
COUT=
100nF
GND
GENERAL DESCRIPTION
The FSCTxxA-UH5 is a high-integrated low cost fan speed controller suitable for PC desktops, notebooks
and server power supplies and also all kind of equipments where low cost ventilation system is needed. An
internal thermal sensor connected to the tab is used to regulate the fan speed. A continuous analog voltage
proportional to the tab temperature is produced at the OUT terminal and can control linearly an external
PNP transistor (Fan Transistor) connected in series with a Brushless DC Fan, in order to vary its speed.
The ON control terminal can be used to select two operation modes. If not connected (high impedance
state) ON mode is selected by default.
In Mode ON, the fan speed is regulated according to the tab temperature of the FSCT by adjusting the Vbe
voltage of the PNP fan Transistor. In low temperature conditions, the fan transistor voltage is limited to
about 5.5V (for a 12V fan) in order to guarantee a minimum voltage across the fan above its stalling voltage
and to keep it running (see figure 3).
This regulation is implemented with a high Fan supply voltage rejection.
www.DatTaShheeemt4oUd.ecoOmFF allows to operate in green Mode. The fan is stopped as long as the temperature remains
below the TON threshold. When the temperature rises above TON the fan is forced to ON and the speed is
regulated according to the temperature as in the same way as mode ON. When temperature falls below
TOFF, the fan is automatically turned OFF. The hysteresis has been dimensioned large enough to reduce
ON/OFF oscillations during the green mode operation.
September 2003 - Ed: 2A
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1 page




FSCT07A-UH5 pdf
FSCTxxA-UH5
DETAILED DESCRIPTION & APPLICATION INFORMATION
1. OUTPUT CHARACTERISTIC VERSUS TEMPERATURE
1.1 FAN speed control
As it's well known, BRUSHLESS DC motors present the advantage of a quasi-linear speed-voltage char-
acteristic. Hence, the fan speed is varying linearly versus the voltage which is applied across its terminals.
The FSCT Integrated Circuit provides at its OUT terminal, a voltage which changes versus the temperature
sensed through its tab. This OUT voltage decreases as temperature increases, following two modes of op-
eration. By connecting this OUT terminal to the Base of a PNP transistor, as shown in figure 1, the FAN
voltage will increase with the sensed temperature.
The FAN voltage is given by the following equation:VFAN = VFAN + VEB VOUT (1)
Typically, for a 12 V VFAN+ and a 1 V VEB voltage, this gives:VFAN (V ) = 11 VOUT (V ) (2)
It can be noticed that the PNP operates as a linear amplifier. This avoids EMI and acoustic noise compared
to Pulse Width Modulation control circuits.
1.2 ON/OFF Mode Selection
The figure 6 gives the algorithm flowchart of the FSCT behavior. First, two modes of operation are distin-
guished by the ON pin signal.
s Mode ON: activated when ON pin is at High Level or Not Connected (thanks to an internal Pull-up
curren source "IS")
s Mode OFF: activated when ON pin is at Low Level.
During Mode ON, the OUT voltage follows a three-parts characteristic, according to its junction tempera-
ture (Tj):
s Tj < TMS: in this case, VOUT is limited to VOMS to avoid stalling the fan rotor
s TMS < Tj < TOL: VOUT is linearly regulated versus the junction temperature
s Tj > TOL: in this case, VOUT is clamped to its minimum value (VOL).
During Mode OFF, an Hysteresis control allows
the system to switch to mode ON only if the tem-
perature exceeds the TON value. The Fan is turned
back off, if the system is cooled enough to lower
the temperature below TOFF.
The figure 7 sums up the FSCT Output character-
istic versus the temperature, for the two operation
modes.
1.3 Minimum speed (mode ON)
Mode ON allows users to ensure that the FAN will
be always ON, whatever the ambient temperature
is.
The OUT voltage is clamped to VOMS for low tem-
perature (below TMS = 37 °C typically).
The VOMS has been set to 5.5 V max , thus the
minimum voltage applied across the FAN is 5.5 V
(according to Equation 2). This voltage is above
stalling value of most fans and will then ensure that
the controlled FAN will always run, in mode ON,
www.DatalaoSvwhoeideteitn4mUgp.scepormuartiuorues.
turn-off due to too
Annoying noises
low voltage at
due to FAN
repetitive starts up are also suppressed.
Fig. 6: FSCT behavior flow-chart.
BEGIN
ON is
LOW
?
no
yes
FAN ON
VOUT = VOMS – kSL.(Tj – TMS)
OR
VOUT = VOMS IF Tj < TMS
OR
VOUT = VOL IF Tj > TOL
FAN OFF (V OUT = VCC)
Tj > TON
?
yes
no
FAN ON
VOUT = VOMS – kSL.(Tj – TMS)
OR
VOUT = VOL IF Tj > TOL
Tj < TOFF
?
yes
FAN OFF
VOUT = VCC
no
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FSCT07A-UH5 arduino
PACKAGE MECHANICAL DATA
IPPAK
FSCTxxA-UH5
E
B2
H L1
L
e
G1
G
L2
B3
B
B6
V1
B5
A1
A
C2
D
C
DIMENSIONS
REF. Millimeters
Inches
Min. Typ. Max Min. Typ. Max.
A 2.20
2.40 0.086
0.094
A1 0.90
1.10 0.035
0.043
B 0.40
0.60 0.015
0.023
B2 5.20
5.40 0.204
0.212
B3 0.70 0.027
B5 0.30
0.011
B6 1.00 0.039
C 0.45
0.60 0.017
0.023
C2 0.48
0.60 0.018
0.023
D 6.00
6.20 0.236
0.244
E 6.40
6.60 0.215
0.259
e 1.27
0.050
G 4.9
5.25 0.192
0.206
G1 2.38
2.70 0.093
0.106
H 15.90
16.30 0.625
0.641
L 9.00
9.40 0.354
0.370
L1 0.80
1.20 0.031
0.047
L2
0.80 1.00
0.031 0.039
V1 10°
10°
Order code
FSCT17A-UH5
FSCT11A-UH5
FSCT07A-UH5
Marking
FSCT17A
FSCT11A
FSCT07A
Package
IPPAK
Weight Delivery mode Base qty
0.4 g
Tube
75
Information furnished is believed to be accurate and reliable. However, STMicroelectronics assumes no responsibility for the consequences of
use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by
implication or otherwise under any patent or patent rights of STMicroelectronics. Specifications mentioned in this publication are subject to
change without notice. This publication supersedes and replaces all information previously supplied. STMicroelectronics products are not au-
thorized for use as critical components in life support devices or systems without express written approval of STMicroelectronics.
The ST logo is a registered trademark of STMicroelectronics.
All other names are the property of their respective owners.
© 2003 STMicroelectronics - All rights reserved.
STMicroelectronics GROUP OF COMPANIES
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