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PDF TC665 Data sheet ( Hoja de datos )
| Número de pieza | TC665 | |
| Descripción | (TC664 / TC665) PWM Fan Speed Controllers | |
| Fabricantes | Microchip Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de TC665 (archivo pdf) en la parte inferior de esta página. Total 30 Páginas | ||
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M
TC664/TC665
SMBus™ PWM Fan Speed Controllers With
Fan Fault Detection
Features
• Temperature Proportional Fan Speed for Reduced
Acoustic Noise and Longer Fan Life
• FanSense™ Protects against Fan Failure and
Eliminates the Need for 3-wire Fans
• Over Temperature Detection (TC665)
• Efficient PWM Fan Drive
• Provides RPM Data
• 2-Wire SMBus™-Compatible Interface
• Supports Any Fan Voltage
• Software Controlled Shutdown Mode for "Green"
Systems
• Supports Low Cost NTC/PTC Thermistors
• Space Saving 10-Pin MSOP Package
• Temperature Range: -40°C to +85ºC
Applications
• Personal Computers & Servers
• LCD Projectors
• Datacom & Telecom Equipment
• Fan Trays
• File Servers
• Workstations
www.DataShee•t4GU.ecnoemral Purpose Fan Speed Control
Package Type
10-Pin MSOP
VIN 1
CF 2
SCLK 3
SDA 4
GND 5
TC664
TC665
10 VDD
9 VOUT
8 SENSE
7 NC
6 FAULT
Description
The TC664/TC665 devices are PWM mode fan speed
controllers with FanSense technology for use with
brushless DC fans. These devices implement temper-
ature proportional fan speed control which lowers
acoustic fan noise and increases fan life. The voltage
at VIN (Pin 1) represents temperature and is typically
provided by an external thermistor or voltage output
temperature sensor. The PWM output (VOUT) is
adjusted between 30% and 100%, based on the volt-
age at VIN. The PWM duty cycle can also be pro-
grammed via SMBus to allow fan speed control without
the need for an external thermistor. If VIN is not con-
nected, the TC664/TC665 will start driving the fan at a
default duty cycle of 39.33%. See Section 4.3, "Fan
Startup", for more details).
In normal fan operation, a pulse train is present at the
SENSE pin (Pin 8). The TC664/TC665 use these
pulses to calculate the fan revolutions per minute
(RPM). The fan RPM data is used to detect a worn out,
stalled, open or unconnected fan. An RPM level below
the user-programmable threshold causes the TC664/
TC665 to assert a logic low alert signal (FAULT). The
default threshold value is 500 RPM. Also, if this condi-
tion occurs, FF (bit 0<0>) in the Status Register will also
be set to a ‘1’.
An over-temperature condition is indicated when the
voltage at VIN exceeds 2.6 V (typical). The TC664/
TC665 devices indicate this by setting OTF(bit 5<X>) in
the Status Register to a '1'. The TC665 device also
pulls the FAULT line low during an over-temperature
condition.
The TC664/TC665 devices are available in a 10-Pin
MSOP package and consume 150 µA during opera-
tion. The devices can also enter a low-power shutdown
mode (5 µA, typ.) by setting the appropriate bit in the
Configuration Register. The operating temperature
range for these devices is -40°C to +85ºC.
SMBus is a trademark of Intel Coporation
2002 Microchip Technology Inc.
DS21737A-page 1
1 page  
TC664/TC665
SMBus Write Timing Diagram
AB
tLOW tHIGH
C
SCLK
SDA
D EE F
G
H IJ K L M
tSU(START) tH(START)
tSU-DATA
tH-DATA
A = Start Condition
B = MSB of Address Clocked into Slave
C = LSB of Address Clocked into Slave
D = R/W Bit Clocked into Slave
E = Slave Pulls SDA Line Low
F = Acknowledge Bit Clocked into Master
G = MSB of Data Clocked into Slave
H = LSB of Data Clocked into Slave
I = Slave Pulls SDA Line Low
tSU(STOP)tIDLE
J = Acknowledge Clocked into Master
K = Acknowledge Clock Pulse
L = Stop Condition, Data Executed by Slave
M = New Start Condition
SMBus Read Timing Diagram
AB
tLOW tHIGH
C
SCLK
SDA
D EF
G
HI
JK
tSU(START) tH(START)
tSU-DATA
A = Start Condition
B = MSB of Address Clocked into Slave
C = LSB of Address Clocked into Slave
D = R/W Bit Clocked into Slave
E = Slave Pulls SDA Line Low
F = Acknowledge Bit Clocked into Master
G = MSB of Data Clocked into Master
H = LSB of Data Clocked into Master
FIGURE 1-1:
www.DataSheet4U.com
Bus Timing Data.
tSU(STOP)
tIDLE
I = Acknowledge Clock Pulse
J = Stop Condition
K = New Start Condition
2002 Microchip Technology Inc.
DS21737A-page 5
5 Page 
4.3 Fan Startup
Often overlooked in fan speed control is the actual
startup control period. When starting a fan from a non-
operating condition (fan speed is zero RPM), the
desired PWM duty cycle or average fan voltage can not
be applied immediately. Since the fan is at a rest posi-
tion, the fan’s inertia must be overcome to get it started.
The best way to accomplish this is to apply the full rated
voltage to the fan for one second. This will ensure that
in all operating environments, the fan will start and
operate properly.
The TC664/TC665 devices implement this fan control
feature without any user programming. During a power
up or release from shutdown condition, the TC664/
TC665 devices force the VOUT output to a 100% duty
cycle, turning the fan full on for one second (CF =
1.0 µF). Once the one second period is over, the
TC664/TC665 devices will look to see if SMBus or VIN
control has been selected in the Configuration Register
(DUTYC bit 5<0>). Based on this register, the device
will choose which input will control the VOUT duty cycle.
Duty cycle control based on VIN is the default state. If
VIN control is selected and the VIN pin is open (nothing
is connected to the VIN pin), then the TC664/TC665 will
default to a duty cycle of 39.33%. This sequence is
shown in Figure 4-4. This integrated one second star-
tup feature will ensure the fan starts up every time.
Power Up or Release
from SHDN
One Second Pulse
www.DataSheet4U.com
Select SMBus
Default PWM: 39.33%
NO
YES
VIN Open?
NO
VIN PWM Duty
Cycle Control
YES
SMBus PWM Duty
Cycle Control
FIGURE 4-4:
Power-up Flow Chart.
4.4 PWM Drive Frequency (CF)
As previously discussed, the TC664/TC665 devices
operate with a fixed PWM frequency. The frequency of
the PWM drive output (VOUT) is set by a capacitor at the
CF pin. With a 1 µF capacitor at the CF pin, the typical
drive frequency is 30 Hz. This frequency can be raised,
by decreasing the capacitor value, or lowered, by
increasing the capacitor value. The relationship
between the capacitor value and the PWM frequency is
TC664/TC665
linear. If a frequency of 15 Hz is desired, a capacitor
value of 2.0 µF should be used. The frequency should
be kept in the range of 15 Hz to 35 Hz. See Section 7.2
for more details.
4.5 Duty Cycle Control (VIN and Duty-
Cycle Register)
The duty cycle of the VOUT PWM drive signal can be
controlled by either the VIN analog input pin or by the
Duty-Cycle Register, which is accessible via the
SMBus interface. The control method is selectable via
DUTYC (bit 5<0>) of the Configuration Register. The
default state is for VIN control. If VIN control is selected
and the VIN pin is open, the PWM duty cycle will default
to 39.33%. The duty cycle control method can be
changed at any time via the SMBus interface.
VIN is an analog input pin. A voltage in the range of
1.62 V to 2.6 V (typical) at this pin commands a 30% to
100% duty cycle on the VOUT output, respectively. If the
voltage at VIN falls below the 1.62 V level, the duty
cycle will not go below 30%. The relationship between
the voltage at VIN and the PWM duty cycle is shown in
Figure 4-5.
100
90
80
70
60
50
40
30
20
10
0
1
1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8
Input Voltage (VIN)
FIGURE 4-5:
PWM Duty Cycle vs. Input
Voltage, VIN (Typical).
For the TC665 device, if the voltage at VIN exceeds the
2.6 V (typical) level, an over temperature fault indica-
tion will be given by asserting a low at the FAULT output
and setting OTF (bit 5<X>) in the Status Register to a
‘1’.
A thermistor network or any other voltage output ther-
mal sensor can be used to provide the voltage to the
VIN input. The voltage supplied to the VIN pin can actu-
ally be thought of as a temperature. For example, the
circuit shown in Figure 4-6 represents a typical solution
for a thermistor based temperature sensing network.
See Section 7.3 for more details.
2002 Microchip Technology Inc.
DS21737A-page 11
11 Page | ||
| Páginas | Total 30 Páginas | |
| PDF Descargar | [ Datasheet TC665.PDF ] | |
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