Integrated Temperature Sensor and
Brushless DC Fan Controller with Fan
Fault Detect and Over Temperature Alert
TC652
TC652
TC653
TC653
Integrated Temperature Sensor and Brushless DC Fan
Controller with Fan Fault Detect and Over Temperature Alert
FEATURES
s
s
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Digital Temperature Sensing and Multi-Speed
Fan Control
FanSense
™
Fan Fault Detect Circuitry
Built in Over Temperature Alert (Tover)
Temperature Proportional Fan Speed Control for
Acoustic Noise Reduction and Longer Fan Life
Pulse Width Modulation Output Drive for Cost
and Power Savings
Solid State Temperature Sensing
±
1
o
C (Typical) Accuracy from 25
o
C to +70
o
C
2.8 -5.5V Operating Range
TC653 includes Auto Fan Shutdown
Low Operating Power: 50
µ
A (Typ)
GENERAL DESCRIPTION
The TC652/653 are integrated temperature sensors
and brushless DC fan speed controllers with FanSense™
technology. The TC652/653 measure their junction tem-
perature and control the speed of the fan based on that
temperature, making them especially suited for applications
in modern electronic equipment. The FanSense
™
fan fault
detect circuitry eliminates the need for a more expensive
3 wire fan.
Temperature data is converted from the on-chip ther-
mal sensing element and translated into a fractional fan
speed from 40% to 100%. A temperature selection guide in
the data sheet is used to choose the low and high side
temperature limits that correlate fan speed with tempera-
ture. The TC652/653 also include a single trip point over
temperature alert (Tover) that eliminates the need for addi-
tional temperature sensors. In addition the TC653 includes
an auto fan shutdown function for additional power savings.
The TC652/653 are easy to use, require no software
overhead, and are therefore the ideal choice for implement-
ing thermal management in a variety of systems.
FanSense™ is a trademark of TelCom Semiconductor, Inc.
APPLICATIONS
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Thermal Protection for Personal Computers
Digital Set-Top Boxes
Notebook Computers
Data Communications
Power Supplies
Projectors
RELATED LITERATURE
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Application Note: 58
Article: "An integrated fan speed control solution
can lower system costs, reduce acoustic noise
and power consumption and enhance system
reliability"
ORDERING INFORMATION
Part
Number
TC652XXVUA
TC653XXVUA
X
A
B
C
D
E
F
G
Package
8-Pin MSOP
8-Pin MSOP
25
30
35
40
45
50
55
Operating
Temp. Range
–40˚C to +125˚C
–40˚C to +125˚C
Temperature
TYPICAL APPLICATION
+12V
+5V V
DD
1KΩ
1
2
3
4
VDD
FAULT TC652
TC653
SHDN
GND
PWM
GND
Tover
SENSE
DC FAN
300mA
MAX
8
7
6
0.01µF
5
C
SENSE
R
SENSE
Notes:
1. The "X" denotes a suffix for temperature threshold settings.
2. Please see the Temperature Selection Guide on page 5
3. Contact factory for other temperature ranges.
PIN CONFIGURATIONS
8-Pin MSOP
VDD 1
FAULT 2
SHDN 3
GND 4
8 PWM
GND
SHDN CONTROL
FAN FAULT ALERT
OVER TEMP
ALERT
2Ω
TC652
TC653
7 GND
6 Tover
5 SENSE
µController
TC652/3-1 5/23/00
TelCom Semiconductor reserves the right to make changes in the circuitry and specifications of its devices.
1
Integrated Temperature Sensor and
Brushless DC Fan Controller with Fan
Fault Detect and Over Temperature Alert
TC652
TC653
ABSOLUTE MAXIMUM RATINGS*
Input Voltage (V
DD
to GND) ....................................... +6V
Output Voltage (OUT to GND) ......................................6V
Voltage On Any Pin ............ (GND – 0.3V) to (V
DD
+ 0.3V)
Package Thermal Resistance (θ
JA
)
......................
250
o
C/W
Operating Temperature Range .............. –40
o
C to +125
o
C
Storage Temperature (unbiased) .......... –65
o
C to +150
o
C
Lead Temperature
(Soldering, 10sec duration) ............................. +300
o
C
* This is a stress rating only and functional operation of the device at these
or any other conditions above those indicated in the operation section of
this specification is not implied. Exposure to absolute maximum ratings
conditions for extended periods of time may affect reliability.
ELECTRICAL CHARACTERISTICS:
V
DD
= 2.8V to 5.5V, SHDN = V
DD
, T
A
= -40˚C to 125˚C unless otherwise specified.
Symbol
V
DD
I
DD
V
IH
V
IL
V
OL
V
OH
t
R
t
F
f
OUT
t
STARTUP
V
TH (sense)
Parameter
Supply Voltage
Supply Current
SHDN Input High Threshold
SHDN Input Low Threshold
PWM Output Low Voltage
PWM Output High Voltage
PWM Rise Time
PWM Fall Time
PWM Frequency
Startup Time
Sense Input
Test Conditions
PWM, FAULT, Tover are open
Min
2.8
—
65
—
Typ
—
50
—
—
—
—
10
10
15
32/f
OUT
70
Max
5.5
90
—
15
0.3
—
—
—
—
—
—
Units
V
µA
%V
DD
%V
DD
V
V
µsec
µsec
Hz
sec
mV
SHDN Input
PWM Output
I
SINK
= 1mA
I
SOURCE
= 5mA
I
OH
= 5mA, 1nF from PWM to GND
I
OL
= 1mA, 1nF from PWM to GND
V
DD
Rises from GND, or SHDN Released
Sense Input Threshold Voltage with
Respect to Ground
Note 1
(T
H
– T
L)
≤
20°C
(T
H
– T
L)
> 20°C
TC653 Only
I
SOURCE
= 1.2mA
I
SINK
= 2.5mA
—
V
DD
– 0.5
—
—
10
—
—
Temperature Accuracy
T
H ACC
High Temp Accuracy
(T
H
–T
L)ACC
Temp Range Accuracy
T
H
– 3
–1.0
–2.5
—
V
DD
– 0.5
—
—
T
H
—
—
(T
H
– T
L
)/5
—
—
32/f
OUT
T
H
+ 3
+1.0
+2.5
—
—
0.4
—
°C
°C
°C
V
V
sec
T
HYST
Auto Shutdown Hysteresis
FAULT Output
V
HIGH
V
LOW
tmp
FAULT Output High Voltage
FAULT Output Low Voltage
Missing Pulse
Detector Timeout
Tover Output High Voltage
Tover Output Low Voltage
Absolute Accuracy
Trip Point Hysteresis
Tover Output
V
HIGH
V
LOW
Tover
ACC
Tover
HYST
Notes:
I
SOURCE
= 1.2mA
I
SINK
= 2.5mA
At Trip Point
V
DD
– 0.5
—
—
—
—
—
T
H
+ 10
5
—
0.4
—
—
V
V
°C
°C
1. Transition from 90% to 100% Duty Cycle.
TC652/3-1 5/23/00
2
Integrated Temperature Sensor and
Brushless DC Fan Controller with Fan
Fault Detect and Over Temperature Alert
TC652
TC653
PIN DESCRIPTION
Pin No.
1
2
Symbol
V
DD
FAULT
Description
Power Supply Input. May be independent of fan power supply.
Fan Fault Alert, Active-Low Output. Fault goes low to indicate a fan fault condition. When
Fault ocurrs, the device is latched in shutdown mode with PWM low. Toggling the
SHDN pin or cycling the V
DD
will release the part and fan from shutdown. Fault will
unconditionally remain high during shutdown.
Fan Shutdown, Active-Low Input. During shut down mode the chip still monitors temp-
erature and Tover is low if temperature rises above factory setpoint.
Ground return for all TC652/653 functions.
Detect Fan Pulses Input. Pulses are detected at this pin as fan rotation chops the current
through the sense resistor, Rsense. The absense of pulses indicates a fan fault.
Over-Temperature Alert, Active-Low Output.
Ground.
PWM Fan Drive Output. Pulse width modulated rail-to-rail logic output. Nominal
frequency is 15Hz.
3
4
5
6
7
8
SHDN
GND
SENSE
Tover
GND
PWM
FUNCTONAL BLOCK DIAGRAM
V
DD
TEMPERATURE
SET POINT AND
TRIM RANGE
V+
TOVER
SHDN
DUTY
CYCLE
LOGIC
CONTROL
PWM
AD CONVERTER
OSCILLATOR
TEMP SENSOR
FAULT
FAN DETECT
LOGIC
+
CMPTR
SENSE
may be used. In addition to controling the speed of the fan,
the TC652/653 include an on-chip over-temperature alarm
(Tover) that gives a low-true signal when the temperature of
the chip exceeds T
H
by 10°C. This feature eliminates the
need for a separate temperature sensor for over-tempera-
ture monitoring.
In normal fan operation, a pulse train is present at
SENSE, pin 5. A missing-pulse detector monitors this pin
during fan operation (FanSense™). A stalled, open, or
unconnected fan causes the TC652/653 to trigger its startup
timer once. If the fault persists, the FAULT output goes low,
and the device is latched in its Shutdown Mode. To release
the fan from shutdown, toggle the SHDN or V
DD
Pin.
Table 1. Temperature Range Definition for TC652
(Minimum-Speed Mode)
Temperature (T=Tj)
T<T
L
T
L
<=T<T
1
T
1
<=T<T
2
T
2
<=T<T
3
T
3
<=T<T
4
T
4
<=T<T
H
T
H
<=T<T
OV
T
OV
<=T
–
20K
90mV
PWM Duty Cycle
FUNCTIONAL DESCRIPTION
The TC652/653 acquire and convert their junction tem-
perature (Tj), information from an on-chip solid state sensor
with a typical accuracy of
±1
o
C (typical) . The temperature
data is digitally stored in an internal register. The register is
compared with pre-defined threshold values. The six
threshold values are equally distributed over a pre-defined
range of temperatures (See Table 1). The TC652/653 con-
trol the speed of a DC brushless fan using a fractional speed
control scheme. The output stage requires only a 2N2222-
type small-signal BJT for fans up to 300mA. For larger
current fans (up to 1 Amp) a logic-level N-channel MOSFET
TC652/3-1 5/23/00
40%
50%
60%
70%
80%
90%
100%
100% with over temp Alert (Tover = L)
3
Integrated Temperature Sensor and
Brushless DC Fan Controller with Fan
Fault Detect and Over Temperature Alert
TC652
TC653
Table 2. Temperature Range Definition for TC653
(Auto-Shutdown Mode)
Temperature (T=Tj)
T<T
L
T
L
<=T<T
1
T
1
<=T<T
2
T
2
<=T<T
3
T
3
<=T<T
4
T
4
<=T<T
H
T
H
<=T<T
OV
T
OV
<=T
PWM Duty Cycle
waveform on R
SENSE
is differentiated and converted to a
logic-level pulse train by C
SENSE
and the internal signal
processing circuitry. The presence and frequency of this
pulse-train is a direct indication of fan operation.
“OFF”
50%
60%
70%
80%
90%
100%
100% with over temp Alert (Tover = L)
FAULT
This pin goes low to indicate a fan fault condition. Pulses
appearing at SENSE pin due to the PWM turning on are
blanked and the remaining pulses are filtered by a missing
pulse detector. If consecutive pulses are not detected for 32
PWM cycles (about 2 sec), the PWM is Low and FAULT
goes low. FAULT can be disabled by momentarily toggling
SHDN or V
DD
pin, or cycling system power. FAULT remains
high during Shutdown Mode.
Note:
The temperature regions defined by the six temperature thresholds
are pre-defined in the TC652/653 by means of trimming. Once a T
L
and T
H
are programmed, the T
1
– T
4
thresholds are automatically equally spaced
between T
L
and T
H
.
Over-Temperature Alert (Tover)
DETAILED DESCRIPTION
PWM Output
The PWM pin is designed to drive a low-cost transistor
or MOSFET as the low-side power-switching element in the
system. Various examples of driver circuits will be shown
below. This output has an asymmetric complementary drive
and is optimized for driving NPN-transistors or N-channel
MOSFETs. Since the system relies on PWM rather than
linear power control, the dissipation in the power switch is
kept to a minimum. Generally, very small devices (TO-92 or
SOT packages) will suffice. The frequency of the PWM is
about 15Hz. The PWM is also the timebase for the Start-up
Timer (see paragraphs below). The PWM duty cycle has a
range of 40% to 100% for the TC652 and 50% to 100% for
the TC653.
This pin goes low when the T
H
set point is exceeded by
10 C. This indicates that the fan is at maximum drive, and
the potential exists for system overheating: either heat
dissipation in the system has gone beyond the cooling
system's design limits, or some fault exists such as fan
bearing failure or an airflow obstruction. This output may be
treated as a “System Overheat” warning and used to trigger
system shutdown, or bring other fans to full speed in the
system. The fan will continue to run at 100% speed while
Tover is asserted. Built-in hysteresis prevents Tover from
“chattering” when measured temperature is at or near the
T
H
+ 10
o
C trip point. As temperature falls through the
T
H
+ 10
o
C trip point, hysteresis maintains the Tover output
low until measured temperature is 5
o
C above the trip point
setting.
o
Start-Up Timer
To ensure reliable fan start-up, the Start-up Timer turns
PWM high for about 2 seconds whenever the fan is started
from the off state. This occurs at power-up and when coming
out of Shutdown Mode.
Shutdown (SHDN)
The fan can be unconditionally shutdown by pulling low
the SHDN pin. During shutdown FAULT output is high and
PWM output is low. This is ideal for notebook computer and
other portable applications when you need to change batter-
ies and must not have the fan running at the time. Thermal
monitoring and Tover are still in operation during shutdown.
I
DD
shutdown current is around 50µA.
SENSE Input (FanSense™)
The SENSE input, pin 5, is connected to a low-value
current sensing resistor in the ground return leg of the fan
circuit. During normal fan operation, commutation occurs as
each pole of the fan is energized. This causes brief interrup-
tions in the fan current, seen as pulses across the sense
resistor. If the device is not in Shutdown mode, and pulses
are not appearing at the SENSE input, a fault exists. The
short, rapid change in fan current (high di/dt) causes a
corresponding dv/dt across the sense resistor, R
SENSE
. The
TC652/3-1 5/23/00
Auto-Shutdown Mode
The TC653 has auto shutdown. If the temperature is
below the factory set point at minimum speed (T
L
), PWM is
low and the fan is automatically shut off (Auto-Shutdown
mode). This feature is ideal for notebook computers and
other portable applications that need to conserve as much
battery power as possible and thus run a fan when it is only
absolutely needed. The TC653 will continue to be active so
4
Integrated Temperature Sensor and
Brushless DC Fan Controller with Fan
Fault Detect and Over Temperature Alert
TC652
TC653
as to monitor temperature for Tover. The TC653 exits Auto-
Shutdown mode when the temperature rises above the
factory set point (T
1
).
+12V
Temperature Selection Guide
(Minimum Fan Speed/Full Speed)
The five temperature regions defined by the six thresh-
olds are defined in the TC652/653 by means of factory
trimming. Once a T
L
and T
H
are set, the T
1
– T
4
thresholds
are automatically equally spaced between T
L
and T
H
.
Temp Range
(
°
C)
10
+5V V
DD
1KΩ
1
2
3
4
VDD
FAULT TC652
TC653
SHDN
GND
PWM
GND
Tover
SENSE
DC FAN
400mA
MAX
8
7
6
0.01µF
5
C
SENSE
R
SENSE
10µF
C
SLOW
T
L
25
30
35
25
30
35
25
30
35
25
T
H
35
40
45
40
45
50
45
50
55
55
Part #
GND
(
°
C) (
°
C)
AC
BD
CE
AD
BE
CF
AE
BF
CG
AG
SHDN CONTROL
FAN FAULT ALERT
OVER TEMP
ALERT
2Ω
15
µController
Figure 1. Reducing Switching Noise
20
30
Note:
The
Bold Type
temperature settings are available for
ordering. Contact factory for other temperature selections.
T
L
and T
H
can be selected in 5
o
C increments. T
H
must
be chosen at least 10
o
C higher than T
L
. T
L
can range from
25
o
C to 35
o
C.
As an example, suppose you wanted the fan to
run at
40% speed at 25
o
C
or less and go to
full speed at 45
o
C.
You would order the part number TC652AEVUA.
As another example, suppose you wanted the fan to
turn on at 30
o
C
and go to
full speed at 45
o
C.
You would
order the part number TC653BEVUA.
APPLICATIONS INFORMATION
Reducing Switching Noise
For fans consuming more than 300mA, a slowdown
capacitor (C
SLOW
) is recommended for reducing switching
PWM induced noise (see Figure 1). The value of this
capacitor should be 4.7µF to 47µF, depending on the fan
current consumption. Please see Application Note 38 for
more information.
TC652/3-1 5/23/00
5
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