TC650/TC651
Tiny Integrated Temperature Sensor & Brushless DC Fan
Controller with Overtemperature Alert
Features
General Description
• Integrated Temperature Sensing and Multi-speed
Fan Control
• Built-in Overtemperature Alert (TOVER)
• Temperature-proportional Fan Speed Control for
Acoustic Noise Reduction and Longer Fan Life
• Pulse Width Modulation (PWM) Output Drive for
Cost and Power Savings
• Solid-state Temperature Sensing
• ±1C (typ.) Accuracy from 25C to +70C
• Operating Range: 2.8V – 5.5V
• TC651 includes Automatic Fan Shutdown
• Low Operating Current: 50 µA (typ.)
The TC650/TC651 are integrated temperature sensors
and brushless DC fan speed controllers. The TC650/
TC651 measure the junction temperature and control
the speed of the fan based on that temperature, making
them especially suited for applications in modern
electronic equipment.
Applications
•
•
•
•
•
•
Thermal Protection For Personal Computers
Digital Set-Top Boxes
Notebook Computers
Data Communications
Power Supplies
Projectors
Related Literature
• Application Note 771 (DS00771)
Temperature data is converted from the on-chip
thermal 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 temperature limits to control the fan. The
TC650/TC651 also include a single trip point overtemperature alert (TOVER) that eliminates the need for
additional temperature sensors. In addition, the TC651
features an auto fan shutdown function for additional
power savings.
The TC650/TC651 are easy to use, require no software
overhead and are, therefore, the ideal choice for
implementing thermal management in a variety of
systems.
Package Type
8-Pin MSOP
VDD 1
NC 2
SHDN 3
GND 4
2001-2012 Microchip Technology Inc.
8 PWM
TC650
TC651
7 GND
6 TOVER
5 NC
DS21450D-page 1
TC650/TC651
Typical Application Circuit
+12V
PIC®
Microcontroller
+5V VDD
SHDN
Control
DC Fan
500 mA
TC650
TC651
1 VDD
PWM 8
2 NC
GND 7
3 SHDN
4 GND
CSLOW
TOVER 6
NC 5
GND
GND
Overtemperature
Alert
DS21450D-page 2
2001-2012 Microchip Technology Inc.
TC650/TC651
1.0
ELECTRICAL
CHARACTERISTICS
Absolute Maximum Ratings†
Input Voltage (VDD to GND) ................................... +6V
† Notice: Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device.
These are stress ratings only and functional operation of the
device at these or any other conditions above those indicated
in the operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affect device reliability.
Output Voltage (OUT to GND) ................................. 6V
Voltage On Any Pin ....... (GND – 0.3V) to (VDD + 0.3V)
Operating Temperature Range ......... –40C to +125C
Storage Temperature ........................ –65C to +150C
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise specified, VDD = 2.8V to 5.5V, SHDN = VDD, TA = –40C to +125C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Supply Voltage
VDD
2.8
—
5.5
V
Supply Current
IDD
—
50
90
µA
SHDN Input High Threshold
VIH
65
—
—
%VDD
SHDN Input Low Threshold
VIL
—
—
15
%VDD
PWM Output Low Voltage
VOL
—
—
0.3
V
ISINK = 1 mA
PWM Output High Voltage
VOH
VDD – 0.5
—
—
V
ISOURCE = 5 mA
PWM Rise Time
tR
—
10
—
µs
IOH = 5 mA, 1 nF from
PWM to GND
PWM Fall Time
tF
—
10
—
µs
IOL = 1 mA, 1 nF from
PWM to GND
fOUT
10
15
—
Hz
tSTARTUP
—
32/fOUT
—
sec
PWM, TOVER are open
SHDN Input
PWM Output
PWM Frequency
Start-up Time
VDD Rises from GND
or SHDN Released
Temperature Accuracy
High Temperature Accuracy
TH ACC
TH – 3
TH
TH + 3
°C
Note 1
–1.0
—
+1.0
°C
(TH – TL) 20C
–2.5
—
+2.5
°C
(TH – TL) 20C
THYST
—
(TH -TL)/5
—
°C
TC651 Only
TOVER Output High Voltage
VHIGH
VDD – 0.5
—
—
V
ISOURCE = 1.2 mA
TOVER Output Low Voltage
VLOW
—
—
0.4
V
ISINK = 2.5 mA
Absolute Accuracy
TOVER ACC
—
TH + 10
—
°C
At Trip Point
Trip Point Hysteresis
TOVER HYST
—
5
—
°C
Temperature Range Accuracy (TH –TL) ACC
Auto-shutdown Hysteresis
TOVER Output
Note 1:
Transition from 90% to 100% Duty Cycle.
2001-2012 Microchip Technology Inc.
DS21450D-page 3
TC650/TC651
TEMPERATURE CHARACTERISTICS
Electrical Specifications: Unless otherwise noted, VDD = 2.8V to 5.5V, SHDN = VDD, TA = -40C to +125C.
Parameters
Sym
Min
Typ
Max
Units
Specified Temperature Range
TA
–40
—
+125
°C
Maximum Junction Temperature
TJ
—
—
+150
°C
Storage Temperature Range
TA
–65
—
+150
°C
JA
—
206.3
—
°C/W
Conditions
Temperature Ranges
Package Thermal Resistances
Thermal Resistance, 8L-MSOP
DS21450D-page 4
2001-2012 Microchip Technology Inc.
TC650/TC651
2.0
TYPICAL PERFORMANCE CURVES
Note:
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note: Unless otherwise indicated, VDD = 2.8V to 5.5V, SHDN = VDD, TA = –40C to +125C.
90
3.0
80
2.5
VDD = 5.6
60
IDD (µA)
Temp Accuracy (°C)
70
50
40
VDD = 2.7
30
20
2.0
1.5
1.0
VDD = 5.6
0.5
10
0.0
0
-50 -25
0
50
25
75 100 125 150
VDD = 2.7
T1
TL
T2
FIGURE 2-1:
IDD vs. Temperature.
FIGURE 2-4:
VTH.
500
1.0
450
0.9
400
VDD - VOH (V)
VOL (mV)
300
VDD = 5.5V
250
200
150
100
50
0.0
T4
TH
Temperature Accuracy vs.
0.8
VDD = 2.8V
350
T3
TTHRESHOLD
TEMPERATURE (°C)
0.7
VDD = 2.8V
0.6
VDD = 5.5V
0.5
0.4
0.3
0.2
TA = +25°C
0
1
2
3
4
5
6
7
8
9
10
0.1
0.0
ISINK (mA)
FIGURE 2-2:
PWM, ISINK vs. VOL.
FIGURE 2-5:
(VDD – VOH).
TA = +25°C
0
2
4
6
8 10 12 14 16 18 20
ISOURCE (mA)
PWM, ISOURCE vs.
1.0
0.9
VDD = 2.8V
VDD - VOH (V)
0.8
0.7
0.6
VDD = 5.5V
0.5
0.4
0.3
0.2
TA = +25°C
0.1
0.0
0
1
2
3
4
5
6
7
8
9
10
ISOURCE (mA)
FIGURE 2-3:
(VDD – VOH).
TOVER, ISOURCE vs.
2001-2012 Microchip Technology Inc.
DS21450D-page 5
TC650/TC651
3.0
PIN DESCRIPTION
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
Pin No.
Symbol
1
VDD
Power Supply Input
2
NC
No Internal Connect
3
SHDN
4
GND
5
NC
6
TOVER
7
GND
Ground
8
PWM
PWM Fan Drive Output
3.1
Description
Fan Shutdown, Active-low Input
1 = Fan in normal operation
0 = Fan in shutdown
Ground
No Connect
Overtemperature Alert, Active-low Output
1 = Overtemperature condition does not exist
0 = The device is in the overtemperature condition. The fan is driven at 100%.
Potential exists for system over-heating
Power Supply Input
3.4
Overtemperature Alert
May be independent of fan power supply.
Active-low output.
3.2
3.5
Fan Shutdown, Active-low Input
During Shutdown mode, the chip still monitors
temperature. TOVER is low if temperature rises above
factory set point.
3.3
PWM Fan Drive Output
Pulse width modulated rail-to-rail logic output. Nominal
frequency is 15 Hz.
Ground
Ground return for all TC650/TC651 functions.
DS21450D-page 6
2001-2012 Microchip Technology Inc.
TC650/TC651
4.0
DETAILED DESCRIPTION
4.2
The TC650/TC651 acquire and convert their junction
temperature (TJ) information from an on-chip, solidstate sensor with a typical accuracy of ±1°C. 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 41). The TC650/TC651 control 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 300 mA. For larger current fans (up
to 1 amp), a logic-level N-channel MOSFET may be
used. In addition to controlling the speed of the fan, the
TC650/TC651 include an on-chip overtemperature
alarm (TOVER) that gives a low signal when the temperature of the chip exceeds TH by 10°C (typical). This feature eliminates the need for a separate temperature
sensor for overtemperature monitoring. Figure 4-1
shows the block diagram of the device.
TOVER
VDD
Temperature
Set Point and
Trim Range
V+
SHDN
Duty Cycle
Logic
Control
PWM
A/D Converter
Oscillator
Temperature Sensor
FIGURE 4-1:
4.1
Functional Block Diagram.
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. 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 15 Hz. The PWM is also the time base for the
Start-up Timer (see Section 4.2 “Start-Up Timer”).
The PWM duty cycle has a range of 40% to 100% for
the TC650 and 50% to 100% for the TC651.
2001-2012 Microchip Technology Inc.
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.
4.3
Overtemperature Alert (TOVER)
This pin goes low when the TH set point is exceeded by
10°C (typical). 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 be used to either
trigger system shutdown or bring other fans in the
system to full speed. The fan will continue to run at full
speed while TOVER is asserted. Built-in hysteresis
prevents TOVER from “chattering” when the measured
temperature is at or near the TH + 10°C trip point. As
temperature falls through the TH + 10°C trip point, hysteresis maintains the TOVER output low until the
measured temperature is 5°C above the trip point
setting.
4.4
Shutdown (SHDN)
The fan can be unconditionally shut down by pulling
the SHDN pin low. During shutdown, the PWM output
is low; ideal for notebook computers and other portable
applications where you need to change batteries and
must not have the fan running at that time. Thermal
monitoring and TOVER are still in operation during
shutdown. IDD shutdown current is around 50 µA.
4.5
Auto-shutdown Mode
The TC651 features auto-shutdown. When the
temperature is below the factory set point at minimum
speed (TL), PWM is low and the fan is automatically
shut off (Auto-shutdown mode). This feature is ideal for
notebook computers and other portable equipment that
need to conserve as much battery power as possible
and, thus, run a fan when it is only absolutely needed.
The TC651 will continue to be active in order to monitor
temperature for TOVER. The TC651 exits Autoshutdown mode when the temperature rises above the
factory set point (T1).
DS21450D-page 7
TC650/TC651
4.6
Temperature Selection Guide
(Minimum Fan Speed/Full Speed)
There are two temperature thresholds that determine
the characteristics of the device. The minimum fan
speed temperature (TL) and the full fan speed temperature (TH). Depending on the TC65X device selected,
when the temperature is below the TL trip point, the
PWM output will perform a different operation. For the
TC650, the PWM will be driven at the minimum PWM
frequency, while the TC651 will shut down the PWM
(PWM = L).
TL and TH can be selected in 5°C increments. TL can
range from 25°C to 35°C. TH can range from 35°C to
55°C and must be 10°C (or more) than the specified TL.
The five temperature regions defined by the six
thresholds are defined in the TC650/TC651 by means of
factory trimming. Once a TL and TH are set, the T1 – T4
thresholds are automatically equally spaced between TL
and TH. Table 4-1 shows these 5 regions and what the
corresponding PWM duty cycle is.
TABLE 4-1:
TC650
(Minimum
Speed mode)
TC651
(Auto-shutdown
mode)
T < TL
40%
Off
TL< = T < T1
50%
50%
T 1 < = T < T2
60%
60%
T2 < = T
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