MICROCHIP TC650, TC651 Technical data

TC650/TC651
Tiny Integrated Temperature Sensor & Brushless DC Fan
Controller with Over-Temperature Alert
Features
• Integrated TemperatureSensing and Multi-speed Fan Control
• Built-in Over Temperature Alert (T
• Temperature Proportional Fan Speed Control for Acoustic Noise Reduction and Longer Fan Life
• PulseWidthModulationOutputDrivefor Cost and Power Savings
• Solid-State Temperature Sensing
•±1°C (Typical) Accuracy from 25°Cto+70°C
• 2.8V – 5.5V Operating Range
• TC651 includesAuto Fan Shutdown
• Low Operating Current: 50µA(Typical)
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Applications
• Thermal Protection For Personal Computers
• Digital Set-Top Boxes
• Notebook Computers
• Data Communications
• Power Supplies
•Projectors
Related Literature
• ApplicationNote: AN771
Device Selection Table
Part Number Package
TC650XXVUA 8-PinSOIC -40°Cto+125°C TC651XXVUA 8-PinM SOP -40°Cto+125°C
Temperature
Range
Package Type
8-Pin MSOP 8-Pin SOIC
V
DD
NC
SHDN
GND
1
2
3
4
TC650 TC651
8
7
6
5
PWM
GND
T
OVER
NC
General Description
The TC650/TC651 are integrated temperaturesensors and brushless DC fan speed controllers. The TC650/ TC651 measure their junction temperature and control thespeedofthefanbasedonthattemperature,making them especially suited for applications in modern electronic equipment.
Temperature data is converted from the on-chip thermal sensing element and translated into a fractionalfan speed from 40% to 100%. A temperature selection guide i n 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 over temperature alert (T additionaltemperature sensors. In addition, the TC651 features an auto fan shutdown function for additional power savings.
The TC650/TC651are easy to use, requireno software overhead and are therefore the ideal choice for implementing thermal management in a variety of systems.
) that eliminates the need for
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XTemperature
A25 B30 C35 D40 E45 F50 G55
The "X" denotes a suffix for temperature threshold settings. Contact factory for other temperature ranges.
2002 Microchip TechnologyInc. DS21450B-page 1
TC650/TC651
Typical Application Diagram
+5V V
DD
TC650 TC651
+12V
DC Fan
500mA
1
2
3
4
GND
V
DD
NC
SHDN
GND
SHDN Control
PWM
GND
T
OVER
µController
8
7
6
NC
5
Over-Temp. Alert
C
SLOW
GND
DS21450B-page 2
2002 Microchip TechnologyInc.
TC650/TC651
1.0 ELECTRICAL
CHARACTERISTICS
*Stresses above those listed under "Absolute Maximum Rat­ings"maycause permanentdamage to thedevice.These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the
Absolute Maximum Ratings*
Input Voltage (VDDto GND)...................................+6V
operation sections of the specifications is not implied. E xpo­sure to Absolute Maximum R ating conditions for extended periodsmay affectdevice reliability.
Output Voltage (OUT to GND) .................................6V
Voltage On Any Pin.......(GND – 0.3V) to (V
Package Thermal Resistance (θ
) ..............250°C/W
JA
DD
+0.3V)
Operating Temperature Range ..........-40°Cto+125°C
Storage Temperature .........................-65°Cto+150°C
TC650/TC651 EL ECTRI CAL SPECIFICATIONS
Electrical Characteristics: VDD= 2.8V to 5.5V, SHDN =VDD,TA=-40°Cto125°C unlessotherwise specified. Symbol Parameter Min Typ. Max Units Test Conditions
V
DD
I
DD
SHDN
V
IH
V
IL
PWM Output
V
OL
V
OH
t
R
t
F
f
OUT
t
STARTUP
Temperature Accuracy
T
H ACC
(T
H –TL) ACC
T
HYST
T
OVER
V
HIGH
V
LOW
T
OVER ACC
T
OVER HYST
Note 1: Transition from 90% to 100% Duty Cycle.
Supply Voltage 2.8 5.5 V Supply Current 50 90 µAPWM,T
Input
SHDN Input High Threshold 65 %V SHDN Input Low Threshold 15 %V
PWM Output Low Voltage 0.3 V I PWM Output HighVoltage VDD-0.5 V I
DD DD
SINK SOURCE
PWM Rise Time 10 µsec IOH=5mA,1nFfrom
PWM to GND
PWM Fall Time 10 µsec IOL=1mA,1nFfrom
PWM to GND PWM Frequency 10 15 H z Start-upTime 32/f
High Temperature Accuracy TH–3 T
OUT
H
—secVDDRises from GND,
or S HDN
TH+3 °C Note1
Temp. Range Accuracy -1.0 +1.0 °C(TH-TL) 20°C
-2.5 +2.5 °C(T
H-TL
Auto-shutdown Hysteresis (TH-TL)/5 °CTC651Only
Output
T
Output High Voltage VDD-0.5 V I
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T
Output Low Voltage 0.4 V I
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SOURCE SINK
Absolute Accuracy TH+10 °C At Trip Point Trip Point Hysteresis 5 °C
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=1mA
=5mA
Released
) 20°C
=1.2mA
=2.5mA
are open
2002 Microchip TechnologyInc. DS21450B-page 3
TC650/TC651
2.0 PIN DESCRIPTIONS
ThedescriptionsofthepinsarelistedinTable2-1.
TABLE 2-1: PIN FUNCTION TABLE
Pin No.
(8-Pin MSOP)
(8-Pin SOIC)
1V 2 NC No Internal Connect. 3 SHDN
4 GND Ground. Ground return for all TC650/TC651 functions. 5 NC No Connect. 6T 7 GND Ground. 8 PWM PWM Fan Drive Output. Pulse width modulated rail-to-rail logic output. Nominal
Symbol Description
DD
OVER
Power Supply Input. May be independent of fan power supply.
Fan Shutdown, Active-Low Input. During Shutdown mode the chip still monitors temper­ature and T
Over-Temperature Alert, Active-Low Output.
Frequency is 15Hz.
is low if temperature rises above factory set point.
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DS21450B-page 4
2002 Microchip TechnologyInc.
TC650/TC651
3.0 DETAILED DESCRIPTION
The TC650/TC651 acquire and convert their junction temperature (T 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 t emperatures (see Table 3-1 and Table 3-2). The TC650/TC651 control the speed of a DC brushless fan using a fractional speed control scheme.The output stage requiresonly 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 may be used. In addition to controlling the speed of the fan, the TC650/TC651 include an on-chip over-temperature alarm (T when the temperatureof the chip exceeds T (typical).Thisfeature eliminatest he need for a separate temperature sensor for over-temperature monitoring.
TABLE 3-1: TEMPERATURE RANGE
Temperature (T = T
T
L
T
1
T
2
T
3
T
4
<=T<T
T
H
T
) information from an on-chip solid-state
J
) thatgives a low signal
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DEFINITION FOR T C650 (MINIMUM-SPEED MODE)
) PWM Duty Cycle
J
T<T
L
<=T<T
<=T<T
<=T<T
<=T<T
<=T<T
OV
1
2
3
4
H
OV
< = T 100% wi th OverTempAlert
(T
40% 50% 60% 70% 80% 90%
100%
OVER
=L)
by 10°C,
H
FIGURE 3-1: FUNCTIONAL BLOCK
DIAGRAM
V
DD
Temperature Set Point and
Trim Range
A/D Converter
Temperature Sensor
T
OVER
SHDN
Duty Cycle
Logic
Control
Oscillator
V+
PWM
3.1 PWM Output
The PWM pin is designed to drive a low cost transistor or MOSFET as thelow 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, t he 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 time base for the Start-up Timer (see paragraphs below). The PWM duty cycle has a range of 40% to 100% for the TC650 and 50% to 100% for the TC651.
3.2 Start-Up Timer
To ensure reliable fan start-up,the Start-upTimerturns 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.
TABLE 3-2: TEMPERATURE RANGE
DEFINITION FOR T C651 (AUTO-SHUTDOWN MODE)
Temperature (T = T
T<T
L
<=T<T
T
L
<=T<T
T
1
<=T<T
T
2
<=T<T
T
3
<=T<T
T
4
<=T<T
T
H
< = T 100% withOver-TempAlert
T
OV
Note:The temperature regions defined by the six temperature thresh­olds are pre-defined in the TC650/TC651 by means of trimming. Once aT
andTHare programmed, the T1–T4thresholds are automatically
L
equally spaced between T
2002 Microchip TechnologyInc. DS21450B-page 5
) PWM Duty Cycle
J
1
2 3 4
H
OV
(T
OVER
and TH.
L
“OFF”
50% 60% 70% 80% 90%
100%
=L)
3.3 Over-Temperature Alert (T
This pin goes low whenthe THset point is exceeded by
o
10
C (typical). This indicates that the fan is at
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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 t rigger system shutdown, or bring other fans to f ull speed in the system. The f an will continue to run at 100% speed while T T
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is at or near the T falls through the T maintains the T
is asserted. Built-in hysteresis prevents
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from “chattering” when measured temperature
+ 10°C trip point. As t emperature
H
+ 10°C trip point, hysteresis
H
output low until measured
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temperature is 5°C above the trip point setting.
)
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