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)

OVER

)

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

OVER

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

OVER

T

Output Low Voltage — — 0.4 V I

OVER

SOURCE
SINK

Absolute Accuracy — TH+10 — °C At Trip Point
Trip Point Hysteresis — 5 — °C

OVER

=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.

OVER

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

OVER

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

OVER

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

OVER

is at or near the T
falls through the T
maintains the T

is asserted. Built-in hysteresis prevents

OVER

from “chattering” when measured temperature

+ 10°C trip point. As t emperature

H

+ 10°C trip point, hysteresis

H

output low until measured

OVER

temperature is 5°C above the trip point setting.

)