M
Features
TC642B/TC647B
Description
The TC642B/TC647B devices are new versions of the
existing TC642/TC647 fan speed controllers. These
devices are switch mode, fan speed controllers that
incorporate a new fan auto-restart function. Tempera-
ture-proportional speed control is accomplished using
pulse width modulation. A thermistor (or other voltage
output temperature sensor) connected to the V
IN
input
supplies the required control voltage of 1.20V to 2.60V
(typical) for 0% to 100% PWM duty cycle. Minimum fan
speed is set by a simple resistor divider on the V
MIN
input. An integrated Start-Up Timer ensures reliable
motor start-up at turn-on, coming out of shutdown
mode or following a transient fault. A logic-low applied
to V
MIN
(pin 3) causes fan shutdown.
The TC642B and TC647B also feature Microchip
Technology's proprietary FanSense
™
technology for
increasing system reliability. In normal fan operation, a
pulse train is present at SENSE (pin 5). A missing-
pulse detector monitors this pin during fan operation. A
stalled, open or unconnected fan causes the TC642B/
TC647B device to turn the V
OUT
output on full (100%
duty cycle). If the fault persists (a fan current pulse is
not detected within a 32/f period), the FAULT output
goes low. Even with the FAULT output low, the V
OUT
output is on full during the fan fault condition in order to
attempt to restart the fan. FAULT is also asserted if the
PWM reaches 100% duty cycle (TC642B only), indicat-
ing that maximum cooling capability has been reached
and a possible overheating condition exists.
The TC642B and TC647B devices are available in 8-pin
plastic MSOP, SOIC and PDIP packages. The specified
temperature range of these devices is -40 to +85ºC.
PWM Fan Speed Controllers With Minimum Fan Speed,
Fan Restart and FanSense™ Technology for Fault Detection
• Temperature-Proportional Fan Speed for Acoustic
Noise Reduction and Longer Fan Life
• Efficient PWM Fan Drive
• 3.0V to 5.5V Supply Range:
- Fan Voltage Independent of TC642B/TC647B
Supply Voltage
- Supports any Fan Voltage
• FanSense
™
Fault Detection Circuit Protects
Against Fan Failure and Aids System Testing
• Shutdown Mode for "Green" Systems
• Supports Low Cost NTC/PTC Thermistors
• Over-Temperature Indication (TC642B only)
• Fan Auto-Restart
• Space-Saving 8-Pin MSOP Package
Applications
•
•
•
•
•
•
Personal Computers & Servers
LCD Projectors
Datacom & Telecom Equipment
Fan Trays
File Servers
General Purpose Fan Speed Control
Package Types
MSOP, PDIP, SOIC
V
IN
1
C
F
2
V
MIN
3
GND 4
TC642B
TC647B
8
7
6
5
V
DD
V
OUT
FAULT
SENSE
2003 Microchip Technology Inc.
DS21756B-page 1
TC642B/TC647B
1.0
ELECTRICAL
CHARACTERISTICS
PIN FUNCTION TABLE
Name
V
IN
C
F
V
MIN
GND
SENSE
FAULT
V
OUT
V
DD
Function
Analog Input
Analog Output
Analog Input
Ground
Analog Input
Digital (Open-Drain) Output
Digital Output
Power Supply Input
Absolute Maximum Ratings †
Supply Voltage (V
DD
) .......................................................6.0V
Input Voltage, Any Pin................(GND - 0.3V) to (V
DD
+0.3V)
Operating Temperature Range ....................- 40°C to +125°C
Maximum Junction Temperature, T
J
........................... +150°C
ESD Protection on all pins ........................................... > 3 kV
†
Notice:
Stresses above those listed under “Maximum
Ratings” may cause permanent damage to the device. This is
a stress rating only and functional operation of the device at
those or any other conditions above those indicated in the
operational listings of this specification is not implied. Expo-
sure to maximum rating conditions for extended periods may
affect device reliability.
ELECTRICAL SPECIFICATIONS
Electrical Specifications:
Unless otherwise specified, all limits are specified for -40°C < T
A
< +85°C, V
DD
= 3.0V to 5.5V.
Parameters
Supply Voltage
Supply Current, Operating
Supply Current, Shutdown Mode
V
OUT
Output
Sink Current at V
OUT
Output
Source Current at V
OUT
Output
V
IN
, V
MIN
Inputs
Input Voltage at V
IN
or V
MIN
for 100%
PWM Duty Cycle
Over-Temperature Indication
Threshold
Over-Temperature Indication
Threshold Hysteresis
V
C(MAX)
- V
C(MIN)
Minimum Speed Threshold
Voltage Applied to V
MIN
to Ensure
Shutdown Mode
Voltage Applied to V
MIN
to Release
Shutdown Mode
Hysteresis on V
SHDN
, V
REL
V
IN
, V
MIN
Input Leakage
Pulse-Width Modulator
PWM Frequency
Note 1:
2:
f
PWM
26
30
34
Hz
C
F
= 1.0 µF
Ensured by design, tested during characterization.
For V
DD
< 3.7V, t
STARTUP
and t
MP
timers are typically 13/f.
V
C(MAX)
V
OTF
V
OTF-HYS
V
C(SPAN)
V
MIN
V
SHDN
V
REL
V
HYST
I
IN
1.3
V
C(MAX)
-
V
C(SPAN)
—
V
DD
x 0.19
—
- 1.0
—
—
0.03 x V
DD
—
2.45
2.60
V
C(MAX)
+
20 mV
80
1.4
1.5
V
C(MAX)
V
DD
x 0.13
—
—
+1.0
2.75
V
V
mV
V
V
V
V
V
µA
Note 1
V
DD
= 5V
For TC642B Only
For TC642B Only
I
OL
I
OH
1.0
5.0
—
—
—
—
mA
mA
V
OL
= 10% of V
DD
V
OH
= 80% of V
DD
Sym
V
DD
I
DD
I
DD(SHDN)
Min
3.0
—
—
Typ
—
200
30
Max
5.5
400
—
Units
V
µA
µA
Pins 6, 7 Open,
C
F
= 1 µF, V
IN
= V
C(MAX)
Pins 6, 7 Open,
C
F
= 1 µF, V
MIN
= 0.35V
Conditions
2003 Microchip Technology Inc.
DS21756B-page 3
TC642B/TC647B
ELECTRICAL SPECIFICATIONS (CONTINUED)
Electrical Specifications:
Unless otherwise specified, all limits are specified for -40°C < T
A
< +85°C, V
DD
= 3.0V to 5.5V.
Parameters
SENSE Input
SENSE Input Threshold Voltage with
Respect to GND
Blanking time to ignore pulse due to
V
OUT
turn-on
FAULT Output
Output Low Voltage
Missing Pulse Detector Timer
Start-Up Timer
Diagnostic Timer
Note 1:
2:
V
OL
t
MP
t
STARTUP
t
DIAG
—
—
—
—
—
32/f
32/f
3/f
0.3
—
—
—
V
sec
sec
sec
I
OL
= 2.5 mA
Note 2
Note 2
V
TH(SENSE)
t
BLANK
50
—
70
3.0
90
—
mV
µsec
Sym
Min
Typ
Max
Units
Conditions
Ensured by design, tested during characterization.
For V
DD
< 3.7V, t
STARTUP
and t
MP
timers are typically 13/f.
TEMPERATURE SPECIFICATIONS
Electrical Characteristics:
Unless otherwise noted, all parameters apply at V
DD
= 3.0V to 5.5V
Parameters
Temperature Ranges:
Specified Temperature Range
Operating Temperature Range
Storage Temperature Range
Thermal Package Resistances:
Thermal Package Resistance, 8-Pin MSOP
Thermal Package Resistance, 8-Pin SOIC
Thermal Package Resistance, 8-Pin PDIP
θ
JA
θ
JA
θ
JA
—
—
—
200
155
125
—
—
—
°C/W
°C/W
°C/W
T
A
T
A
T
A
-40
-40
-65
—
—
—
+85
+125
+150
°C
°C
°C
Symbol
Min
Typ
Max
Units
Conditions
DS21756B-page 4
2003 Microchip Technology Inc.
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