2002-2013 Microchip Technology Inc.
DS21756C-page 1
TC642B/TC647B
Features
• 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
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.
MSOP, PDIP, SOIC
1
2
3
4
V
DD
5
6
7
8
V
OUT
SENSE
V
IN
C
F
V
MIN
GND
FAULT
TC642B
TC647B
PWM Fan Speed Controllers With Minimum Fan Speed,
Fan Restart and FanSense™ Technology for Fault Detection
TC642B/TC647B
DS21756C-page 2
2002-2013 Microchip Technology Inc.
Functional Block Diagram
TC642B/TC647B
Note: The V
OTF
comparator
Note
is for the TC642B device only.
70 mV
(typ)
V
OTF
10 k
V
SHDN
V
IN
C
F
V
MIN
GND
V
DD
V
OUT
FAULT
SENSE
Clock
Generator
Control
Logic
3xT
PWM
Timer
Start-up
Timer
Missing
Pulse
Detect
2002-2013 Microchip Technology Inc.
DS21756C-page 3
TC642B/TC647B
1.0
ELECTRICAL
CHARACTERISTICS
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.
PIN FUNCTION TABLE
Name
Function
V
IN
Analog Input
C
F
Analog Output
V
MIN
Analog Input
GND
Ground
SENSE
Analog Input
FAULT
Digital (Open-Drain) Output
V
OUT
Digital Output
V
DD
Power Supply Input
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
Sym
Min
Typ
Max
Units
Conditions
Supply Voltage
V
DD
3.0
—
5.5
V
Supply Current, Operating
I
DD
—
200
400
µA
Pins 6, 7 Open,
C
F
= 1 µF, V
IN
= V
C(MAX)
Supply Current, Shutdown Mode
I
DD(SHDN)
—
30
—
µA
Pins 6, 7 Open,
C
F
= 1 µF, V
MIN
= 0.35V
V
OUT
Output
Sink Current at V
OUT
Output
I
OL
1.0
—
—
mA
V
OL
= 10% of V
DD
Source Current at V
OUT
Output
I
OH
5.0
—
—
mA
V
OH
= 80% of V
DD
V
IN
, V
MIN
Inputs
Input Voltage at V
IN
or V
MIN
for 100%
PWM Duty Cycle
V
C(MAX)
2.45
2.60
2.75
V
Over-Temperature Indication
Threshold
V
OTF
V
C(MAX)
+
20 mV
V
For TC642B Only
Over-Temperature Indication
Threshold Hysteresis
V
OTF-HYS
80
mV
For TC642B Only
V
C(MAX)
- V
C(MIN)
V
C(SPAN)
1.3
1.4
1.5
V
Minimum Speed Threshold
V
MIN
V
C(MAX)
-
V
C(SPAN)
V
C(MAX)
V
Voltage Applied to V
MIN
to Ensure
Shutdown Mode
V
SHDN
—
—
V
DD
x 0.13
V
Voltage Applied to V
MIN
to Release
Shutdown Mode
V
REL
V
DD
x 0.19
—
—
V
V
DD
= 5V
Hysteresis on V
SHDN
, V
REL
V
HYST
—
0.03 x V
DD
—
V
V
IN
, V
MIN
Input Leakage
I
IN
- 1.0
—
+1.0
µA
Note 1
Pulse-Width Modulator
PWM Frequency
f
PWM
26
30
34
Hz
C
F
= 1.0 µF
Note
1:
Ensured by design, tested during characterization.
2:
For V
DD
< 3.7V, t
STARTUP
and t
MP
timers are typically 13/f.
TC642B/TC647B
DS21756C-page 4
2002-2013 Microchip Technology Inc.
TEMPERATURE SPECIFICATIONS
SENSE Input
SENSE Input Threshold Voltage with
Respect to GND
V
TH(SENSE)
50
70
90
mV
Blanking time to ignore pulse due to
V
OUT
turn-on
t
BLANK
—
3.0
—
µsec
FAULT Output
Output Low Voltage
V
OL
—
—
0.3
V
I
OL
= 2.5 mA
Missing Pulse Detector Timer
t
MP
—
32/f
—
sec
Note 2
Start-Up Timer
t
STARTUP
—
32/f
—
sec
Note 2
Diagnostic Timer
t
DIAG
—
3/f
—
sec
Electrical Characteristics: Unless otherwise noted, all parameters apply at V
DD
= 3.0V to 5.5V
Parameters
Symbol
Min
Typ
Max
Units
Conditions
Temperature Ranges:
Specified Temperature Range
T
A
-40
—
+85
°C
Operating Temperature Range
T
A
-40
—
+125
°C
Storage Temperature Range
T
A
-65
—
+150
°C
Thermal Package Resistances:
Thermal Package Resistance, 8-Pin MSOP
JA
—
200
—
°C/W
Thermal Package Resistance, 8-Pin SOIC
JA
—
155
—
°C/W
Thermal Package Resistance, 8-Pin PDIP
JA
—
125
—
°C/W
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
Sym
Min
Typ
Max
Units
Conditions
Note
1:
Ensured by design, tested during characterization.
2:
For V
DD
< 3.7V, t
STARTUP
and t
MP
timers are typically 13/f.
2002-2013 Microchip Technology Inc.
DS21756C-page 5
TC642B/TC647B
TIMING SPECIFICATIONS
FIGURE 1-1:
TC642B/TC647B Start-Up Timing.
FIGURE 1-2:
Fan Fault Occurrence.
FIGURE 1-3:
Recovery From Fan Fault.
V
OUT
FAULT
SENSE
t
STARTUP
V
OUT
FAULT
SENSE
33.3 msec (C
F
= 1 µF)
t
MP
t
MP
t
DIAG
V
OUT
FAULT
SENSE
Minimum 16 pulses
t
MP
TC642B/TC647B
DS21756C-page 6
2002-2013 Microchip Technology Inc.
FIGURE 1-4:
TC642B/TC647B Electrical Characteristics Test Circuit.
1
2
3
4
6
5
7
8
V
IN
C
F
V
MIN
GND
FAULT
SENSE
V
OUT
V
DD
R
3
R
1
C
3
0.1 µF
C
2
1 µF
V
DD
C
1
0.1 µF
+
-
V
IN
+
-
C
4
0.1 µF
V
MIN
+
-
R
2
K
1
K
2
0.1 µF
1 µF
.01 µF
C
7
C
6
C
5
R
4
V
SENSE
(pulse voltage source)
K
4
K
3
+
-
Current
limited
voltage
source
V
DD
R
5
Current
limited
voltage
source
C
8
0.1 µF
R
6
Note: C
5
and C
7
are adjusted to get the necessary 1 µF value.
TC642B
TC647B
+
-
2002-2013 Microchip Technology Inc.
DS21756C-page 7
TC642B/TC647B
2.0
TYPICAL PERFORMANCE CURVES
Note: Unless otherwise indicated, V
DD
= 5V, T
A
= +25°C.
FIGURE 2-1:
I
DD
vs. Temperature.
FIGURE 2-2:
PWM Sink Current (I
OL
) vs.
V
OL
.
FIGURE 2-3:
PWM Source Current (I
OH
)
vs. V
DD
-V
OH
.
FIGURE 2-4:
PWM Frequency vs.
Temperature.
FIGURE 2-5:
I
DD
vs. V
DD
.
FIGURE 2-6:
I
DD
Shutdown vs.
Temperature.
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.
125
130
135
140
145
150
155
160
165
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
I
DD
(µA
)
V
DD
= 3.0V
V
DD
= 5.5V
Pins 6 & 7 Open
C
F
= 1 µF
0
2
4
6
8
10
12
14
16
0
50
100 150 200 250 300 350 400 450 500 550 600
V
OL
(mV)
I
OL
(m
A
)
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 3.0V
V
DD
= 4.0V
0
2
4
6
8
10
12
14
16
0
100
200
300
400
500
600
700
800
V
DD
- V
OH
(mV)
I
OH
(m
A
)
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 3.0V
V
DD
= 4.0V
28.50
29.00
29.50
30.00
30.50
-40 -25 -10
5
20
35
50
65
80
95 110 125
Temperature (ºC)
Oscillator Frequency (Hz)
V
DD
= 3.0V
V
DD
= 5.5V
C
F
= 1.0PF
125
130
135
140
145
150
155
160
165
170
3
3.5
4
4.5
5
5.5
V
DD
(V)
I
DD
(µA
)
T
A
= -40ºC
T
A
= -5ºC
T
A
= +125ºC
T
A
= +90ºC
Pins 6 & 7 Open
C
F
= 1 µF
15
18
21
24
27
30
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
I
DD
S
hutdow
n (µA
)
V
DD
= 5.5V
V
DD
= 3.0V
Pins 6 & 7 Open
V
MIN
= 0V
TC642B/TC647B
DS21756C-page 8
2002-2013 Microchip Technology Inc.
Note: Unless otherwise indicated, V
DD
= 5V, T
A
= +25°C.
FIGURE 2-7:
FAULT V
OL
vs.
Temperature.
FIGURE 2-8:
V
C(MAX)
vs. Temperature.
FIGURE 2-9:
V
C(MIN)
vs. Temperature.
FIGURE 2-10:
Sense Threshold
(V
TH(SENSE)
) vs. Temperature.
FIGURE 2-11:
FAULT I
OL
vs. V
OL
.
FIGURE 2-12:
PWM Source Current (I
OH
)
vs. Temperature.
10
20
30
40
50
60
70
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
FA
U
LT V
OL
(mV)
I
OL
= 2.5 mA
V
DD
= 3.0V
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 4.0V
2.570
2.580
2.590
2.600
2.610
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
C(M
A
X)
(V
)
V
DD
= 5.0V
V
DD
= 5.5V
V
DD
= 3.0V
C
F
= 1 µF
1.180
1.190
1.200
1.210
1.220
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
C(M
IN)
(V
)
V
DD
= 5.0V
V
DD
= 3.0V
C
F
= 1 µF
69.5
70.0
70.5
71.0
71.5
72.0
72.5
73.0
73.5
74.0
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
TH(SENSE)
(m
V
)
V
DD
= 3.0V
V
DD
= 4.0V
V
DD
= 5.5V
V
DD
= 5.0V
0
2
4
6
8
10
12
14
16
18
20
22
0
50
100
150
200
250
300
350
400
V
OL
(mV)
FA
U
LT I
OL
(m
A
)
V
DD
= 5.5V
V
DD
= 3.0V
V
DD
= 4.0V
V
DD
= 5.0V
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
OUT
I
OH
(m
A
)
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 4.0V
V
DD
= 3.0V
V
OH
= 0.8V
DD
2002-2013 Microchip Technology Inc.
DS21756C-page 9
TC642B/TC647B
Note: Unless otherwise indicated, V
DD
= 5V, T
A
= +25°C.
FIGURE 2-13:
PWM Sink Current (I
OL
) vs.
Temperature.
FIGURE 2-14:
V
SHDN
Threshold vs.
Temperature.
FIGURE 2-15:
V
REL
Threshold vs.
Temperature.
FIGURE 2-16:
V
OTF
Threshold vs.
Temperature.
FIGURE 2-17:
Over-Temperature
Hysteresis (V
OTF-HYS
) vs. Temperature.
0
5
10
15
20
25
30
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
OUT
I
OL
(m
A
)
V
DD
= 5.5V
V
DD
= 5.0V
V
DD
= 4.0V
V
DD
= 3.0V
V
OL
= 0.1V
DD
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
SHDN
(V
)
V
DD
= 3.0V
V
DD
= 4.0V
V
DD
= 5.0V
V
DD
= 5.5V
0.40
0.45
0.50
0.55
0.60
0.65
0.70
0.75
0.80
0.85
0.90
0.95
1.00
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
REL
(V
)
V
DD
= 3.0V
V
DD
= 4.0V
V
DD
= 5.0V
V
DD
= 5.5V
2.595
2.600
2.605
2.610
2.615
2.620
2.625
2.630
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
OT
F
(V
)
V
DD
= 3.0V
V
DD
= 5.0V
V
DD
= 5.5V
70
75
80
85
90
95
100
-40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
V
OT
F
H
yster
esis (m
V
)
V
DD
= 5.5V
V
DD
= 3.0V
TC642B/TC647B
DS21756C-page 10
2002-2013 Microchip Technology Inc.
3.0
PIN FUNCTIONS
The description of the pins are given in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
3.1
Analog Input (V
IN
)
The thermistor network (or other temperature sensor)
connects to V
IN
. A voltage range of 1.20V to 2.60V (typ-
ical) on this pin drives an active duty cycle of 0% to
100% on the V
OUT
pin.
3.2
Analog Output (C
F
)
C
F
is the positive terminal for the PWM ramp generator
timing capacitor. The recommended value for the C
F
capacitor is 1.0 µF for 30 Hz PWM operation.
3.3
Analog Input (V
MIN
)
An external resistor divider connected to V
MIN
sets the
minimum fan speed by fixing the minimum PWM duty
cycle (1.20V to 2.60V = 0% to 100%, typical). The
TC642B and TC647B devices enter shutdown mode
when 0
V
MIN
V
SHDN
. During shutdown, the FAULT
output is inactive and supply current falls to 30 µA
(typical).
3.4
Analog Input (SENSE)
Pulses are detected at SENSE as fan rotation chops
the current through a sense resistor. The absence of
pulses indicates a fan fault condition.
3.5
Digital (Open-Drain) Output
(FAULT)
The FAULT line goes low to indicate a fault condition.
When FAULT goes low due to a fan fault, the output will
remain low until the fan fault condition has been
removed (16 pulses have been detected at the SENSE
pin in a 32/f period). For the TC642B device, the FAULT
output will also be asserted when the V
IN
voltage
reaches the V
OTF
treshold of 2.62V (typical). This gives
an over-temperature/100% fan speed indication
.
3.6
Digital Output (V
OUT
)
V
OUT
is an active-high complimentary output and
drives the base of an external NPN transistor (via an
appropriate base resistor) or the gate of an N-channel
MOSFET. This output has asymmetrical drive. During a
fan fault condition, the V
OUT
output is continuously on.
3.7
Power Supply Input (V
DD
)
The V
DD
pin with respect to GND provides power to the
device. This bias supply voltage may be independent of
the fan power supply.
Pin
Name
Function
1
V
IN
Analog Input
2
C
F
Analog Output
3
V
MIN
Analog Input
4
GND
Ground
5
SENSE
Analog Input
6
FAULT
Digital (Open-Drain) Output
7
V
OUT
Digital Output
8
V
DD
Power Supply Input