MICROCHIP TC646BEOA713

M TC646B/TC648B/TC649B
PWM Fan Speed Controllers With Auto-Shutdown, Fan
Restart and FanSense™ Technology for Fault Detection
Features
Description
• 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 TC646B/
TC648B/TC649B Supply Voltage
- Supports any Fan Voltage
• FanSense™ Fault Detection Circuit Protects
Against Fan Failure and Aids System Testing
(TC646B/TC649B)
• Automatic Shutdown Mode for “Green” Systems
• Supports Low Cost NTC/PTC Thermistors
• Over-Temperature Indication (TC646B/TC648B)
• Fan Auto-Restart
• Space-Saving 8-Pin MSOP Package
The TC646B/TC648B/TC649B devices are new versions of the existing TC646/TC648/TC649 fan speed
controllers. These devices are switch-mode fan speed
controllers that incorporate a new fan auto-restart function. Temperature-proportional speed control is accomplished using pulse width modulation. A thermistor (or
other voltage output temperature sensor) connected to
the VIN input supplies the required control voltage of
1.20V to 2.60V (typical) for 0% to 100% PWM duty
cycle. The auto-shutdown threshold/temperature is set
by a simple resistor divider on the VAS input. An integrated Start-Up Timer ensures reliable fan motor startup at turn-on, coming out of shutdown mode, autoshutdown mode or following a transient fault. A logic
low applied to VIN (pin 1) causes fan shutdown.
Applications
•
•
•
•
•
•
Personal Computers & Servers
LCD Projectors
Datacom & Telecom Equipment
Fan Trays
File Servers
General-Purpose Fan Speed Control
Package Types
MSOP, PDIP, SOIC
VIN 1
CF 2
VAS 3
TC646B
TC649B
GND 4
VIN 1
CF 2
VAS 3
TC648B
GND 4
 2003 Microchip Technology Inc.
8
VDD
7
VOUT
6
FAULT
5
SENSE
8
VDD
7
VOUT
6
OTF
5
NC
The TC646B and TC649B 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 missingpulse detector monitors this pin during fan operation. A
stalled, open or unconnected fan causes the TC646B/
TC649B device to turn the VOUT output on full (100%
duty cycle). If the fan 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 VOUT
output is on full during the fan fault condition in order to
attempt to restart the fan. FAULT (TC646B) or OTF
(TC648B) is also asserted if the PWM reaches 100%
duty cycle, indicating that maximum cooling capability
has been reached and a possible overheating condition
exists.
The TC646B, TC648B and TC649B devices are available in 8-pin plastic MSOP, SOIC and PDIP packages.
The specified temperature range of these devices is
-40 to +85ºC.
DS21755B-page 1
TC646B/TC648B/TC649B
Functional Block Diagram
TC646B/TC649B
VOTF
VIN
VDD
Note
Note: The V OTF comparator
is for the TC646B device only.
Control
Logic
CF
Clock
Generator
3xT PWM
Timer
VOUT
Start-up
Timer
VAS
VSHDN
Missing
Pulse
Detect
FAULT
SENSE
10 kΩ
GND
70 mV
(typ)
TC648B
VOTF
VIN
VDD
Control
Logic
CF
Clock
Generator
VOUT
Start-up
Timer
VAS
VSHDN
OTF
NC
GND
DS21755B-page 2
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
1.0
ELECTRICAL
CHARACTERISTICS
PIN FUNCTION TABLE
Name
Absolute Maximum Ratings†
Function
VIN
Analog Input
Supply Voltage (VDD ) .......................................................6.0V
CF
Analog Output
Input Voltage, Any Pin................(GND - 0.3V) to (VDD +0.3V)
VAS
Analog Input
GND
Ground
Operating Temperature Range ....................- 40°C to +125°C
Maximum Junction Temperature, TJ ........................... +150°C
SENSE/NC
Analog Input.
No Connect (NC) for TC648B
FAULT/OTF
Digital (Open-Drain) Output
OTF for TC648B
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. Exposure to maximum rating conditions for extended periods may
affect device reliability.
VOUT
Digital Output
VDD
Power Supply Input
ELECTRICAL CHARACTERISTICS
Electrical Specifications: Unless otherwise specified, all limits are specified for -40°C < TA < +85°C, VDD = 3.0V to 5.5V.
Parameters
Sym
Min
Typ
Max
Units
Supply Voltage
VDD
3.0
—
5.5
V
Supply Current, Operating
IDD
—
200
400
µA
Pins 6, 7 Open,
CF = 1 µF, VIN = VC(MAX)
IDD(SHDN)
—
30
—
µA
Pins 6, 7 Open,
CF = 1 µF, VIN = 0.35V
Sink Current at VOUT Output
IOL
1.0
—
—
mA
VOL = 10% of VDD
Source Current at VOUT Output
IOH
5.0
—
—
mA
VOH = 80% of VDD
VC(MAX)
2.45
2.60
2.75
V
Supply Current, Shutdown Mode
Conditions
VOUT Output
VIN , VAS Inputs
Input Voltage at VIN for 100% PWM
Duty Cycle
Over-Temperature Indication
Threshold
VOTF
VC(MAX) +
20 mV
V
For TC646B and TC648B
Over-Temperature Indication
Threshold Hysteresis
VOTF-HYS
80
mV
For TC646B and TC648B
VC(MAX) - VC(MIN)
VC(SPAN)
1.3
1.4
1.5
V
VHAS
—
70
—
mV
VAS
VC(MAX) VC(SPAN)
—
VC(MAX)
V
Voltage Applied to VIN to Ensure
Shutdown Mode
VSHDN
—
—
VDD x 0.13
V
Voltage Applied to VIN to Release
Shutdown Mode
VREL
VDD x 0.19
—
—
V
Hysteresis on VSHDN , VREL
VHYST
—
0.03 X
VDD
—
V
IIN
- 1.0
—
+1.0
µA
Hysteresis on Auto-Shutdown
Comparator
Auto-Shutdown Threshold
VIN , VAS Input Leakage
Note 1:
2:
VDD = 5V
Note 1
Ensured by design, tested during characterization.
For VDD < 3.7V, tSTARTUP and tMP timers are typically 13/f.
 2003 Microchip Technology Inc.
DS21755B-page 3
TC646B/TC648B/TC649B
ELECTRICAL CHARACTERISTICS (CONTINUED)
Electrical Specifications: Unless otherwise specified, all limits are specified for -40°C < TA < +85°C, VDD = 3.0V to 5.5V.
Parameters
Sym
Min
Typ
Max
Units
fPWM
26
30
34
Hz
SENSE Input Threshold Voltage
with Respect to GND
VTH(SENSE)
50
70
90
mV
Blanking time to ignore pulse due
to VOUT turn-on
tBLANK
—
3.0
—
µsec
V OL
—
—
0.3
V
Conditions
Pulse-Width Modulator
PWM Frequency
CF = 1.0 µF
SENSE Input (TC646B & TC649B)
FAULT / OTF Output
Output Low Voltage
Missing Pulse Detector Timer
Start-up Timer
Diagnostic Timer
Note 1:
2:
IOL = 2.5 mA
tMP
—
32/f
—
sec
TC646B and TC649B, Note 2
tSTARTUP
—
32/f
—
sec
Note 2
tDIAG
—
3/f
—
sec
TC646B and TC649B
Ensured by design, tested during characterization.
For VDD < 3.7V, tSTARTUP and tMP timers are typically 13/f.
TEMPERATURE SPECIFICATIONS
Electrical Characteristics: Unless otherwise noted, all parameters apply at V DD = 3.0V to 5.5V
Parameters
Sym
Min
Typ
Max
Units
Specified Temperature Range
TA
-40
—
+85
°C
Operating Temperature Range
TA
-40
—
+125
°C
Storage Temperature Range
TA
-65
—
+150
°C
Thermal Package Resistance, 8-Pin MSOP
θJA
—
200
—
°C/W
Thermal Package Resistance, 8-Pin SOIC
θJA
—
155
—
°C/W
Thermal Package Resistance, 8-Pin PDIP
θJA
—
125
—
°C/W
Conditions
Temperature Ranges
Thermal Package Resistances
DS21755B-page 4
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
TIMING SPECIFICATIONS
tSTARTUP
VOUT
FAULT / OTF
(TC646B and TC649B)
SENSE
FIGURE 1-1:
TC646B/TC648B/TC649B Start-up Timing.
33.3 msec (CF = 1 µF)
tDIAG
tMP
tMP
VOUT
FAULT
SENSE
FIGURE 1-2:
Fan Fault Occurrence (TC646B and TC649B).
tMP
VOUT
FAULT
Minimum 16 pulses
SENSE
FIGURE 1-3:
Recovery From Fan Fault (TC646B and TC649B).
 2003 Microchip Technology Inc.
DS21755B-page 5
TC646B/TC648B/TC649B
C2
1 µF
C1
0.1 µF
+
-
VDD
8
R1
+
-
VIN
1
C3
0.1 µF
R2
+
-
VAS
3
C4
0.1 µF
VIN
VDD
VOUT
K3
7
R6
+
-
TC646B
TC648B
TC649B
VDD
VAS
FAULT / OTF
R5
K4
6
+
2
CF
GND
K1
C7
.01 µF
K2
C6
1 µF
4
C5
0.1 µF
C8
0.1 µF
Current
limited
voltage
source
SENSE
R4
5
R3
Current
limited
voltage
source
VSENSE
(pulse voltage source)
TC646B and TC649B
Note: C5 and C7 are adjusted to get the necessary 1 µF value.
FIGURE 1-4:
DS21755B-page 6
TC646B/TC648B/TC649B Electrical Characteristics Test Circuit.
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
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 = 5V, TA = 25°C.
30.50
Pins 6 & 7 Open
CF = 1 µF
160
Oscillator Frequency (Hz)
165
VDD = 5.5V
IDD (µA)
155
150
145
VDD = 3.0V
140
135
130
CF = 1.0PF
VDD = 3.0V
30.00
VDD = 5.5V
29.50
29.00
28.50
125
-40
-25
-10
5
20
35
50
65
80
95
-40 -25 -10
110 125
5
IDD vs. Temperature.
FIGURE 2-4:
Temperature.
16
50
80
95
110 125
PWM Frequency vs.
Pins 6 & 7 Open
CF = 1 µF
165
VDD = 5.0V
TA = +125ºC
TA = +90ºC
160
12
155
VDD = 5.5V
VDD = 4.0V
IDD (µA)
10
8
VDD = 3.0V
6
150
TA = -5ºC
145
140
4
TA = -40ºC
135
2
130
0
125
0
50 100 150 200 250 300 350 400 450 500 550 600
3
3.5
4
VOL (mV)
FIGURE 2-2:
VOL.
4.5
5
5.5
VDD (V)
PWM Sink Current (IOL) vs.
IDD vs. VDD.
FIGURE 2-5:
30
16
14
IDD Shutdown (µA)
VDD = 5.0V
12
IOH (mA)
65
170
14
IOL (mA)
35
Temperature (ºC)
Temperature (ºC)
FIGURE 2-1:
20
VDD = 4.0V
10
V DD = 5.5V
8
VDD = 3.0V
6
4
2
0
V DD = 5.5V
27
24
VDD = 3.0V
21
18
Pins 6 & 7 Open
VIN = 0V
15
0
100
200
300
400
500
600
700
800
-40
-25
VDD - VOH (mV)
FIGURE 2-3:
vs. VDD - VOH.
PWM Source Current (IOH)
 2003 Microchip Technology Inc.
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
FIGURE 2-6:
Temperature.
IDD Shutdown vs.
DS21755B-page 7
TC646B/TC648B/TC649B
Note: Unless otherwise indicated, VDD = 5V, TA = 25°C.
74.0
IOL = 2.5 mA
73.5
60
VDD = 3.0V
50
VDD = 4.0V
40
30
VDD = 5.0V
VDD = 5.5V
20
VDD = 3.0V
73.0
VTH(SENSE) (mV)
FAULT / OTF VOL (mV)
70
VDD = 4.0V
72.5
72.0
71.5
VDD = 5.5V
71.0
VDD = 5.0V
70.5
70.0
10
69.5
-40
-25
-10
5
20
35
50
65
80
95
-40 -25 -10
110 125
5
Temperature (ºC)
FAULT / OTF VOL vs.
FIGURE 2-7:
Temperature.
50
65
80
95
110 125
22
VDD = 5.0V
2.590
VDD = 3.0V
2.580
FAULT / OTF IOL (mA)
VDD = 5.5V
2.600
VC(MAX) (V)
35
FIGURE 2-10:
Sense Threshold
(VTH(SENSE)) vs. Temperature.
2.610
CF = 1 µF
20
18
16
VDD = 5.0V
14
12
10
VDD = 5.5V
VDD = 4.0V
8
VDD = 3.0V
6
4
2
0
2.570
-40 -25 -10
5
20
35
50
65
80
95
0
110 125
50
100
150
VC(MAX) vs. Temperature.
FIGURE 2-8:
1.220
250
300
350
400
FAULT / OTF IOL vs. VOL.
FIGURE 2-11:
45.00
CF = 1 µF
VOH = 0.8VDD
40.00
VOUT IOH (mA)
1.210
1.200
VDD = 5.0V
VDD = 3.0V
1.190
200
VOL (mV)
Temperature (ºC)
VC(MIN) (V)
20
Temperature (ºC)
35.00
VDD = 5.0V
30.00
25.00
VDD = 4.0V
20.00
15.00
10.00
1.180
VDD = 5.5V
VDD = 3.0V
5.00
-40 -25 -10
5
20
35
50
65
80
95
110 125
-40 -25 -10
Temperature (ºC)
FIGURE 2-9:
DS21755B-page 8
VC(MIN) vs. Temperature.
5
20
35
50
65
80
95
110 125
Temperature (ºC)
FIGURE 2-12:
vs. Temperature.
PWM Source Current (IOH)
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
Note: Unless otherwise indicated, VDD = 5V, TA = 25°C.
30
25
VDD = 5.5V
2.625
VDD = 5.5V
VDD = 4.0V
15
VDD = 5.0V
2.620
VDD = 5.0V
20
VOTF (V)
VOUT IOL (mA)
2.630
VOL = 0.1VDD
10
2.615
VDD = 3.0V
2.610
2.605
VDD = 3.0V
5
2.600
0
2.595
-40
-25
-10
5
20
35
50
65
80
95
110 125
-40 -25 -10
5
Temperature (ºC)
PWM Sink Current (IOL) vs.
FIGURE 2-13:
Temperature.
FIGURE 2-16:
Temperature.
0.75
VDD = 5.5V
VOTF Hysteresis (mV)
VSHDN (V)
0.65
35
50
65
80
95
110 125
VOTF Threshold vs.
100
0.80
0.70
20
Temperature (ºC)
VDD = 5.0V
0.60
0.55
VDD = 4.0V
0.50
0.45
VDD = 3.0V
0.40
95
90
VDD = 5.5V
85
VDD = 3.0V
80
75
0.35
0.30
70
-40 -25 -10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
VREL (V)
1.00
0.95
0.90
0.85
0.80
0.75
0.70
0.65
0.60
0.55
0.50
0.45
0.40
-25
-10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
VSHDN Threshold vs.
FIGURE 2-14:
Temperature.
-40
FIGURE 2-17:
Over-Temperature
Hysteresis (VOTF-HYS) vs. Temperature.
VDD = 5.5V
VDD = 5.0V
V DD = 4.0V
V DD = 3.0V
-40 -25 -10
5
20
35
50
65
80
95
110 125
Temperature (ºC)
FIGURE 2-15:
Temperature.
VREL Threshold vs.
 2003 Microchip Technology Inc.
DS21755B-page 9
TC646B/TC648B/TC649B
3.0
PIN FUNCTIONS
The descriptions of the pins are given in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLE
Pin
Name
1
VIN
Analog Input
2
CF
Analog Output
3
VAS
Analog Input
4
GND
Ground
5
SENSE/NC
Analog Input/No Connect. NC for TC648B.
6
FAULT/OTF
Digital (Open-Drain) Output
OTF for TC648B
7
VOUT
Digital Output
8
VDD
Power Supply Input
3.1
Function
Analog Input (VIN)
The thermistor network (or other temperature sensor)
connects to VIN. A voltage range of 1.20V to 2.60V (typical) on this pin drives an active duty cycle of 0% to
100% on the VOUT pin. The TC646B, TC648B and
TC649B devices enter shutdown mode when
0 ≤ VIN ≤ VSHDN. During shutdown, the FAULT/OTF
output is inactive and supply current falls to 30 µA
(typical).
3.2
Analog Output (CF)
CF is the positive terminal for the PWM ramp generator
timing capacitor. The recommended value for the CF
capacitor is 1.0 µF for 30 Hz PWM operation.
3.3
Analog Input (VAS)
An external resistor divider connected to VAS sets the
auto-shutdown threshold. Auto-shutdown occurs when
VIN < VAS. The fan is automatically restarted when
VIN > (VAS + VHAS). During auto-shutdown, the
FAULT/OTF 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/OTF)
FAULT/OTF goes low to indicate a fault condition.
When FAULT goes low due to a fan fault (TC646B and
TC649B devices), 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 TC646B and TC648B devices, the FAULT/OTF output will also be asserted when the VIN voltage reaches
the VOTF threshold of 2.62V (typical). This gives an
over-temperature/100% fan speed indication.
3.6
Digital Output (VOUT)
VOUT is an active-high complimentary output that
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 VOUT output is continuously on.
3.7
Power Supply Input (VDD)
The VDD pin with respect to GND provides power to the
device. This bias supply voltage may be independent of
the fan power supply.
3.8
Ground (GND)
Ground terminal.
3.9
No Connect (NC)
No internal connection.
DS21755B-page 10
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
4.0
DEVICE OPERATION
The TC646B/TC648B/TC649B devices are a family of
temperature-proportional, PWM mode, fan speed controllers. Features of the family include minimum fan
speed, fan auto-shutdown, fan auto-restart, remote
shutdown, over-temperature indication and fan fault
detection.
The TC64XB family is slightly different from the original
TC64X family, which includes the TC642, TC646,
TC647, TC648 and TC649 devices. Changes have
been made to adjust the operation of the device during
a fan fault condition.
The key change to the TC64XB family of devices
(TC642B, TC647B, TC646B, TC648B, TC649B) is that
the FAULT and VOUT outputs no longer “latch” to a
state during a fan fault condition. The TC646B/
TC648B/TC649B family will continue to monitor the
operation of the fan so that when the fan returns to normal operation, the fan speed controller will also return
to normal operation (PWM mode). The operation and
features of these devices are discussed in the following
sections.
4.1
The PWM approach to fan speed control results in
much less power dissipation in the drive element. This
allows smaller devices to be used and will not require
special heatsinking to remove the power being
dissipated in the package.
The other advantage of the PWM approach is that the
voltage being applied to the fan is always near 12V.
This eliminates any concern about not supplying a high
enough voltage to run the internal fan components,
which is very relevant in linear fan speed control.
4.2
PWM Fan Speed Control
The TC646B, TC648B and TC649B devices implement
PWM fan speed control by varying the duty cycle of a
fixed-frequency pulse train. The duty cycle of a waveform is the on time divided by the total period of the
pulse. For example, if we take a 100 Hz waveform
(10 ms) with an on time of 5.0 ms, the duty cycle of this
waveform is 50% (5.0 ms / 10.0 ms). This example is
shown in Figure 4-1.
t
Fan Speed Control Methods
The speed of a DC brushless fan is proportional to the
voltage across it. This relationship will vary from fan-tofan and should be characterized on an individual basis.
The speed versus applied voltage relationship can then
be used to set up the fan speed control algorithm.
There are two main methods for fan speed control. The
first is pulse width modulation (PWM) and the second
is linear. Using either method, the total system power
requirement to run the fan is equal. The difference
between the two methods is where the power is
consumed.
The following example compares the two methods for
a 12V, 120 mA fan running at 50% speed. With 6V
applied across the fan, the fan draws an average
current of 68 mA.
Using a linear control method, there is 6V across the
fan and 6V across the drive element. With 6V and
68 mA, the drive element is dissipating 410 mW of
power.
Using the PWM approach, the fan voltage is modulated
at a 50% duty cycle, with most of the 12V being
dropped across the fan. With 50% duty cycle, the fan
draws a RMS current of 110 mA and an average current of 72 mA. Using a MOSFET with a 1Ω RDS(on) (a
fairly typical value for this low current), the power dissipation in the drive element would be: 12 mW (Irms2 *
RDS(on)). Using a standard 2N2222A NPN transistor
(assuming a Vce-sat of 0.8V), the power dissipation
would be 58 mW (Iavg* Vce-sat).
 2003 Microchip Technology Inc.
ton
toff
D = Duty Cycle
D = ton / t
FIGURE 4-1:
Waveform.
t = Period
t = 1/f
f = Frequency
Duty Cycle of a PWM
The TC646B/TC648B/TC649B devices generate a
pulse train with a typical frequency of 30 Hz
(CF = 1 µF). The duty cycle can be varied from 0% to
100%. The pulse train generated by the TC646B/
TC648B/TC649B device drives the gate of an external
N-channel MOSFET or the base of an NPN transistor.
(shown in Figure 4-2). See Section 5.5, “Output Drive
Device Selection”, for more information on output drive
device selection.
DS21755B-page 11
TC646B/TC648B/TC649B
FAN
VDD
D
TC646B VOUT
TC648B
TC649B
G
QDRIVE
S
GND
FIGURE 4-2:
PWM Fan Drive.
By modulating the voltage applied to the gate of the
MOSFET (QDRIVE), the voltage that is applied to the
fan is also modulated. When the VOUT pulse is high, the
gate of the MOSFET is turned on, pulling the voltage at
the drain of QDRIVE to zero volts. This places the full
12V across the fan for the ton period of the pulse. When
the duty cycle of the drive pulse is 100% (full on,
ton = t), the fan will run at full speed. As the duty cycle
is decreased (pulse on time “ton” is lowered), the fan
will slow down proportionally. With the TC646B,
TC648B and TC649B devices, the duty cycle is controlled by the VIN input and can also be terminated by
the VAS input (auto-shutdown). This is described in
more detail in Section 5.5, “Output Drive Device
Selection”.
4.3
Fan Start-up
Often overlooked in fan speed control is the actual
start-up control period. When starting a fan from a nonoperating condition (fan speed is zero revolutions per
minute (RPM)), the desired PWM duty cycle or average
fan voltage cannot be applied immediately. Since the
fan is at a rest position, the fan’s inertia must be overcome to get it started. The best way to accomplish this
is to apply the full rated voltage to the fan for a minimum
of one second. This will ensure that in all operating
environments, the fan will start and operate properly.
An example of the start-up timing is shown in
Figure 1-1.
A key feature of the TC646B/TC648B/TC649B devices
is the start-up timer. When power is first applied to the
device, or when the device is brought out of the shutdown/auto-shutdown modes of operation, the VOUT
output will go to a high state for 32 PWM cycles (one
second for CF = 1 µF). This will drive the fan to full
speed for this time frame.
During the start-up period for the TC646B and TC649B
devices, the SENSE pin is being monitored for fan
pulses. If pulses are detected during this period, the fan
speed controller will then move to PWM operation. If
pulses are not detected during the start-up period, the
DS21755B-page 12
start-up timer is activated again. If pulses are not
detected at the SENSE pin during this additional
period, the FAULT output will go low to indicate that a
fan fault condition has occurred. See Section 4.7,
“FAULT/OTF Output”, for more details.
4.4
PWM Frequency & Duty Cycle
Control (CF & VIN Pins)
The frequency of the PWM pulse train is controlled by
the C F pin. By attaching a capacitor to the C F pin, the
frequency of the PWM pulse train can be set to the
desired value. The typical PWM frequency for a 1.0 µF
capacitor is 30 Hz. The frequency can be adjusted by
raising or lowering the value of the capacitor. The CF
pin functions as a ramp generator. The voltage at this
pin will ramp from 1.20V to 2.60V (typically) as a sawtooth waveform. An example of this is shown in
Figure 4-3.
2.8
CF = 1 µF
2.6
VCMAX
2.4
CF Voltage (V)
12V
2.2
2.0
1.8
1.6
1.4
1.2
VCMIN
1.0
0
20
40
60
80
100
Time (msec)
FIGURE 4-3:
CF Pin Voltage.
The duty cycle of the PWM output is controlled by the
voltage at the VIN input pin. The duty cycle of the PWM
output is produced by comparing the voltage at the VIN
pin to the voltage ramp at the CF pin. When the voltage
at the VIN pin is 1.20V, the duty cycle will be 0%. When
the voltage at the V IN pin is 2.60V, the PWM duty cycle
will be 100% (these are both typical values). The
VIN-to-PWM duty cycle relationship is shown in
Figure 4-4.
The lower value of 1.20V is referred to as “VCMIN” and
the 2.60V threshold is referred to as “VCMAX”. A calculation for duty cycle is shown in the equation below. The
voltage range between VCMIN and VCMAX is characterized as “VCSPAN“ and has a typical value of 1.4V, with
minimum and maximum values of 1.3V and 1.5V,
respectively.
EQUATION
PWM DUTY CYCLE
Duty Cycle (%) =
(VIN - VCMIN) * 100
VCMAX - VCMIN
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
For the TC646B, TC648B and TC649B devices, the V IN
pin is also used as the shutdown pin. The VSHDN and
VREL threshold voltages are characterized in the “Electrical Characteristics Table” of Section 1.0. If the VIN pin
voltage is pulled below the VSHDN threshold, the device
will shut down (VOUT output goes to a low state, the
FAULT/OTF pin is inactive). If the voltage on the VIN pin
then rises above the release threshold (VREL), the
device will go through a power-up sequence (assuming
that the V IN voltage is also higher than the voltage at
the VAS pin). The power-up sequence is shown later in
the “Behavioral Algorithm Flowcharts” of Section 4.9.
100
90
Duty Cycle (%)
80
70
60
50
40
30
20
10
When the device is in shutdown/auto-shutdown mode,
the VOUT output is actively held low. The output can be
varied from 0% (full off) to 100% duty cycle (full on). As
previously discussed, the duty cycle of the VOUT output
is controlled via the VIN input voltage and can be terminated based on the VAS voltage.
A base current-limiting resistor is required when using
a transistor as the external drive device in order to limit
the amount of drive current that is drawn from the VOUT
output.
The VOUT output can be directly connected to the gate
of an external MOSFET. One concern when doing this,
though, is that the fast turn-off time of the fan drive
MOSFET can cause a problem because the fan motor
looks like an inductor. When the MOSFET is turned off
quickly, the current in the fan wants to continue to flow
in the same direction. This causes the voltage at the
drain of the MOSFET to rise. If there aren’t any clamp
diodes internal to the fan, this voltage can rise above
the drain-to-source voltage rating of the MOSFET. For
this reason, an external clamp diode is suggested. This
is shown in Figure 4-5.
0
1
1.2
1.4
1.6
1.8
2
2.2
2.4
2.6
2.8
VIN (V)
FIGURE 4-4:
Cycle (Typical).
4.5
VIN Voltage vs. PWM Duty
Clamp Diode
FAN
Auto-Shutdown Mode (VAS)
For the TC646B, TC648B and TC649B devices, pin 3
is the VAS pin and is used for setting the auto-shutdown
threshold voltage.
Q1
VOUT
The auto-shutdown function provides a way to set a
threshold voltage (temperature) at which the fan will be
shut off. This way, if the temperature in the system
reaches a threshold at which the fan(s) no longer needs
to operate, the fan can be shutdown automatically.
The voltage range for the VAS pin is the same as the
voltage range for the VIN pin (1.20V to 2.60V). The voltage at the VAS pin is set in this range so that when the
voltage at the VIN pin decreases below the voltage at
the VAS pin (signifying that the threshold temperature
has been reached), the VOUT output is shut off (goes to
a low state). In auto-shutdown, the FAULT/OTF output
is inactive (high-impedance). Auto-shutdown mode is
exited when the VIN voltage exceeds the VAS voltage
by the auto-shutdown hysteresis voltage (VHAS). Upon
exiting auto-shutdown mode, the start-up timer is
triggered and the device returns to normal operation.
4.6
VOUT Output (PWM Output)
The VOUT output is a digital output designed for driving
the base of a transistor or the gate of a MOSFET. The
VOUT output is designed to be able to quickly raise the
base current or the gate voltage of the external drive
device to its final value.
 2003 Microchip Technology Inc.
RSENSE
GND
Q1: N-Channel MOSFET
FIGURE 4-5:
4.7
Clamp Diode for Fan.
FAULT/OTF Output
The FAULT/OTF output is an open-drain, active-low
output. For the TC646B and TC649B devices, pin 6 is
labeled as the FAULT output and indicates when a fan
fault condition has occurred. For the TC646B device,
the FAULT output also indicates when an over-temperature (OTF) condition has occurred. For the TC648B
device, pin 6 is the OTF output that indicates an overtemperature (OTF) condition has occurred.
DS21755B-page 13
TC646B/TC648B/TC649B
For the TC646B and TC648B devices, an over-temperature condition is indicated when the VIN input reaches
the V OTF threshold voltage (the VOTF threshold voltage
is typically 20 mV higher than the VCMAX threshold and
has 80 mV of hysteresis). This indicates that maximum
cooling capacity has been reached (the fan is at full
speed) and that an overheating situation can occur.
When the voltage at the VIN input falls below the VOTF
threshold voltage by the hysteresis value (VOTF-HYS),
the FAULT/OTF output will return to the high state (a
pull-up resistor is needed on the FAULT/OTF output).
For the TC646B/TC649B devices, a fan fault condition
is indicated when fan current pulses are no longer
detected at the SENSE pin. Pulses at the SENSE pin
indicate that the fan is spinning and conducting current.
4.8
Sensing Fan Operation (SENSE)
The SENSE input is an analog input used to monitor
the fan’s operation (the TC648B device does not incorporate the fan sensing feature). It does this by sensing
fan current pulses that represent fan rotation. When a
fan rotates, commutation of the fan current occurs as
the fan poles pass the armatures of the motor. The
commutation of the fan current makes the current
waveshape appear as pulses. There are two typical
current waveforms of brushless DC fan motors,
illustrated in Figures 4-6 and 4-7.
If pulses are not detected at the SENSE pin for
32 PWM cycles, the 3-cycle diagnostic timer is fired.
This means that the VOUT output is high for 3 PWM
cycles. If pulses are detected in this 3-cycle period, normal PWM operation is resumed and no fan fault is indicated. If no pulses are detected in the 3-cycle period,
the start-up timer is activated and the VOUT output is
driven high for 32 PWM cycles. If pulses are detected
during this time-frame, normal PWM operation is
resumed. If no pulses are detected during this timeperiod, a fan fault condition exists and the FAULT
output is pulled low.
During a fan fault condition, the FAULT output will
remain low until the fault condition has been removed.
During this time, the VOUT output is driven high continuously to attempt to restart the fan and the SENSE pin
is monitored for fan pulses. If a minimum of 16 pulses
are detected at the SENSE input over a 32 cycle timeperiod (one second for C F = 1.0 µF), the fan fault condition no longer exists. Therefore, The FAULT output is
released and the V OUT output returns to normal PWM
operation, as dictated by the VIN and VAS inputs.
FIGURE 4-6:
Fan Current With DC Offset
And Positive Commutation Current.
If the VIN voltage is pulled below the VSHDN level during
a fan fault condition, the FAULT output will be released
and the VOUT output will be shutdown (VOUT = 0V). If
the VIN voltage then increases above the VREL threshold and is above the VAS voltage, the device will go
through the normal start-up routine.
If, during a fan fault condition, the voltage at the V IN pin
drops below the VAS voltage level, the TC646B/
TC649B device will continue to hold the FAULT line low
and drive the V OUT output to 100% duty cycle. If the fan
fault condition is then removed, the FAULT output will
be released and the TC646B/TC649B device will enter
auto-shutdown mode until the V IN voltage is brought
above the VAS voltage by the auto-shutdown hysteresis
value (VHAS). The TC646B/TC649B device will then
resume normal PWM mode operation.
The sink current capability of the FAULT output is listed
in the “Electrical Characteristics Table” of Section 1.0.
DS21755B-page 14
FIGURE 4-7:
Fan Current With
Commutation Pulses To Zero.
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
The SENSE pin senses positive voltage pulses that
have an amplitude of 70 mV (typical value). Each time
a pulse is detected, the missing pulse detector timer
(tMP) is reset. As previously stated, if the missing pulse
detector timer reaches the time for 32 cycles, the loop
for diagnosing a fan fault is engaged (diagnostic timer,
then the start-up timer).
Both of the fan current waveshapes shown in Figures
4-6 and 4-7 can be sensed with the sensing scheme
shown in Figure 4-8.
The initial pulse blanker is also implemented to stop
false sensing of fan current pulses. When a fan is in a
locked rotor condition, the fan current no longer commutates, it simply flows through one fan winding and is
a DC current. When a fan is in a locked rotor condition
and the TC646B/TC649B device is in PWM mode, it
will see one current pulse each time the VOUT output is
turned on. The initial pulse blanker allows the
TC646B/TC649B device to ignore this pulse and
recognize that the fan is in a fault condition.
4.9
FAN
TC64XB
RISO
VOUT
SENSE
GND
FIGURE 4-8:
Current.
Behavioral Algorithms
The behavioral algorithms for the TC646B/TC649B
and TC648B devices are shown in Figure 4-9 and
Figure 4-10, respectively.
The behavioral algorithms show the step-by-step decision-making process for the fan speed controller operation. The TC646B and TC649B devices are very
similar with one exception: the TC649B device does
not implement the over-temperature portion of the
algorithm.
CSENSE
(0.1 µF typical) RSENSE
Sensing Scheme For Fan
The fan current flowing through RSENSE generates a
voltage that is proportional to the current. The CSENSE
capacitor removes any DC portion of the voltage
across R SENSE and presents only the voltage pulse
portion to the SENSE pin of the TC646B/TC649B
devices.
The RSENSE and CSENSE values need to be selected so
that the voltage pulse provided to the SENSE pin is
70 mV (typical) in amplitude. Be sure to check the
sense pulse amplitude over all operating conditions
(duty cycles) as the current pulse amplitude will vary
with duty cycle. See Section 5.0, “Applications Information”, for more details on selecting values for RSENSE
and CSENSE.
Key features of the SENSE pin circuitry are an initial
blanking period after every VOUT pulse and an initial
pulse blanker.
The TC646B/TC649B sense circuitry has a blanking
period that occurs at the turn-on of each VOUT pulse.
During this blanking period, the sense circuitry ignores
any pulse information that is seen at the SENSE pin
input. This stops the TC646B/TC649B device from
falsely sensing a current pulse that is due to the fan
drive device turn-on.
 2003 Microchip Technology Inc.
DS21755B-page 15
TC646B/TC648B/TC649B
Power-Up
Normal
Operation
Power-on
Reset
FAULT = 1
Clear Missing
Pulse Detector
Yes
VIN < VSHDN?
Shutdown
VOUT = 0
No
Yes
VIN > VREL ?
No
No
VIN > VREL?
Yes
Yes
VIN < VAS?
Yes
VIN < VAS?
AutoShutdown
VOUT = 0
Auto
Shutdown
VOUT = 0
No
No
VIN > VOTF?
Yes
Hot Start
Yes
Power-Up
Yes
Yes
Hot Start
FAULT = 0
Fire Start-up
Timer
(1 sec)
Fan Pulse
Detected?
No
VIN >
No
(VAS + VHAS)
No
VIN>
(VAS+ VHAS)
Shutdown
VOUT = 0
VIN < VSHDN?
No
No
VOUT
Proportional
to VIN
Fire Start-up
Timer
(1 sec)
Yes
Yes
Yes
Normal
Operation
Fan Pulse
Detected?
Fan Pulse
Detected?
No
TC646B Only
No
M.P.D.
Expired?
Yes
No
Fire
Diagnostic
Timer
(100 msec)
Fan Fault
Fan Fault
Yes
FAULT = Low,
VOUT = High
Fan Pulse
Detected?
No Fire Start-up
Timer
(1 sec)
Yes
VIN < VSHDN?
Yes
Fan Pulse
Detected?
No
Shutdown
VOUT = 0
Fan Fault
No
No
No
16 Pulses
Detected?
VIN > VREL?
Yes
Power-Up
Yes
Normal
Operation
FIGURE 4-9:
DS21755B-page 16
TC646B/TC649B Behavioral Algorithm.
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
Normal
Operation
Power-Up
VOUT
Proportional
to VIN
Power-on
Reset
OTF = 1
Yes
VAS = 0V
Minimum
Speed Mode
Yes
No
VIN > VOTF ?
No
OTF = 0
Yes
VIN < VAS?
OTF = 1
AutoShutdown
VOUT = 0
No
VIN >
(VAS+ VHAS)
Auto
Shutdown
VOUT = 0
No
Yes
VIN < VAS?
No
Yes
Fire Start-up
Timer
(1 sec)
Normal
Operation
Minimum
Speed Mode
Yes
VOUT = 0
VIN = 0V
No
No
VIN > 1.20V
VIN > 1.20V
No
VOUT = 0
Yes
Power-Up
VOUT
Proportional
to VIN
Yes
Yes
VIN > VOTF?
No
OTF = 0
FIGURE 4-10:
OTF = 1
TC648B Behavioral Algorithm.
 2003 Microchip Technology Inc.
DS21755B-page 17
TC646B/TC648B/TC649B
5.0
APPLICATIONS INFORMATION
5.1
Setting the PWM Frequency
One of the simplest ways of sensing temperature over
a given range is to use a thermistor. By using a NTC
thermistor, as shown in Figure 5-1, a temperaturevariant voltage can be created.
The PWM frequency of the VOUT output is set by the
capacitor value attached to the CF pin. The PWM frequency will be 30 Hz (typical) for a 1 µF capacitor. The
relationship between frequency and capacitor value is
linear, making alternate frequency selections easy.
As stated in previous sections, the PWM frequency
should be kept in the range of 15 Hz to 35 Hz. This will
eliminate the possibility of having audible frequencies
when varying the duty cycle of the fan drive.
A very important factor to consider when selecting the
PWM frequency for the TC646B/TC648B/TC649B
devices is the RPM rating of the selected fan and the
minimum duty cycle that you will be operating at. For
fans that have a full-speed rating of 3000 RPM or less,
it is desirable to use a lower PWM frequency. A lower
PWM frequency allows for a longer time-period to monitor the fan current pulses. The goal is to be able to
monitor at least two fan current pulses during the ontime of the VOUT output.
Example: The system design requirement is to operate
the fan at 50% duty cycle when ambient temperatures
are below 20°C. The fan full-speed RPM rating is
3000 RPM and has four current pulses per rotation. At
50% duty cycle, the fan will be operating at
approximately 1500 RPM.
EQUATION
× 1000- = 40
Time for one revolution (msec.) = 60
----------------------1500
If one fan revolution occurs in 40 msec, each fan pulse
occurs 10 msec apart. In order to detect two fan current
pulses, the on-time of the VOUT pulse must be at least
20 msec. With the duty cycle at 50%, the total period of
one cycle must be at least 40 msec, which makes the
PWM frequency 25 Hz. For this example, a PWM frequency of 20 Hz is recommended. This would define a
CF capacitor value of 1.5 µF.
5.2
Temperature Sensor Design
As discussed in previous sections, the VIN analog input
has a range of 1.20V to 2.60V (typical), which represents a duty cycle range on the VOUT output of 0% to
100%, respectively. The VIN voltages can be thought of
as representing temperatures. The 1.20V level is the
low temperature at which the system requires very little
cooling. The 2.60V level is the high temperature, for
which the system needs maximum cooling capability
(100% fan speed).
DS21755B-page 18
VDD
IDIV
RT
R1
VIN
R2
FIGURE 5-1:
Circuit.
Temperature Sensing
Figure 5-1 represents a temperature-dependent, voltage divider circuit. RT is a conventional NTC thermistor,
R 1 and R2 are standard resistors. R1 and RT form a
parallel resistor combination that will be referred to as
RTEMP (RTEMP = R1 * RT / R1 + RT). As the temperature
increases, the value of RT decreases and the value of
RTEMP will decrease with it. Accordingly, the voltage at
VIN increases as temperature increases, giving the
desired relationship for the VIN input. R1 helps to linearize the response of the SENSE network and aids in
obtaining the proper VIN voltages over the desired temperature range. An example of this is shown in
Figure 5-2.
If less current draw from VDD is desired, a larger value
thermistor should be chosen. The voltage at the VIN pin
can also be generated by a voltage output temperature
sensor device. The key is to get the desired VIN voltage-to-system (or component) temperature relationship.
The following equations apply to the circuit in
Figure 5-1.
EQUATION
V DD × R 2
V ( T1 ) = --------------------------------------------R TEMP ( T1 ) + R 2
V DD × R 2
V ( T2 ) = --------------------------------------------R TEMP ( T2 ) + R 2
In order to solve for the values of R1, R2, VIN and the
temperatures at which they are to occur, need to be
selected. The variables T1 and T2 represent the
selected temperatures. The value of the thermistor at
these two temperatures can be found in the thermistor
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
data sheet. With the values for the thermistor and the
values for VIN, you now have two equations from which
the values for R 1 and R 2 can be found.
Example: The following design goals are desired:
• Duty Cycle = 50% (VIN = 1.90V) with Temperature
(T1) = 30°C
• Duty Cycle = 100% (VIN = 2.60V) with
Temperature (T2) = 60°C
Using a 100 kΩ thermistor (25°C value), we look up the
thermistor values at the desired temperatures:
• RT (T1) = 79428Ω @ 30°C
• RT (T2) = 22593Ω @ 60°C
Substituting these numbers into the given equations
produces the following numbers for R 1 and R 2.
• R1 = 34.8 kΩ
• R2 = 14.7 kΩ
FanSense Network
(RSENSE and CSENSE)
The SENSE network (comprised of RSENSE and
CSENSE) allows the TC646B and TC649B devices to
detect commutation of the fan motor. RSENSE converts
the fan current into a voltage. CSENSE AC couples this
voltage signal to the SENSE pin. The goal of the
SENSE network is to provide a voltage pulse to the
SENSE pin that has a minimum amplitude of 90 mV.
This will ensure that the current pulse caused by the
fan commutation is recognized by the TC646B/
TC649B device.
A 0.1 µF ceramic capacitor is recommended for
CSENSE. Smaller values will require that larger sense
resistors be used. Using a 0.1 µF capacitor results in
reasonable values for RSENSE. Figure 5-3 illustrates a
typical SENSE network.
4.000
FAN
3.500
VIN Voltage
120
3.000
100
2.500
80
2.000
60
NTC Thermistor
100 k: @ 25ºC
40
20
0
30
40
50
60
70
80
90
VOUT
RISO
715Ω
1.500
1.000
0.500
RTEMP
20
VIN (V)
Network Resistance (k:)
140
5.4
SENSE
0.000
100
CSENSE
(0.1 µF typical)
RSENSE
Temperature (ºC)
Note:
FIGURE 5-2:
How Thermistor Resistance,
VIN, and RTEMP Vary With Temperature.
Figure 5-2 graphs RT, RTEMP (R1 in parallel with RT)
and VIN, versus temperature for the example shown
above.
5.3
Thermistor Selection
As with any component, there are a number of sources
for thermistors. A listing of companies that manufacture
thermistors can be found at www.temperatures.com/
thermivendors.html. This website lists over forty
suppliers of thermistor products. A brief list is shown
here:
-
Thermometrics®
®
-
Quality Thermistor™
-
Sensor Scientific™
-
Ametherm
-
U.S. Sensor™
-
Vishay®
-
Advanced Thermal
Products™
-
muRata®
 2003 Microchip Technology Inc.
FIGURE 5-3:
See Table 5-1 for R SENSE values.
Typical Sense Network.
The required value of RSENSE will change with the current rating of the fan and the fan current waveshape. A
key point is that the current rating of the fan specified
by the manufacturer may be a worst-case rating, with
the actual current drawn by the fan being lower than
this rating. For the purposes of setting the value for
RSENSE, the operating fan current should be measured
to get the nominal value. This can be done by using an
oscilloscope current probe or using a voltage probe
with a low-value resistor (0.5Ω). Another good tool for
this exercise is the TC642 Evaluation Board. This
board allows the RSENSE and CSENSE values to be easily changed while allowing the voltage waveforms to be
monitored to ensure the proper levels are being
reached.
Table 5-1 shows values of RSENSE according to the
nominal operating current of the fan. The fan currents
are average values. If the fan current falls between two
of the values listed, use the higher resistor value.
DS21755B-page 19
TC646B/TC648B/TC649B
TABLE 5-1:
FAN CURRENT VS. R SENSE
Nominal Fan Current
(mA)
RSENSE (Ω)
50
9.1
100
4.7
150
3.0
200
2.4
250
2.0
300
1.8
350
1.5
400
1.3
450
1.2
500
1.0
The values listed in Table 5-1 are for fans that have the
fan current waveshape shown in Figure 4-7. With this
waveshape, the average fan current is closer to the
peak value, which requires the resistor value to be
higher. When using a fan that has the fan current waveshape shown in Figure 4-6, the resistor value can often
be decreased since the current peaks are higher than
the average and it is the AC portion of the voltage that
gets coupled to the SENSE pin.
The key point when selecting an RSENSE value is to try
to minimize the value in order to minimize the power
dissipation in the resistor. In order to do this, it is critical
to know the waveshape of the fan current and not just
the average value.
Figure 5-4 shows some typical waveforms for the fan
current and the voltage at the SENSE pin.
Another important factor to consider when selecting the
R SENSE value is the fan current value during a lockedrotor condition. When a fan is in a locked-rotor condition (fan blades are stopped even though power is
being applied to the fan), the fan current can increase
dramatically (often 2.5 to 3.0 times the normal operating fan current). This will effect the power rating of the
R SENSE resistor selected.
When selecting the fan for the application, the current
draw of the fan during a locked-rotor condition should
be considered. Especially if multiple fans are being
used in the application.
There are two main types of fan designs when looking
at fan current draw during a locked-rotor condition.
The first is a fan that will simply draw high DC currents
when put into a locked-rotor condition. Many older fans
were designed this way. An example of this is a fan that
draws an average current of 100 mA during normal
operation. In a locked-rotor condition, this fan will draw
250 mA of average current. For this design, the
R SENSE power rating must be sized to handle the
250 mA condition. The fan bias supply must also take
this into account.
The second style design, which represents many of the
newer fan designs today, acts to limit the current in a
locked-rotor condition by going into a pulse mode of
operation. An example of the fan current waveshape
for this style fan is shown in Figure 5-5. The fan represented in Figure 5-5 is a Panasonic®, 12V, 220 mA fan.
During the on-time of the waveform, the fan current is
peaking up to 550 mA. Due to the pulse mode operation, the actual RMS current of the fan is very near the
220 mA rating. Because of this, the power rating for the
R SENSE resistor does not have to be oversized for this
application.
FIGURE 5-4:
Typical Fan Current and
SENSE Pin Waveforms.
DS21755B-page 20
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
FIGURE 5-5:
5.5
Fan Current During a Locked Rotor Condition.
Output Drive Device Selection
The TC646B/TC648B/TC649B is designed to drive an
external NPN transistor or N-channel MOSFET as the
fan speed modulating element. These two arrangements are shown in Figure 5-7. For lower-current fans,
NPN transistors are a very economical choice for the
fan drive device. It is recommended that, for higher current fans (300 mA and above), MOSFETs be used as
the fan drive device. Table 5-2 provides some possible
part numbers for use as the fan drive element.
The following is recommended:
• Ask how the fan is designed. If the fan has clamp
diodes internally, this problem will not be seen. If
the fan does not have internal clamp diodes, it is a
good idea to install one externally (Figure 5-6).
Putting a resistor between VOUT and the gate of
the MOSFET will also help slow down the turn-off
and limit this condition.
When using a NPN transistor as the fan drive element,
a base current-limiting resistor must be used. This is
shown in Figure 5-7.
When using MOSFETs as the fan drive element, it is
very easy to turn the MOSFETs on and off at very high
rates. Because the gate capacitances of these small
MOSFETs are very low, the TC646B/TC648B/TC649B
can charge and discharge them very quickly, leading to
very fast edges. Of key concern is the turn-off edge of
the MOSFET. Since the fan motor winding is essentially
an inductor, once the MOSFET is turned off the current
that was flowing through the motor wants to continue to
flow. If the fan does not have internal clamp diodes
around the windings of the motor, there is no path for
this current to flow through and the voltage at the drain
of the MOSFET may rise until the drain-to-source rating
of the MOSFET is exceeded. This will most likely cause
the MOSFET to go into avalanche mode. Since there is
very little energy in this occurrence, it will probably not
fail the device, but it would be a long-term reliability
issue.
 2003 Microchip Technology Inc.
FAN
VOUT
Q1
RSENSE
GND
Q1: N-Channel MOSFET
FIGURE 5-6:
Off.
Clamp Diode For Fan Turn-
DS21755B-page 21
TC646B/TC648B/TC649B
VOUT
Fan Bias
Fan Bias
FAN
FAN
RBASE
Q1
Q1
VOUT
RSENSE
RSENSE
GND
GND
a) Single Bipolar Transistor
FIGURE 5-7:
TABLE 5-2:
b) N-Channel MOSFET
Output Drive Device Configurations.
FAN DRIVE DEVICE SELECTION TABLE (NOTE 2)
Device
Package
Max Vbe sat /
Vgs(V)
Min hfe
VCE/VDS
(V)
Fan Current
(mA)
Suggested
Rbase (Ω)
MMBT2222A
SOT-23
1.2
50
40
150
800
MPS2222A
TO-92
1.2
50
40
150
800
MPS6602
TO-92
1.2
50
40
500
301
SI2302
SOT-23
2.5
NA
20
500
Note 1
MGSF1N02E
SOT-23
2.5
NA
20
500
Note 1
SI4410
SO-8
4.5
NA
30
1000
Note 1
SI2308
SOT-23
4.5
NA
60
500
Note 1
Note 1:
2:
5.6
A series gate resistor may be used in order to control the MOSFET turn-on and turn-off times.
These drive devices are suggestions only. Fan currents listed are for individual fans.
Bias Supply Bypassing and Noise
Filtering
The bias supply (VDD) for the TC646B/TC648B/
TC649B devices should be bypassed with a 1.0 µF
ceramic capacitor. This capacitor will help supply the
peak currents that are required to drive the base/gate
of the external fan drive devices.
As the VIN pin controls the duty cycle in a linear fashion,
any noise on this pin can cause duty cycle jittering. For
this reason, the VIN pin should be bypassed with a
0.01 µF capacitor.
In order to keep fan noise off of the TC646B/TC648B/
TC649B device ground, individual ground returns for
the TC646B/TC648B/TC649B and the low side of the
fan current sense resistor should be used.
DS21755B-page 22
5.7
Design Example/Typical
Application
The system has been designed with the following
components and criteria:
System inlet air ambient temperature ranges from 0ºC
to 50ºC. At 20ºC, system cooling is no longer required,
so the fan is to be turned off. Prior to turn-off, the fan
should be run at 40% of its full fan speed. Full fan
speed should be reached when the ambient air is 40ºC.
The system has a surface mount, NTC-style thermistor
in a 1206 package. The thermistor is mounted on a
daughtercard that is directly in the inlet air stream. The
thermistor is a NTC, 100 kΩ @ 25ºC, Thermometrics®
part number NHQ104B425R5. The given Beta for the
thermistor is 4250. The system bias voltage to run the
fan controller is 5V, while the fan voltage is 12V.
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
The fan used in the system is a Panasonic®, Panaflo®series fan, model number FBA06T12H.
A fault indication is desired when the fan is in a lockedrotor condition. This signal is used to indicate to the
system that cooling is not available and a warning
should be issued to the user. No fault indication from
the fan controller is necessary for an over-temperature
condition as this is being reported elsewhere.
Step 1: Gathering Information.
The first step in the design process is to gather the
needed data on the fan and thermistor. For the fan, it is
also a good idea to look at the fan current waveform, as
indicated earlier in the data sheet.
Fan Information: Panasonic number: FBA06T12H
- Voltage = 12V
- Current = 145 mA (data sheet number)
FIGURE 5-9:
Fan Current.
FBA06T12H Locked-Rotor
From Figure 5-9, it is seen that in a locked-rotor fault
condition, the fan goes into a pulsed current mode of
operation. During this mode, when the fan is conducting current, the peak current value is 360 mA for periods of 200 msec. This is significantly higher than the
average full fan speed current shown in Figure 5-8.
However, because of the pulse mode, the average fan
current in a locked-rotor condition is lower and was
measured at 68 mA. The RMS current during this
mode, which is necessary for current sense resistor
(RSENSE) value selection, was measured at 154 mA.
This is slightly higher than the RMS value during full fan
speed operation.
FIGURE 5-8:
Waveform.
FBA06T12H Fan Current
From the waveform in Figure 5-8, the fan current has
an average value of 120 mA, with peaks up to 150 mA.
This information will help in the selection of the RSENSE
and CSENSE values later on. Also of interest for the
RSENSE selection value is what the fan current does in
a locked-rotor condition.
Thermistor Information: Thermometrics part number:
NHQ104B425R5
- Resistance Value: 100 kΩ @ 25ºC
- Beta Value (β): 4250
From this information, the thermistor values at 20ºC
and 40ºC must be found. This information is needed in
order to select the proper resistor values for R1 and R2
(see Figure 5-13), which sets the VIN voltage.
The equation for determining the thermistor values is
shown below:
EQUATION
β( TO – T )
R T = R TO exp -----------------------T • TO
RT0 is the thermistor value at 25ºC. T0 is 298.15 and T
is the temperature of interest. All temperatures are in
degrees kelvin.
Using this equation, the values for the thermistor are
found to be:
- RT (20ºC) = 127,462Ω
- RT (40ºC) = 50,520Ω
 2003 Microchip Technology Inc.
DS21755B-page 23
TC646B/TC648B/TC649B
Step 3: Setting the PWM Frequency.
The fan is rated at 4200 RPM with a 12V input. The
goal is to run to a 40% duty cycle (roughly 40% fan
speed), which equates to approximately 1700 RPM. At
1700 RPM, one full fan revolution occurs every
35 msec. The fan being used is a four-pole fan that
gives four current pulses per revolution. With this information, and viewing test results at 40% duty cycle, two
fan current pulses were always seen during the PWM
on time with a PWM frequency of 30 Hz. For this reason, the CF value is selected to be 1.0 µF.
Step 4: Setting the VIN Voltage.
From the design criteria, the desired duty cycle at 20ºC
is 40% and full fan speed should be reached at 40ºC.
Based on a VIN voltage range of 1.20V to 2.60V, which
represents 0% to 100% duty cycle, the 40% duty cycle
voltage can be found using the following equation:
- R1 = 237 kΩ
- R2 = 45.3 kΩ
A graph of the VIN voltage, thermistor resistance and
RTEMP resistance versus temperature for this
configuration is shown in Figure 5-10.
400
5.00
4.50
350
4.00
VIN
300
3.50
250
3.00
200
2.50
150
2.00
NTC Thermistor
100 k: @ 25ºC
100
VIN (V)
The requirements for the fan controller are that it have
auto-shutdown capability at 20ºC and also indicate a
fan fault condition. No over-temperature indication is
necessary. From these specifications, the proper
selection is the TC649B device.
Using standard 1% resistor values, the selected R1 and
R 2 values are:
Network Resistance (k:)
Step 2: Selecting the Fan Controller.
1.50
1.00
50
RTEMP
0.50
0
0.00
0
10
20
30
40
50
60
70
80
90
Temperature (ºC)
FIGURE 5-10:
Thermistor Resistance, VIN
and RTEMP vs. Temperature
Step 5: Setting the Auto-Shutdown Voltage (VAS).
EQUATION
VIN = (DC * 1.4V) + 1.20V
DC = Desired Duty Cycle
Using the above equation, the VIN values are
calculated to be:
- VIN (40%) = 1.76V
- VIN (100%) = 2.60V
Using these values along with the thermistor resistance
values calculated earlier, the R 1 and R2 resistor values
can now be calculated using the following equation:
EQUATION
Setting the voltage for the auto-shutdown is done using
a simple resistor voltage divider. The criteria for the
voltage divider in this design is that it draw no more
than 100 µA of current. The required auto-shutdown
voltage was determined earlier in the selection of the
VIN voltage at 40% duty cycle, since this was also set
at the temperature that auto-shutdown is to occur
(20ºC).
- VAS = 1.76V
Given this desired setpoint and knowing the desired
divider current, the following equations can be used to
solve for the resistor values for R3 and R4:
EQUATION
V DD × R 2
V ( T1 ) = ----------------------------------------R TEMP ( T1 ) + R 2
IDIV =
V DD × R 2
V ( T2 ) = ----------------------------------------R TEMP ( T2 ) + R 2
VAS =
RTEMP is the parallel combination of R 1 and the thermistor. V(T1) represents the VIN voltage at 20ºC and
V(T2) represents the VIN voltage at 40ºC. Solving the
equations simultaneously yields the following values
(VDD = 5V):
- R1 = 238,455 Ω
- R2 = 45,161 Ω
DS21755B-page 24
5V
R3 + R 4
5V * R4
R3 + R 4
Using the equations above, the resistor values for R3
and R4 are found to be:
- R3 = 32.4 kΩ
- R4 = 17.6 kΩ
Using standard 1% resistor values yields the following
values:
- R3 = 32.4 kΩ
- R4 = 17.8 kΩ
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
Step 6: Selecting the Fan Drive Device (Q 1).
Since the fan operating current is below 200 mA, a
transistor or MOSFET can be used as the fan drive
device. In order to reduce component count and current draw, the drive device for this design is chosen to
be a N-channel MOSFET. Selecting from Table 5-2,
there are two MOSFETs that are good choices, the
MGSF1N02E and the SI2302. These devices have the
same pinout and are interchangeable for this design.
Step 7: Selecting the R SENSE and CSENSE Values.
The goal again for selecting these values is to ensure
that the signal at the SENSE pin is 90 mV in amplitude
under all operating conditions. This will ensure that the
pulses are detected by the TC649B device and that the
fan operation is detected.
The fan current waveform is shown in Figure 5-8, and
as discussed previously, with a waveform of this shape,
the current sense resistor values shown in Table 5-1 are
good reference values. Given the average fan operating
current was measured to be 120 mA, this falls between
two of the values listed in the table. For reference purposes, both values have been tested and these results
are shown in Figures 5-11 (4.7Ω) and 5-12 (3.0Ω). The
selected CSENSE value is 0.1 µF, as this provides the
appropriate coupling of the voltage to the SENSE pin.
FIGURE 5-12:
SENSE pin voltage with
3.0Ω sense resistor.
Since the 3.0Ω value of sense resistor provides the
proper voltage to the SENSE pin, it is the correct choice
for this solution as it will also provide the lowest power
dissipation and the maximum amount of voltage to the
fan. Using the RMS fan current which was measured
previously, the power dissipation in the resistor during
a fan fault condition is 71 mW (Irms2 * RSENSE). This
number will set the wattage rating of the resistor that is
selected. The selected value will vary depending upon
the derating guidelines that are used.
Now that all the values have been selected, the schematic representation of this design can be seen in
Figure 5-13.
FIGURE 5-11:
SENSE pin voltage with
4.7Ω sense resistor.
 2003 Microchip Technology Inc.
DS21755B-page 25
TC646B/TC648B/TC649B
+5V
+C
®
R1
237 kΩ
Thermometrics
100 kΩ @25°C
NHQ104B425R5
1V
CB
0.01 µF
R2
45.3kΩ
IN
+12V
VDD
1.0 µF
8
VDD
R5
10 kΩ
FAULT
Panasonic®
Fan 12V, 140 mA
FBA06T12H
6
+5V
R3
32.4 kΩ
R4
17.8 kΩ
FIGURE 5-13:
3 V
AS
CB
0.01 µF
2 C
F
CF
1.0 µF
TC649B
SENSE
GND
4
Q1
SI2302
or
MGSF1N02E
VOUT 7
5
CSENSE
0.1 µF
RSENSE
3.0Ω
Design Example Schematic.
Bypass capacitor CVDD is added to the design to
decouple the bias voltage. This is good to have, especially when using a MOSFET as the drive device. This
helps to give a localized low-impedance source for the
current required to charge the gate capacitance of Q1.
Two other bypass capacitors (labeled as C B) were also
added to decouple the V IN and VAS nodes. These were
added simply to remove any noise present that might
cause false triggerings or PWM jitter. R 5 is the pull-up
resistor for the FAULT output. The value for this resistor
is system-dependent.
DS21755B-page 26
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
6.0
PACKAGING INFORMATION
6.1
Package Marking Information
8-Lead PDIP (300 mil)
XXXXXXXXX
NNN
YYWW
8-Lead SOIC (150 mil)
XXXXXX
XXXYYWW
NNN
8-Lead MSOP
XXXXXX
YWWNNN
Legend: XX...X
Y
YY
WW
NNN
Note:
*
Example :
TC646BCPA
025
0215
Example :
TC646B
COA0215
025
Example:
TC646B
215025
Customer specific information*
Year code (last digit of calendar year)
Year code (last 2 digits of calendar year)
Week code (week of January 1 is week ‘01’)
Alphanumeric traceability code
In the event the full Microchip part number cannot be marked on one line, it will
be carried over to the next line thus limiting the number of available characters
for customer specific information.
Standard device marking consists of Microchip part number, year code, week code, and traceability
code.
 2003 Microchip Technology Inc.
DS21755B-page 27
TC646B/TC648B/TC649B
8-Lead Plastic Dual In-line (PA) – 300 mil (PDIP)
E1
D
2
n
1
α
E
A2
A
L
c
A1
β
B1
p
eB
B
Units
Dimension Limits
n
p
Number of Pins
Pitch
Top to Seating Plane
Molded Package Thickness
Base to Seating Plane
Shoulder to Shoulder Width
Molded Package Width
Overall Length
Tip to Seating Plane
Lead Thickness
Upper Lead Width
Lower Lead Width
Overall Row Spacing
Mold Draft Angle Top
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
A
A2
A1
E
E1
D
L
c
§
B1
B
eB
α
β
MIN
.140
.115
.015
.300
.240
.360
.125
.008
.045
.014
.310
5
5
INCHES*
NOM
MAX
8
.100
.155
.130
.170
.145
.313
.250
.373
.130
.012
.058
.018
.370
10
10
.325
.260
.385
.135
.015
.070
.022
.430
15
15
MILLIMETERS
NOM
8
2.54
3.56
3.94
2.92
3.30
0.38
7.62
7.94
6.10
6.35
9.14
9.46
3.18
3.30
0.20
0.29
1.14
1.46
0.36
0.46
7.87
9.40
5
10
5
10
MIN
MAX
4.32
3.68
8.26
6.60
9.78
3.43
0.38
1.78
0.56
10.92
15
15
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-001
Drawing No. C04-018
DS21755B-page 28
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
8-Lead Plastic Small Outline (OA) – Narrow, 150 mil (SOIC)
E
E1
p
D
2
B
n
1
h
α
45×
c
A2
A
f
β
L
Units
Dimension Limits
n
p
Number of Pins
Pitch
Overall Height
Molded Package Thickness
Standoff §
Overall Width
Molded Package Width
Overall Length
Chamfer Distance
Foot Length
Foot Angle
Lead Thickness
Lead Width
Mold Draft Angle Top
Mold Draft Angle Bottom
* Controlling Parameter
§ Significant Characteristic
A
A2
A1
E
E1
D
h
L
f
c
B
α
β
MIN
.053
.052
.004
.228
.146
.189
.010
.019
0
.008
.013
0
0
A1
INCHES*
NOM
8
.050
.061
.056
.007
.237
.154
.193
.015
.025
4
.009
.017
12
12
MAX
.069
.061
.010
.244
.157
.197
.020
.030
8
.010
.020
15
15
MILLIMETERS
NOM
8
1.27
1.35
1.55
1.32
1.42
0.10
0.18
5.79
6.02
3.71
3.91
4.80
4.90
0.25
0.38
0.48
0.62
0
4
0.20
0.23
0.33
0.42
0
12
0
12
MIN
MAX
1.75
1.55
0.25
6.20
3.99
5.00
0.51
0.76
8
0.25
0.51
15
15
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed
.010” (0.254mm) per side.
JEDEC Equivalent: MS-012
Drawing No. C04-057
 2003 Microchip Technology Inc.
DS21755B-page 29
TC646B/TC648B/TC649B
8-Lead Plastic Micro Small Outline Package (UA) (MSOP)
E
E1
p
D
2
B
n
1
α
A2
A
c
φ
A1
(F)
L
β
Units
Dimension Limits
n
p
MIN
INCHES
NOM
MAX
MILLIMETERS*
NOM
8
0.65 BSC
0.75
0.85
0.00
4.90 BSC
3.00 BSC
3.00 BSC
0.40
0.60
0.95 REF
0°
0.08
0.22
5°
5°
-
MIN
8
Number of Pins
.026 BSC
Pitch
A
.043
Overall Height
A2
.030
.033
.037
Molded Package Thickness
A1
.000
.006
Standoff
E
.193 TYP.
Overall Width
E1
.118 BSC
Molded Package Width
D
.118 BSC
Overall Length
L
.016
.024
.031
Foot Length
Footprint (Reference)
F
.037 REF
φ
Foot Angle
0°
8°
c
Lead Thickness
.003
.006
.009
B
.009
.012
.016
Lead Width
α
5°
15°
Mold Draft Angle Top
β
5°
15°
Mold Draft Angle Bottom
*Controlling Parameter
Notes:
Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not
exceed .010" (0.254mm) per side.
MAX
1.10
0.95
0.15
0.80
8°
0.23
0.40
15°
15°
JEDEC Equivalent: MO-187
Drawing No. C04-111
DS21755B-page 30
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
6.2
Taping Form
Component Taping Orientation for 8-Pin MSOP Devices
User Direction of Feed
PIN 1
W
P
Standard Reel Component Orientation
for 713 or TR Suffix Device
Carrier Tape, Number of Components Per Reel and Reel Size:
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
8-Pin MSOP
12 mm
8 mm
2500
13 in.
Component Taping Orientation for 8-Pin SOIC Devices
User Direction of Feed
PIN 1
W
P
Standard Reel Component Orientation
for 713 or TR Suffix Device
Carrier Tape, Number of Components Per Reel and Reel Size:
Package
Carrier Width (W)
Pitch (P)
Part Per Full Reel
Reel Size
8-Pin SOIC
12 mm
8 mm
2500
13 in.
 2003 Microchip Technology Inc.
DS21755B-page 31
TC646B/TC648B/TC649B
NOTES:
DS21755B-page 32
 2003 Microchip Technology Inc.
TC646B/TC648B/TC649B
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
Device
Device:
X
/XX
Temperature
Range
Package
TC646B: PWM Fan Speed Controller with Fan
Restart, Auto-Shutdown, Fan Fault and
Over-Temp Detection
TC648B: PWM Fan Speed Controller with AutoShutdown and Over-Temp Detection
TC649B: PWM Fan Speed Controller with Fan
Restart, Auto-Shutdown and Fan Fault
Detection
Examples:
a)
b)
c)
d)
a)
b)
c)
d)
TC648BEOA: SOIC package.
TC648BEPA: PDIP package.
TC648BEUA: MSOP package.
TC648BEUA713: Tape and Reel,
MSOP package.
TC649BEOA: SOIC package.
TC649BEOATR: Tape and Reel,
SOIC package.
TC649BEPA: PDIP package.
TC649BEUA: MSOP package
Temperature
Range:
E
= -40°C to +85°C
a)
b)
Package:
OA
PA
UA
713
=
=
=
=
c)
d)
Plastic SOIC, (150 mil Body), 8-lead
Plastic DIP (300 mil Body), 8-lead
Plastic Micro Small Outline (MSOP), 8-lead
Tape and Reel (SOIC and MSOP)
(TC646B and TC648B only)
TR = Tape and Reel (SOIC and MSOP) (TC649B
only)
TC646BEOA: SOIC package.
TC646BEOA713: Tape and Reel,
SOIC package.
TC646BEPA: PDIP package.
TC646BEUA: MSOP package.
Sales and Support
Data Sheets
Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and
recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following:
1.
2.
3.
Your local Microchip sales office
The Microchip Corporate Literature Center U.S. FAX: (480) 792-7277
The Microchip Worldwide Site (www.microchip.com)
Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using.
Customer Notification System
Register on our web site (www.microchip.com/cn) to receive the most current information on our products.
 2003 Microchip Technology Inc.
DS21755B-page 33
TC646B/TC648B/TC649B
NOTES:
DS21755B-page 34
 2003 Microchip Technology Inc.
Note the following details of the code protection feature on Microchip devices:
•
Microchip products meet the specification contained in their particular Microchip Data Sheet.
•
Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the
intended manner and under normal conditions.
•
There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our
knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip's Data
Sheets. Most likely, the person doing so is engaged in theft of intellectual property.
•
Microchip is willing to work with the customer who is concerned about the integrity of their code.
•
Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not
mean that we are guaranteeing the product as “unbreakable.”
Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our
products. Attempts to break microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts
allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act.
Information contained in this publication regarding device
applications and the like is intended through suggestion only
and may be superseded by updates. It is your responsibility to
ensure that your application meets with your specifications.
No representation or warranty is given and no liability is
assumed by Microchip Technology Incorporated with respect
to the accuracy or use of such information, or infringement of
patents or other intellectual property rights arising from such
use or otherwise. Use of Microchip’s products as critical
components in life support systems is not authorized except
with express written approval by Microchip. No licenses are
conveyed, implicitly or otherwise, under any intellectual
property rights.
Trademarks
The Microchip name and logo, the Microchip logo, KEELOQ,
MPLAB, PIC, PICmicro, PICSTART, PRO MATE and
PowerSmart are registered trademarks of Microchip
Technology Incorporated in the U.S.A. and other countries.
FilterLab, microID, MXDEV, MXLAB, PICMASTER, SEEVAL
and The Embedded Control Solutions Company are
registered trademarks of Microchip Technology Incorporated
in the U.S.A.
Accuron, Application Maestro, dsPIC, dsPICDEM,
dsPICDEM.net, ECONOMONITOR, FanSense, FlexROM,
fuzzyLAB, In-Circuit Serial Programming, ICSP, ICEPIC,
microPort, Migratable Memory, MPASM, MPLIB, MPLINK,
MPSIM, PICC, PICkit, PICDEM, PICDEM.net, PowerCal,
PowerInfo, PowerMate, PowerTool, rfLAB, rfPIC, Select
Mode, SmartSensor, SmartShunt, SmartTel and Total
Endurance are trademarks of Microchip Technology
Incorporated in the U.S.A. and other countries.
Serialized Quick Turn Programming (SQTP) is a service mark
of Microchip Technology Incorporated in the U.S.A.
All other trademarks mentioned herein are property of their
respective companies.
© 2003, Microchip Technology Incorporated, Printed in the
U.S.A., All Rights Reserved.
Printed on recycled paper.
Microchip received QS-9000 quality system
certification for its worldwide headquarters,
design and wafer fabrication facilities in
Chandler and Tempe, Arizona in July 1999
and Mountain View, California in March 2002.
The Company’s quality system processes and
procedures are QS-9000 compliant for its
PICmicro® 8-bit MCUs, KEELOQ® code hopping
devices, Serial EEPROMs, microperipherals,
non-volatile memory and analog products. In
addition, Microchip’s quality system for the
design and manufacture of development
systems is ISO 9001 certified.
DS21755B-page 35
 2003 Microchip Technology Inc.
M
WORLDWIDE SALES AND SERVICE
AMERICAS
ASIA/PACIFIC
Corporate Office
Australia
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7200 Fax: 480-792-7277
Technical Support: 480-792-7627
Web Address: http://www.microchip.com
Microchip Technology Australia Pty Ltd
Marketing Support Division
Suite 22, 41 Rawson Street
Epping 2121, NSW
Australia
Tel: 61-2-9868-6733 Fax: 61-2-9868-6755
Atlanta
3780 Mansell Road, Suite 130
Alpharetta, GA 30022
Tel: 770-640-0034 Fax: 770-640-0307
China - Beijing
2 Lan Drive, Suite 120
Westford, MA 01886
Tel: 978-692-3848 Fax: 978-692-3821
Microchip Technology Consulting (Shanghai)
Co., Ltd., Beijing Liaison Office
Unit 915
Bei Hai Wan Tai Bldg.
No. 6 Chaoyangmen Beidajie
Beijing, 100027, No. China
Tel: 86-10-85282100 Fax: 86-10-85282104
Chicago
China - Chengdu
333 Pierce Road, Suite 180
Itasca, IL 60143
Tel: 630-285-0071 Fax: 630-285-0075
Microchip Technology Consulting (Shanghai)
Co., Ltd., Chengdu Liaison Office
Rm. 2401-2402, 24th Floor,
Ming Xing Financial Tower
No. 88 TIDU Street
Chengdu 610016, China
Tel: 86-28-86766200 Fax: 86-28-86766599
Boston
Dallas
4570 Westgrove Drive, Suite 160
Addison, TX 75001
Tel: 972-818-7423 Fax: 972-818-2924
Detroit
Tri-Atria Office Building
32255 Northwestern Highway, Suite 190
Farmington Hills, MI 48334
Tel: 248-538-2250 Fax: 248-538-2260
Kokomo
2767 S. Albright Road
Kokomo, IN 46902
Tel: 765-864-8360 Fax: 765-864-8387
Los Angeles
18201 Von Karman, Suite 1090
Irvine, CA 92612
Tel: 949-263-1888 Fax: 949-263-1338
Phoenix
2355 West Chandler Blvd.
Chandler, AZ 85224-6199
Tel: 480-792-7966 Fax: 480-792-4338
San Jose
Microchip Technology Inc.
2107 North First Street, Suite 590
San Jose, CA 95131
Tel: 408-436-7950 Fax: 408-436-7955
Toronto
6285 Northam Drive, Suite 108
Mississauga, Ontario L4V 1X5, Canada
Tel: 905-673-0699 Fax: 905-673-6509
China - Fuzhou
Microchip Technology Consulting (Shanghai)
Co., Ltd., Fuzhou Liaison Office
Unit 28F, World Trade Plaza
No. 71 Wusi Road
Fuzhou 350001, China
Tel: 86-591-7503506 Fax: 86-591-7503521
China - Hong Kong SAR
Microchip Technology Hongkong Ltd.
Unit 901-6, Tower 2, Metroplaza
223 Hing Fong Road
Kwai Fong, N.T., Hong Kong
Tel: 852-2401-1200 Fax: 852-2401-3431
China - Shanghai
Microchip Technology Consulting (Shanghai)
Co., Ltd.
Room 701, Bldg. B
Far East International Plaza
No. 317 Xian Xia Road
Shanghai, 200051
Tel: 86-21-6275-5700 Fax: 86-21-6275-5060
China - Shenzhen
Microchip Technology Consulting (Shanghai)
Co., Ltd., Shenzhen Liaison Office
Rm. 1812, 18/F, Building A, United Plaza
No. 5022 Binhe Road, Futian District
Shenzhen 518033, China
Tel: 86-755-82901380 Fax: 86-755-82966626
China - Qingdao
Rm. B505A, Fullhope Plaza,
No. 12 Hong Kong Central Rd.
Qingdao 266071, China
Tel: 86-532-5027355 Fax: 86-532-5027205
India
Microchip Technology Inc.
India Liaison Office
Marketing Support Division
Divyasree Chambers
1 Floor, Wing A (A3/A4)
No. 11, O’Shaugnessey Road
Bangalore, 560 025, India
Tel: 91-80-2290061 Fax: 91-80-2290062
Japan
Microchip Technology Japan K.K.
Benex S-1 6F
3-18-20, Shinyokohama
Kohoku-Ku, Yokohama-shi
Kanagawa, 222-0033, Japan
Tel: 81-45-471- 6166 Fax: 81-45-471-6122
Korea
Microchip Technology Korea
168-1, Youngbo Bldg. 3 Floor
Samsung-Dong, Kangnam-Ku
Seoul, Korea 135-882
Tel: 82-2-554-7200 Fax: 82-2-558-5934
Singapore
Microchip Technology Singapore Pte Ltd.
200 Middle Road
#07-02 Prime Centre
Singapore, 188980
Tel: 65-6334-8870 Fax: 65-6334-8850
Taiwan
Microchip Technology (Barbados) Inc.,
Taiwan Branch
11F-3, No. 207
Tung Hua North Road
Taipei, 105, Taiwan
Tel: 886-2-2717-7175 Fax: 886-2-2545-0139
EUROPE
Austria
Microchip Technology Austria GmbH
Durisolstrasse 2
A-4600 Wels
Austria
Tel: 43-7242-2244-399
Fax: 43-7242-2244-393
Denmark
Microchip Technology Nordic ApS
Regus Business Centre
Lautrup hoj 1-3
Ballerup DK-2750 Denmark
Tel: 45-4420-9895 Fax: 45-4420-9910
France
Microchip Technology SARL
Parc d’Activite du Moulin de Massy
43 Rue du Saule Trapu
Batiment A - ler Etage
91300 Massy, France
Tel: 33-1-69-53-63-20 Fax: 33-1-69-30-90-79
Germany
Microchip Technology GmbH
Steinheilstrasse 10
D-85737 Ismaning, Germany
Tel: 49-89-627-144-0
Fax: 49-89-627-144-44
Italy
Microchip Technology SRL
Via Quasimodo, 12
20025 Legnano (MI)
Milan, Italy
Tel: 39-0331-742611 Fax: 39-0331-466781
United Kingdom
Microchip Ltd.
505 Eskdale Road
Winnersh Triangle
Wokingham
Berkshire, England RG41 5TU
Tel: 44-118-921-5869 Fax: 44-118-921-5820
03/25/03
DS21755B-page 36
 2003 Microchip Technology Inc.