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 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

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

OUT

SENSE

MIN

GND

FAULT

TC642B

TC647B

PWM Fan Speed Controllers With Minimum Fan Speed,

Fan Restart and FanSense™ Technology for Fault Detection

Summary of content (36 pages)

PAGE 1
TC642B/TC647B PWM Fan Speed Controllers With Minimum Fan Speed, 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.
PAGE 2
TC642B/TC647B Functional Block Diagram TC642B/TC647B VOTF VIN VDD Note Control Logic CF 3xTPWM Timer Clock Generator VMIN VSHDN DS21756C-page 2 VOUT Start-up Timer Missing Pulse Detect 10 k GND Note: The VOTF comparator is for the TC642B device only. FAULT SENSE 70 mV (typ)  2002-2013 Microchip Technology Inc.
PAGE 3
TC642B/TC647B 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) VMIN Analog Input Operating Temperature Range ....................- 40°C to +125°C GND Ground Maximum Junction Temperature, TJ ...........................
PAGE 4
TC642B/TC647B ELECTRICAL SPECIFICATIONS (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 Conditions 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 Output Low Voltage VOL — — 0.
PAGE 5
TC642B/TC647B TIMING SPECIFICATIONS tSTARTUP VOUT FAULT SENSE FIGURE 1-1: TC642B/TC647B Start-Up Timing. 33.3 msec (CF = 1 µF) tDIAG tMP tMP VOUT FAULT SENSE FIGURE 1-2: Fan Fault Occurrence. tMP VOUT FAULT Minimum 16 pulses SENSE FIGURE 1-3: Recovery From Fan Fault.  2002-2013 Microchip Technology Inc.
PAGE 6
TC642B/TC647B C2 1 µF C1 0.1 µF + - VDD 8 R1 + - VIN 1 C3 0.1 µF VIN VDD K3 VOUT R6 7 + R2 + - VMIN 3 C4 0.1 µF VMIN VDD TC642B TC647B R5 K4 FAULT 6 + - 2 CF GND K1 C7 .01 µF K2 C6 1 µF 4 C8 0.1 µF Current limited voltage source SENSE R4 5 R3 Current limited voltage source VSENSE (pulse voltage source) C5 0.1 µF Note: C5 and C7 are adjusted to get the necessary 1 µF value. FIGURE 1-4: DS21756C-page 6 TC642B/TC647B Electrical Characteristics Test Circuit.
PAGE 7
TC642B/TC647B 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.
PAGE 8
TC642B/TC647B Note: Unless otherwise indicated, VDD = 5V, TA = +25°C. 70 74.0 IOL = 2.5 mA 73.5 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 VOL (mV) 60 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 95 110 125 -40 -25 -10 5 Temperature (ºC) FIGURE 2-7: Temperature. 20 35 50 65 80 95 110 125 Temperature (ºC) FIGURE 2-10: Sense Threshold (VTH(SENSE)) vs. Temperature.
PAGE 9
TC642B/TC647B 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 -40 -25 -10 110 125 5 Temperature (ºC) FIGURE 2-13: Temperature. PWM Sink Current (IOL) vs. FIGURE 2-16: Temperature. 0.80 VOTF Hysteresis (mV) VDD = 5.5V 0.
PAGE 10
TC642B/TC647B 3.0 PIN FUNCTIONS 3.5 The description 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 3.1 Function 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).
PAGE 11
TC642B/TC647B 4.0 DEVICE OPERATION The TC642B/TC647B devices are a family of temperature proportional, PWM mode, fan speed controllers. Features of the family include minimum fan speed, fan auto-shutdown mode, fan auto-restart, remote shutdown, over-temperature indication and fan fault detection. The TC642B/TC647B family is slightly different from the original TC64X family, which includes the TC642, TC646, TC647, TC648 and TC649 devices.
PAGE 12
TC642B/TC647B 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.
PAGE 13
TC642B/TC647B If the voltage at the VIN pin falls below 1.76V, the duty cycle of the VOUT output will not decrease below the 40% value that is now set by the voltage at the VMIN pin. In this manner, the fan will continue to operate at 40% speed even when the temperature (voltage at VIN) continues to decrease. 100 90 Duty Cycle (%) 80 70 60 50 40 30 20 10 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). VIN voltage vs.
PAGE 14
TC642B/TC647B Clamp Diode FAN Q1 VOUT RSENSE GND Q1: N-Channel MOSFET FIGURE 4-5: 4.7 Clamp Diode for Fan. FAULT Output The FAULT output is an open-drain, active-low output. For the TC642B and TC647B devices, the FAULT output indicates when a fan fault condition has occurred. For the TC642B device, the FAULT output also indicates when an over-temperature (OTF) condition has occurred.
PAGE 15
TC642B/TC647B across RSENSE and presents only the voltage pulse portion to the SENSE pin of the TC642B/TC647B 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.
PAGE 16
TC642B/TC647B Power-Up Normal Operation Power-on Reset FAULT = 1 Clear Missing Pulse Detector Yes Shutdown VOUT = 0 VMIN < VSHDN? Yes No Shutdown VOUT = 0 VMIN < VSHDN? VMIN > VREL? No No VMIN > VREL? No Yes Yes Fire Start-up Timer (1 sec) VIN > VOTF? Fire Start-up Timer (1 sec) No Fan Pulse Detected? Yes Power-Up FAULT = 0 Yes No Yes Fan Pulse Detected? Normal Operation TC642B Only VOUT Proportional to Greater of VIN or VMIN No Fan Fault Yes Fan Pulse Detected? No No M.P.D.
PAGE 17
TC642B/TC647B 5.0 APPLICATIONS INFORMATION 5.1 Setting the PWM Frequency 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. VDD IDIV RT R1 VIN As stated in previous sections, the PWM frequency should be kept in the range of 15 Hz to 35 Hz.
PAGE 18
TC642B/TC647B Example: The following design goals are desired: • Duty Cycle = 50% (VIN = 1.90 V) with Temperature (T1) = 30°C • Duty Cycle = 100% (VIN = 2.60 V) with Temperature (T2) = 60°C Using a 100 k thermistor (25°C value), look up the thermistor values at the desired temperatures: • RT (T1) = 79428 @ 30°C • RT (T2) = 22593 @ 60°C Substituting these numbers into the given equations produces the following numbers for R1 and R2. • R1 = 34.8 k • R2 = 14.7 k 3.500 3.000 100 2.500 80 2.
PAGE 19
TC642B/TC647B TABLE 5-1: FAN CURRENT VS. RSENSE Nominal Fan Current (mA) RSENSE() 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.
PAGE 20
TC642B/TC647B FIGURE 5-5: 5.5 Fan Current During a Locked Rotor Condition. Output Drive Device Selection The TC642B/TC647B 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.
PAGE 21
TC642B/TC647B Fan Bias Fan Bias FAN FAN RBASE VOUT Q1 Q1 VOUT RSENSE RSENSE GND GND a) Single Bipolar Transistor FIGURE 5-7: TABLE 5-2: Device MMBT2222A b) N-Channel MOSFET Output Drive Device Configurations. FAN DRIVE DEVICE SELECTION TABLE (NOTE 2) Package Max Vbe sat / Vgs(V) Min hfe VCE/VDS (V) Fan Current (mA) Suggested Rbase () 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.
PAGE 22
TC642B/TC647B 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 locked rotor 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.
PAGE 23
TC642B/TC647B Step 3: Setting the PWM Frequency. The fan is rated at 4200 RPM with a 12V input. Since the goal is to run to a 40% duty cycle (roughly 40% fan speed), which equates to approximately 1700 RPM, we can assume one full fan revolution occurs every 35 msec. The fan being used is a four-pole fan that gives four current pulses per revolution. Knowing this 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.
PAGE 24
TC642B/TC647B Using standard 1% resistor values yields the following values: . - R3 = 32.4 k - R4 = 17.8 k Step 6: Selecting the Fan Drive Device (Q1). 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.
PAGE 25
TC642B/TC647B +5V R1 237 k 1V IN CB 0.01 µF 8 VDD Panasonic® Fan 12V, 140 mA FBA06T12H R5 10 k FAULT R2 45.3 k +12V +C VDD 1.0 µF Thermometrics® 100 k @25°C NHQ104B425R5 6 +5V R3 32.4 k R4 17.8 k FIGURE 5-13: TC647B 3 V MIN CB 0.01 µF 2 C F CF 1.0 µF SENSE GND Q1 SI2302 or MGSF1N02E VOUT 7 5 CSENSE 0.1 µF RSENSE 3.0 4 Design Example Schematic. Bypass capacitor CVDD is added to the design to decouple the bias voltage.
PAGE 26
TC642B/TC647B 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 XXXXXX YWWNNN Legend: XX...
PAGE 27
TC642B/TC647B 8-Lead Plastic Dual In-line (P) – 300 mil (PDIP) Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.
PAGE 28
TC642B/TC647B 8-Lead Plastic Small Outline (SN) – Narrow, 150 mil (SOIC) Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.
PAGE 29
TC642B/TC647B 8-Lead Plastic Micro Small Outline Package (MS) (MSOP) Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 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 0.85 0.75 0.00 4.90 BSC 3.00 BSC 3.00 BSC 0.60 0.40 0.95 REF 0° 0.08 0.22 5° 5° - MIN Number of Pins 8 Pitch .026 BSC Overall Height A .043 A2 Molded Package Thickness .
PAGE 30
TC642B/TC647B 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 8-Pin MSOP Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size 12 mm 8 mm 2500 13 in.
PAGE 31
TC642B/TC647B 7.0 REVISION HISTORY Revision C (January 2013) Added a note to each package outline drawing.  2002-2013 Microchip Technology Inc.
PAGE 32
TC642B/TC647B DS21756C-page 32  2002-2013 Microchip Technology Inc.
PAGE 33
TC642B/TC647B 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 TC642B: PWM Fan Speed Controller with Minimum Fan Speed, Fan Restart, Fan Fault Detection, and Over-Temp Detection. TC647B: PWM Fan Speed Controller with Minimum Fan Speed, Fan Restart, and Fan Fault Detection.
PAGE 34
TC642B/TC647B NOTES: DS21756C-page 34  2002-2013 Microchip Technology Inc.
PAGE 35
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.
PAGE 36
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