Datasheet

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 2001-2012 Microchip Technology Inc. DS21448D-page 1

TC648

Features

• Temperature Proportional Fan Speed for Acoustic

Control and Longer Fan Life

• Efficient PWM Fan Drive

• 3.0V to 5.5V Supply Range:

- Fan Voltage Independent of TC648

Supply Voltage

- Supports any Fan Voltage

• Over-temperature Fault Detection

• Automatic Shutdown Mode for “Green” Systems

• Supports Low Cost NTC/PTC Thermistors

• Space Saving 8-Pin MSOP Package

Applications

• Power Supplies

• Computers

• Portable Computers

• Telecom Equipment

• UPSs, Power Amps

• General Purpose Fan Speed Control

Available Tools

• Fan Controller Demonstration Board (TC642DEMO)

• Fan Controller Evaluation Kit (TC642EV)

Package Types

General Description

The TC648 is a switch mode, fan speed controller for

use with brushless DC fans. Temperature proportional

speed control is accomplished using pulse width mod-

ulation (PWM). A thermistor (or other voltage output

temperature sensor) connected to the V

input

furnishes the required control voltage of 1.25V to 2.65V

(typical) for 0% to 100% PWM duty cycle. The TC648

can be configured to operate in either auto-shutdown or

minimum speed mode. In auto-shutdown mode, fan

operation is automatically suspended when measured

temperature (V

) is lower than a user programmed

minimum setting (V

). The fan is automatically

restarted, and proportional speed control restored,

when V

exceeds V

(plus hysteresis). Operation in

minimum speed mode is similar to auto-shutdown

mode, with the exception that the fan is operated at a

user programmed minimum setting when the mea-

sured temperature is low. An integrated Start-up Timer

ensures reliable motor start-up at turn-on, and when

coming out of shutdown or auto-shutdown mode.

The over-temperature fault output (OTF

) is asserted

when the PWM reaches 100% duty cycle, indicating a

possible thermal runaway situation.

The TC648 is available in the 8-pin plastic DIP, SOIC

and MSOP packages and is available in the industrial

and extended commercial temperature ranges.

TC648

GND

OTF

OUT

SOIC/PDIP/MSOP

Fan Speed Controller with Auto-Shutdown

and Over-Temperature Alert

Summary of content (28 pages)

PAGE 1
TC648 Fan Speed Controller with Auto-Shutdown and Over-Temperature Alert Features • Temperature Proportional Fan Speed for Acoustic Control and Longer Fan Life • Efficient PWM Fan Drive • 3.0V to 5.
PAGE 2
TC648 Functional Block Diagram VIN + VOTF – – VDD OTF PWM + CF Control Logic VOUT Start-up Timer OTF Clock Generator – VAS + SHDN – + VSHDN GND DS21448D-page 2 TC648 NC  2001-2012 Microchip Technology Inc.
PAGE 3
TC648 1.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings* Supply Voltage ......................................................... 6V Input Voltage, Any Pin... (GND – 0.3V) to (VDD + 0.3V) *Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions above those indicated in the operation sections of the specifications is not implied.
PAGE 4
TC648 DC ELECTRICAL SPECIFICATIONS (CONTINUED) Electrical Characteristics: Unless otherwise specified, TMIN  TA  TMAX, VDD = 3.0V to 5.5V Symbol Parameter Min Typ Max Units Test Conditions Pulse Width Modulator FOSC PWM Frequency 26 30 34 Hz CF = 1.0 µF tSTARTUP Start-up Timer — 32/F — Sec CF = 1.0 µF Note 1: Ensured by design, not tested. DS21448D-page 4  2001-2012 Microchip Technology Inc.
PAGE 5
TC648 2.0 PIN DESCRIPTIONS The descriptions of the pins are listed in Table 2-1. TABLE 2-1: Pin No. PIN FUNCTION TABLE Symbol Description 2.3 Analog Input (VAS) An external resistor divider connected to the VAS input sets the auto-shutdown threshold. Auto-shutdown occurs when VIN  VAS. During shutdown, supply current falls to 25 µA (typical). The fan is automatically restarted when VIN  (VAS +VHAS) (see Section 5.0, “Typical Applications” for more details).
PAGE 6
TC648 3.0 DETAILED DESCRIPTION 3.5 3.1 PWM If the voltage on VIN becomes less than the voltage on VAS, the fan is automatically shut off (auto-shutdown mode). The TC648 exits auto-shutdown mode when the voltage on VIN becomes higher than the voltage on VAS by VHAS (the auto-shutdown hysteresis voltage (see Figure 3-1)). The Start-up Timer is triggered and normal operation is resumed upon exiting auto-shutdown mode. The VAS input should be grounded if autoshutdown mode is not used.
PAGE 7
TC648 TC646 Status Normal Operation Auto-Shutdown Mode Normal Operation ShutDown Normal Operation HI 2.6V VAS + VHAS VAS TEMP. 1.2V tRESET VIN VREL VSHDN LO GND Time FIGURE 3-1: 4.0 TC648 Nominal Operation. SYSTEM BEHAVIOR The flowcharts describing the TC648’s behavioral algorithms are shown in Figure 4-1. They can be summarized as follows: 4.1 Power-Up (1) Assuming the device is not being held in shutdown or auto-shutdown mode (VIN > VAS)..........
PAGE 8
TC648 Normal Operation Power-Up Power-on Reset OTF = 1 VOUT Duty Cycle Prop. to VIN Yes Minimum Speed Mode VAS ≈ 0V Yes No VIN > VOTF? No Yes VIN < VAS? OTF = 0 AutoShutdown VOUT = 0 OTF = 1 No No VIN > (VAS + VHAS) Yes VIN < VAS ? YES AutoShutdown VOUT = 0 Fire Start-up Timer No Normal Operation Minimum Speed Mode VOUT = 0 Yes VIN ≈ 0V ? No VIN > 1.25V No VIN > 1.
PAGE 9
TC648 5.0 TYPICAL APPLICATIONS analysis. At the very least, anyone contemplating a design using the TC648 should consult the documentation for both the TC642EV (DS21403) and TC642DEMO (DS21401). Figure 5-1 shows the base schematic for the TC642DEMO. Designing with the TC648 involves the following: (1) The temperature sensor network must be configured to deliver 1.25V to 2.65V on VIN for 0% to 100% of the temperature range to be regulated.
PAGE 10
TC648 5.1 EQUATION Temperature Sensor Design VDD x R2 The temperature signal connected to VIN must output a voltage in the range of 1.25V to 2.65V (typical) for 0% to 100% of the temperature range of interest. The circuit in Figure 5-2 illustrates a convenient way to provide this signal using a temperature dependent voltage divider circuit.
PAGE 11
TC648 thermistor resistance at TMIN. R2 is then calculated to deliver the desired speed at TMIN. The values for R1, R2 and RT1 are then checked at TMAX for 2.65V nominal. It may be necessary to adjust the values of R1 and R2 after the initial calculation to obtain the desired results. The design equations are: 5.3 EQUATION As with the VIN input, 1.25V to 2.65V corresponds to the temperature range of interest from T1 to T2, respectively.
PAGE 12
TC648 Per Section 1.0, “Electrical Characteristics”, the leakage current at the VAS pin is no more than 1 µA. It is conservative to design for a divider current, IDIV, of 100 µA. If VDD = 5.0V then… EQUATION IDIV = 1e–4A 5.0V = R1 + R2 5.0V R1 + R2 = , therefore = 50,000 = 50 k 1e–4A We can further specify R1 and R2 by the condition that the divider voltage is equal to our desired VAS.
PAGE 13
TC648 VDD VDD VDD Fan Fan Fan RBASE RBASE VOUT VOUT Q1 Q1 Q1 VOUT Q2 GND GND GND a) Single Bipolar Transistor FIGURE 5-6: TABLE 5-1: Device MMBT2222A MPS2222A MPS6602 b) Darlington Transistor Pair C) N-Channel MOSFET Output Drive Transistor Circuit Topologies. TRANSISTORS AND MOSFETS FOR Q1 (VDD = 5V) Package Max. VBE(sat)/VGS (V) Min. HFE VCEO/VDS (V) Fan Current (mA) Suggested RBASE () SOT-23 1.2 50 40 150 800 TO-92 1.2 50 40 150 800 TO-92 1.
PAGE 14
TC648 +5V VDD R2* 2.2 kΩ VOUT TC648 D1 12.0V Zener Fan Q 1* R 4* 10 kΩ GND -12V NOTE: *Value depends on the specific application and is shown for example only. FIGURE 5-7: 5.5 Powering the Fan from a -12V Supply. Latch-up Considerations Auto-Shutdown Mode Design Example As with any CMOS IC, the potential exists for latch-up if signals are applied to the device which are outside the power supply range.
PAGE 15
TC648 +5V RESET Shutdown Open-Drain Device (Optional) NTC 10 kΩ @ 25˚C 1 R1 20.5 kΩ R2 3.83 kΩ CB 0.01 μF CB 1 μF VIN +12V +5V 8 VDD 4 Fan GND OTF 6 TC648 3 VAS CB 0.01 μF 2 R6 CF 18 kΩ CB 1 μF FIGURE 5-8: 5.8 Q1 R7 800Ω +5V R5 33 kΩ Thermal Fault VOUT NC 7 5 Design Example. TC648 as a Microcontroller Peripheral In a system containing a microcontroller or other host intelligence, the TC648 can be effectively managed as a CPU peripheral.
PAGE 16
TC648 +12V +5V (RESET)(Optional) Open-Drain I/O0 Outputs R1 110 kΩ I/O1 (MSB) Analog or Digital Temperature Data from one or more Sensors CMOS Outputs R2 240 kΩ I/O2 I/O3 +5V 1 V IN (LSB) R5 1.5 kΩ +5V .01 μF + R7 R4 33 kΩ 18 kΩ +5V R 8 18 kΩ R6 1 kΩ GND FIGURE 5-9: DS21448D-page 16 + CB 1 μFR CB R3 360 kΩ CMOS Microcontroller VDD 2 C F 3 CB VOUT 7 TC648 1 μF VAS OTF Fan 8 6 9 800Ω 2N2222A +5V R10 10 kΩ .01 μF 4 NC 5 GND INT TC648 as a Microcontroller Peripheral.
PAGE 17
TC648 6.0 PACKAGING INFORMATION 6.1 Package Marking Information 8-Lead PDIP (300 mil) XXXXXXXX NNN YYWW 8-Lead SOIC (150 mil) XXXXXXXX YYWW NNN 8-Lead MSOP e3 * Note: TC648VPA 025 0215 Example: TC648VOA 0215 025 Example: TC648E 215025 XXXXXX YWWNNN Legend: XX...
PAGE 18
TC648 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 19
TC648 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 20
TC648 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 p E1 D 2 B n 1  A2 A c  A1 (F) L  Number of Pins Pitch Overall Height MILLIMETERS* INCHES Units Dimension Limits n p MAX NOM MIN MIN NOM 0.65 .026 .044 A 1.18 .038 0.76 .006 0.05 .193 .200 .114 .118 .114 .118 L .016 .035 Foot Angle F  Lead Thickness c .
PAGE 21
TC648 6.
PAGE 22
TC648 7.0 REVISION HISTORY Revision D (December 2012) Added a note to each package outline drawing. DS21448D-page 22  2001-2012 Microchip Technology Inc.
PAGE 23
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PAGE 24
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PAGE 25
TC648 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 X /XX Temperature Range Package Device: TC648: Temperature Range: V E Package: PA = Plastic DIP (300 mil Body), 8-lead OA = Plastic SOIC, (150 mil Body), 8-lead UA = Plastic Micro Small Outline (MSOP), 8-lead Examples: a) TC648VOA: PWM Fan Speed Controller w/Auto Shutdown and Over-Temperature Alert, SOIC package.
PAGE 26
TC648 NOTES: DS21448D-page 26  2001-2012 Microchip Technology Inc.
PAGE 27
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 28
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