TC670ECHTR Microchip

TC670 Tiny Predictive Fan Failure Detector Features General Description Fan Wear-Out Detection for 2-Wire The TC670 is an integrated fan speed sensor that Linear-Controlled Fans predicts and/or detects fan failure, preventing thermal damage to systems with cooling fans. When the fan Replacement System for 3-Wire Fans speed falls below a user-specified level, the TC670 Fan Alert Signal when Fan Speed is below asserts an ALERT signal. With this design, a critical Programmed Threshold minimum fan speed is determined by the user. The fan CLEAR Capability for Eliminating False Alarm alert level is then set with a resistor divider on the Low Operating Current, 90 A (typ.) THRESHOLD pin (Pin 1) of the TC670. When the V Range 3.0V to 5.5V minimum fan speed is reached, the ALERT pin (Pin 5) DD changes from a digital high to low. This failure detection Available in a 6-Pin SOT-23 Package works with all linear-controlled 2-wire fans. The TC670 Applications eliminates the need for 3-wire fan solutions. A CLEAR option can be used to reset the ALERT sig- Protection for Linear-Controlled Fans nal, allowing the flexibility of connecting the ALERT Power Supplies output of the TC670 with other ALERT/FAULT inter- Industrial Equipment rupts in the system. This feature can be implemented PCs and Notebooks so that false fan fault conditions do not initiate system Data Storage shutdown. Data Communications Equipment The TC670 is specified to operate over the full Instrumentation industrial temperature range of -40C to +85C. The TC670 is offered in a 6-pin SOT-23 pin package and Package Type consumes 90 A (typ.) during operation. The space- saving package and low power consumption make this SOT-23A-6 device an ideal choice for systems requiring fan speed monitoring. THRESHOLD 1 6 SENSE Typical Application Circuit +5V GND25 ALERT CLEAR V 3 4 DD ALERT LED 4 V DD 0.1 F R 4 CLEAR +12V 3 5 ALERT From R 3 Microcontroller DCDC FAN 1 FAN C THRESHOLD SENSE 6 SENSE R 2 R SENSE GND 2 2001-2012 Microchip Technology Inc. DS21688D-page 1 TC670TC670 TABLE 1-1: PIN FUNCTION TABLE 1.0 ELECTRICAL CHARACTERISTICS Symbol Description THRESHOLD Analog Input Absolute Maximum Ratings GND Ground Terminal V ...................................................................................6.0V DD CLEAR Digital Input All Inputs and Outputs...........(GND 0.3V) to (V + 0.3V) DD VDD Bias Supply Input Output Short-Circuit Current .................................continuous ALERT Digital (Open-Drain) Output Current at Input Pin ................................................... +/-2 mA SENSE Analog Input Current at Output Pin .............................................. +/-25 mA Junction Temperature, T .............................................150C J ESD protection on all pins 4kV Operating Temperature Range........................-40C to +85C Storage Temperature Range.........................-55C to +150C Notice: Stresses above those listed underMaximum Rating 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 operation listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. DC CHARACTERISTICS Electrical Specifications: Unless otherwise specified, all limits are specified at +25C, V = 3.0V to 5.5V, DD CLEAR = Low. Boldface type specifications apply for temperature range of -40C to +85C. Parameters Sym Min Typ Max Units Conditions Power Supply Supply Voltage V 3.0 5.5 V DD Supply Current I 90 150 A DD CLEAR Input Logic Input High Level V 0.8V V IH DD Logic Input Low Level V 0.2V V IL DD SENSE Input Input Level Threshold Voltage V 124 mV TH(SENSE) Input Resistance R 50 k SENSE THRESHOLD Input Input Voltage Minimum 0.0 V Input Voltage Maximum 2.4 V Input Resistance 100 M Programmed Fan Speed Alert Accuracy ALERT -10 +10 % V = 3.0V ACC DD (Note 1) ALERT Output Output Low Voltage V 0.3 VI = 2.5 mA LOW SINK Output Delay Time t 176 ms DELAY Temperature Ranges Specified Temperature Range T -40 +85 C A Operating Temperature Range T -40 +125 C A Thermal Package Resistances Thermal Resistance, 6L-SOT-23 230 C/W JA Note 1: The TC670 will operate properly over the entire power supply range of 3.0V to 5.5V. As V varies from DD 3.0V, accuracy will degrade based on the percentage of V , as shown in Section 2.0, Typical DD Performance Curves. DS21688D-page 2 2001-2012 Microchip Technology Inc.