TC650BEVUATR

TC650/TC651 Tiny Integrated Temperature Sensor & Brushless DC Fan Controller with Overtemperature Alert Features General Description • Integrated Temperature Sensing and Multi-speed Fan Control • Built-in Overtemperature Alert (TOVER) • Temperature-proportional Fan Speed Control for Acoustic Noise Reduction and Longer Fan Life • Pulse Width Modulation (PWM) Output Drive for Cost and Power Savings • Solid-state Temperature Sensing • ±1C (typ.) Accuracy from 25C to +70C • Operating Range: 2.8V – 5.5V • TC651 includes Automatic Fan Shutdown • Low Operating Current: 50 µA (typ.) The TC650/TC651 are integrated temperature sensors and brushless DC fan speed controllers. The TC650/ TC651 measure the junction temperature and control the speed of the fan based on that temperature, making them especially suited for applications in modern electronic equipment. Applications • • • • • • Thermal Protection For Personal Computers Digital Set-Top Boxes Notebook Computers Data Communications Power Supplies Projectors Related Literature • Application Note 771 (DS00771) Temperature data is converted from the on-chip thermal sensing element and translated into a fractional fan speed from 40% to 100%. A temperature selection guide in the data sheet is used to choose the low and high temperature limits to control the fan. The TC650/TC651 also include a single trip point overtemperature alert (TOVER) that eliminates the need for additional temperature sensors. In addition, the TC651 features an auto fan shutdown function for additional power savings. The TC650/TC651 are easy to use, require no software overhead and are, therefore, the ideal choice for implementing thermal management in a variety of systems. Package Type 8-Pin MSOP VDD 1 NC 2 SHDN 3 GND 4  2001-2012 Microchip Technology Inc. 8 PWM TC650 TC651 7 GND 6 TOVER 5 NC DS21450D-page 1 TC650/TC651 Typical Application Circuit +12V PIC® Microcontroller +5V VDD SHDN Control DC Fan 500 mA TC650 TC651 1 VDD PWM 8 2 NC GND 7 3 SHDN 4 GND CSLOW TOVER 6 NC 5 GND GND Overtemperature Alert DS21450D-page 2  2001-2012 Microchip Technology Inc. TC650/TC651 1.0 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings† Input Voltage (VDD to GND) ................................... +6V † Notice: 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. Exposure to Absolute Maximum Rating conditions for extended periods may affect device reliability. Output Voltage (OUT to GND) ................................. 6V Voltage On Any Pin ....... (GND – 0.3V) to (VDD + 0.3V) Operating Temperature Range ......... –40C to +125C Storage Temperature ........................ –65C to +150C DC CHARACTERISTICS Electrical Specifications: Unless otherwise specified, VDD = 2.8V to 5.5V, SHDN = VDD, TA = –40C to +125C. Parameters Sym Min Typ Max Units Conditions Supply Voltage VDD 2.8 — 5.5 V Supply Current IDD — 50 90 µA SHDN Input High Threshold VIH 65 — — %VDD SHDN Input Low Threshold VIL — — 15 %VDD PWM Output Low Voltage VOL — — 0.3 V ISINK = 1 mA PWM Output High Voltage VOH VDD – 0.5 — — V ISOURCE = 5 mA PWM Rise Time tR — 10 — µs IOH = 5 mA, 1 nF from PWM to GND PWM Fall Time tF — 10 — µs IOL = 1 mA, 1 nF from PWM to GND fOUT 10 15 — Hz tSTARTUP — 32/fOUT — sec PWM, TOVER are open SHDN Input PWM Output PWM Frequency Start-up Time VDD Rises from GND or SHDN Released Temperature Accuracy High Temperature Accuracy TH ACC TH – 3 TH TH + 3 °C Note 1 –1.0 — +1.0 °C (TH – TL)  20C –2.5 — +2.5 °C (TH – TL)  20C THYST — (TH -TL)/5 — °C TC651 Only TOVER Output High Voltage VHIGH VDD – 0.5 — — V ISOURCE = 1.2 mA TOVER Output Low Voltage VLOW — — 0.4 V ISINK = 2.5 mA Absolute Accuracy TOVER ACC — TH + 10 — °C At Trip Point Trip Point Hysteresis TOVER HYST — 5 — °C Temperature Range Accuracy (TH –TL) ACC Auto-shutdown Hysteresis TOVER Output Note 1: Transition from 90% to 100% Duty Cycle.  2001-2012 Microchip Technology Inc. DS21450D-page 3 TC650/TC651 TEMPERATURE CHARACTERISTICS Electrical Specifications: Unless otherwise noted, VDD = 2.8V to 5.5V, SHDN = VDD, TA = -40C to +125C. Parameters Sym Min Typ Max Units Specified Temperature Range TA –40 — +125 °C Maximum Junction Temperature TJ — — +150 °C Storage Temperature Range TA –65 — +150 °C JA — 206.3 — °C/W Conditions Temperature Ranges Package Thermal Resistances Thermal Resistance, 8L-MSOP DS21450D-page 4  2001-2012 Microchip Technology Inc. TC650/TC651 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 = 2.8V to 5.5V, SHDN = VDD, TA = –40C to +125C. 90 3.0 80 2.5 VDD = 5.6 60 IDD (µA) Temp Accuracy (°C) 70 50 40 VDD = 2.7 30 20 2.0 1.5 1.0 VDD = 5.6 0.5 10 0.0 0 -50 -25 0 50 25 75 100 125 150 VDD = 2.7 T1 TL T2 FIGURE 2-1: IDD vs. Temperature. FIGURE 2-4: VTH. 500 1.0 450 0.9 400 VDD - VOH (V) VOL (mV) 300 VDD = 5.5V 250 200 150 100 50 0.0 T4 TH Temperature Accuracy vs. 0.8 VDD = 2.8V 350 T3 TTHRESHOLD TEMPERATURE (°C) 0.7 VDD = 2.8V 0.6 VDD = 5.5V 0.5 0.4 0.3 0.2 TA = +25°C 0 1 2 3 4 5 6 7 8 9 10 0.1 0.0 ISINK (mA) FIGURE 2-2: PWM, ISINK vs. VOL. FIGURE 2-5: (VDD – VOH). TA = +25°C 0 2 4 6 8 10 12 14 16 18 20 ISOURCE (mA) PWM, ISOURCE vs. 1.0 0.9 VDD = 2.8V VDD - VOH (V) 0.8 0.7 0.6 VDD = 5.5V 0.5 0.4 0.3 0.2 TA = +25°C 0.1 0.0 0 1 2 3 4 5 6 7 8 9 10 ISOURCE (mA) FIGURE 2-3: (VDD – VOH). TOVER, ISOURCE vs.  2001-2012 Microchip Technology Inc. DS21450D-page 5 TC650/TC651 3.0 PIN DESCRIPTION The descriptions of the pins are listed in Table 3-1. TABLE 3-1: PIN FUNCTION TABLE Pin No. Symbol 1 VDD Power Supply Input 2 NC No Internal Connect 3 SHDN 4 GND 5 NC 6 TOVER 7 GND Ground 8 PWM PWM Fan Drive Output 3.1 Description Fan Shutdown, Active-low Input 1 = Fan in normal operation 0 = Fan in shutdown Ground No Connect Overtemperature Alert, Active-low Output 1 = Overtemperature condition does not exist 0 = The device is in the overtemperature condition. The fan is driven at 100%. Potential exists for system over-heating Power Supply Input 3.4 Overtemperature Alert May be independent of fan power supply. Active-low output. 3.2 3.5 Fan Shutdown, Active-low Input During Shutdown mode, the chip still monitors temperature. TOVER is low if temperature rises above factory set point. 3.3 PWM Fan Drive Output Pulse width modulated rail-to-rail logic output. Nominal frequency is 15 Hz. Ground Ground return for all TC650/TC651 functions. DS21450D-page 6  2001-2012 Microchip Technology Inc. TC650/TC651 4.0 DETAILED DESCRIPTION 4.2 The TC650/TC651 acquire and convert their junction temperature (TJ) information from an on-chip, solidstate sensor with a typical accuracy of ±1°C. The temperature data is digitally stored in an internal register. The register is compared with pre-defined threshold values. The six threshold values are equally distributed over a pre-defined range of temperatures (see Table 41). The TC650/TC651 control the speed of a DC brushless fan using a fractional speed-control scheme. The output stage requires only a 2N2222-type, small-signal BJT for fans up to 300 mA. For larger current fans (up to 1 amp), a logic-level N-channel MOSFET may be used. In addition to controlling the speed of the fan, the TC650/TC651 include an on-chip overtemperature alarm (TOVER) that gives a low signal when the temperature of the chip exceeds TH by 10°C (typical). This feature eliminates the need for a separate temperature sensor for overtemperature monitoring. Figure 4-1 shows the block diagram of the device. TOVER VDD Temperature Set Point and Trim Range V+ SHDN Duty Cycle Logic Control PWM A/D Converter Oscillator Temperature Sensor FIGURE 4-1: 4.1 Functional Block Diagram. PWM Output The PWM pin is designed to drive a low-cost transistor or MOSFET as the low-side, power-switching element in the system. This output has an asymmetric complementary drive and is optimized for driving NPN transistors or N-channel MOSFETs. Since the system relies on PWM rather than linear power control, the dissipation in the power switch is kept to a minimum. Generally, very small devices (TO-92 or SOT packages) will suffice. The frequency of the PWM is about 15 Hz. The PWM is also the time base for the Start-up Timer (see Section 4.2 “Start-Up Timer”). The PWM duty cycle has a range of 40% to 100% for the TC650 and 50% to 100% for the TC651.  2001-2012 Microchip Technology Inc. Start-Up Timer To ensure reliable fan start-up, the Start-up Timer turns PWM high for about 2 seconds whenever the fan is started from the off state. This occurs at power-up and when coming out of Shutdown mode. 4.3 Overtemperature Alert (TOVER) This pin goes low when the TH set point is exceeded by 10°C (typical). This indicates that the fan is at maximum drive and the potential exists for system overheating; either heat dissipation in the system has gone beyond the cooling system's design limits or some fault exists (such as fan bearing failure or an airflow obstruction). This output may be treated as a “System Overheat” warning and be used to either trigger system shutdown or bring other fans in the system to full speed. The fan will continue to run at full speed while TOVER is asserted. Built-in hysteresis prevents TOVER from “chattering” when the measured temperature is at or near the TH + 10°C trip point. As temperature falls through the TH + 10°C trip point, hysteresis maintains the TOVER output low until the measured temperature is 5°C above the trip point setting. 4.4 Shutdown (SHDN) The fan can be unconditionally shut down by pulling the SHDN pin low. During shutdown, the PWM output is low; ideal for notebook computers and other portable applications where you need to change batteries and must not have the fan running at that time. Thermal monitoring and TOVER are still in operation during shutdown. IDD shutdown current is around 50 µA. 4.5 Auto-shutdown Mode The TC651 features auto-shutdown. When the temperature is below the factory set point at minimum speed (TL), PWM is low and the fan is automatically shut off (Auto-shutdown mode). This feature is ideal for notebook computers and other portable equipment that need to conserve as much battery power as possible and, thus, run a fan when it is only absolutely needed. The TC651 will continue to be active in order to monitor temperature for TOVER. The TC651 exits Autoshutdown mode when the temperature rises above the factory set point (T1). DS21450D-page 7 TC650/TC651 4.6 Temperature Selection Guide (Minimum Fan Speed/Full Speed) There are two temperature thresholds that determine the characteristics of the device. The minimum fan speed temperature (TL) and the full fan speed temperature (TH). Depending on the TC65X device selected, when the temperature is below the TL trip point, the PWM output will perform a different operation. For the TC650, the PWM will be driven at the minimum PWM frequency, while the TC651 will shut down the PWM (PWM = L). TL and TH can be selected in 5°C increments. TL can range from 25°C to 35°C. TH can range from 35°C to 55°C and must be 10°C (or more) than the specified TL. The five temperature regions defined by the six thresholds are defined in the TC650/TC651 by means of factory trimming. Once a TL and TH are set, the T1 – T4 thresholds are automatically equally spaced between TL and TH. Table 4-1 shows these 5 regions and what the corresponding PWM duty cycle is. TABLE 4-1: TC650 (Minimum Speed mode) TC651 (Auto-shutdown mode) T < TL 40% Off TL< = T < T1 50% 50% T 1 < = T < T2 60% 60% T2 < = T