TC74 M Tiny Serial Digital Thermal Sensor Features General Description Digital Temperature Sensing in SOT-23-5 or The TC74 is a serially accessible, digital temperature TO-220 Packages sensor particularly suited for low cost and small form- factor applications. Temperature data is converted from Outputs Temperature as an 8-Bit Digital Word 2 the onboard thermal sensing element and made Simple SMBus/I C Serial Port Interface available as an 8-bit digital word. Solid-State Temperature Sensing: Communication with the TC74 is accomplished via a 2- - 2C (max.) Accuracy from +25C to +85C 2 wire SMBus/I C compatible serial port. This bus also - 3C (max.) Accuracy from 0C to +125C can be used to implement multi-drop/multi-zone Supply Voltage of 2.7V to 5.5V monitoring. The SHDN bit in the CONFIG register can Low Power: be used to activate the low power Standby mode. - 200 A (typ.) Operating Current Temperature resolution is 1C. Conversion rate is a - 5 A (typ.) Standby Mode Current nominal 8 samples/sec. During normal operation, the quiescent current is 200A (typ). During standby Applications operation, the quiescent current is 5 A (typ). Thermal Protection for Hard Disk Drives Small size, low installed cost and ease of use make the TC74 an ideal choice for implementing thermal and other PC Peripherals management in a variety of systems. PC Card Devices for Notebook Computers Low Cost Thermostat Controls Functional Block Diagram Power Supplies Thermistor Replacement Internal Sensor Package Types SDA (Diode) Serial Port Interface TO-220 SOT-23 SCLK SDA SCLK Modulator 5 4 TC74 Control Logic TC74 12 3 4 5 12 3 Temperature NC GND V DD Register Note: The TO-220 tab is connected to pin 3 (GND) 2002 Microchip Technology Inc. DS21462C-page 1 NC SDA GND SCLK VDDTC74 Notice: Stresses above those listed underMaxi- 1.0 ELECTRICAL mum Rating may cause permanent damage to the CHARACTERISTICS device. This is a stress rating only and functional oper- ation of the device at those or any other conditions 1.1 Absolute Maximum Ratings above those indicated in the operation listings of this specification is not implied. Exposure to maximum rat- Supply Voltage (V ) ............................................ +6V DD ing conditions for extended periods may affect device Voltage On Any Pin .......(GND 0.3V) to (V + 0.3V) DD reliability. Current On Any Pin ..........................................50 mA Operating Temperature (T ) ........ -40C T +125C A A Storage Temperature (T )..............-65C to +150C STG Junction Temperature (T )................................ +150C J DC CHARACTERISTICS Electrical Specifications: Unless otherwise noted, V = 3.3V for TC74AX-3.3VXX and DD V = 5.0V for TC74AX-5.0VXX, -40C T 125C. Note 5 DD A Parameters Sym Min Typ Max Units Conditions Power Supply Power-on Reset Threshold V 1.2 2.2 V V Falling Edge or Rising POR DD Edge Supply Voltage V 2.7 5.5 V Note 5 DD Operating Current I 200 350 A V = 5.5V, Note 1 DD DD Standby Supply Current I 5.0 10 A V = 3.3V DD-STANDBY DD Serial Port Inactive, Note 4 Temperature-to-Bits Converter Temperature Accuracy T -2.0 +2.0 C +25C <T < +85C ERR A -3.0 +3.0 0C < T < +125C A 2.0 -40C < T < 0C A Conversion Rate CR 4 8 SPS Note 2 Serial Port Interface Logic Input High V 0.8 x V V IH DD Logic Input Low V 0.2 x V V IL DD SDA Output Low V 0.4 V I = 3 mA OL OL 0.6 V I = 6 mA, Note 3 OL Input Capacitance SDA, SCLK C 5.0 pF IN -1.0 0.1 1.0 A I/O Leakage I LEAK Serial Port AC Timing (C = 80 pF) LOAD 2 SMBus/I C Clock Frequency f 10 100 kHz SMB 4.7 sec 10% to 10% Low Clock Period t LOW High Clock Period t 4.0 sec 90% to 90% HIGH Note 1: Operating current is an average value integrated over multiple conversion cycles. Transient current may exceed this specification. 2: Maximum ensured conversion time after Power-on Reset (POR to DATA RDY) is 250 msec. 3: Output current should be minimized for best temperature accuracy. Power dissipation within the TC74 will cause self-heating and temperature drift error. 4: SDA and SCLK must be connected to V or GND. DD 5: V = 3.3V for TC74AX -3.3 VXX. V = 5.0V for TC74AX -5.0 VXX. All part types of the TC74 will operate DD DD properly over the wider power supply range of 2.7V to 5.5V. Each part type is tested and specified for rated accuracy at its nominal supply voltage. As V varies from the nominal value, accuracy will degrade 1C/V DD of V change. DD DS21462C-page 2 2002 Microchip Technology Inc.