TC74

M Tiny Serial Digital Thermal Sensor Features • Digital Temperature Sensing in SOT-23-5 or TO-220 Packages • Outputs Temperature as an 8-Bit Digital Word • Simple SMBus/I2C™ Serial Port Interface • Solid-State Temperature Sensing: - ±2°C (max.) Accuracy from +25°C to +85°C - ±3°C (max.) Accuracy from 0°C to +125°C • Supply Voltage of 2.7V to 5.5V • Low Power: - 200 µA (typ.) Operating Current - 5 µA (typ.) Standby Mode Current TC74 General Description The TC74 is a serially accessible, digital temperature sensor particularly suited for low cost and small formfactor applications. Temperature data is converted from the onboard thermal sensing element and made available as an 8-bit digital word. Communication with the TC74 is accomplished via a 2wire SMBus/I2C compatible serial port. This bus also can be used to implement multi-drop/multi-zone monitoring. The SHDN bit in the CONFIG register can be used to activate the low power Standby mode. Temperature resolution is 1°C. Conversion rate is a nominal 8 samples/sec. During normal operation, the quiescent current is 200 µA (typ). During standby operation, the quiescent current is 5 µA (typ). Small size, low installed cost and ease of use make the TC74 an ideal choice for implementing thermal management in a variety of systems. Applications • Thermal Protection for Hard Disk Drives and other PC Peripherals • PC Card Devices for Notebook Computers • Low Cost Thermostat Controls • Power Supplies • Thermistor Replacement Functional Block Diagram Package Types TO-220 SDA 5 TC74 12345 Internal Sensor (Diode) SDA Serial Port Interface SCLK SOT-23 SCLK 4 TC74 1 2 GND 3 VDD Temperature Register ∆Σ Modulator Control Logic  2002 Microchip Technology Inc. NC SDA GND SCLK VDD NC Note: The TO-220 tab is connected to pin 3 (GND) DS21462C-page 1 TC74 1.0 1.1 ELECTRICAL CHARACTERISTICS Absolute Maximum Ratings† Supply Voltage (VDD) ............................................ +6V Voltage On Any Pin ....... (GND – 0.3V) to (VDD + 0.3V) Current On Any Pin .......................................... ±50 mA Operating Temperature (TA) ........ -40°C ≤ TA ≤ +125°C Storage Temperature (TSTG) .............. -65°C to +150°C Junction Temperature (TJ)................................ +150°C † Notice: Stresses above those listed under "Maximum Ratings" 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: U nless otherwise noted, VDD = 3.3V for TC74AX-3.3VXX and VDD = 5.0V for TC74AX-5.0VXX, -40°C ≤ TA ≤ 125°C. Note 5 Parameters Power Supply Power-on Reset Threshold Supply Voltage Operating Current Standby Supply Current Temperature-to-Bits Converter Temperature Accuracy TERR -2.0 -3.0 — 4 0.8 x VDD — — — — -1.0 10 4.7 4.0 — — ±2.0 8 — — — — 5.0 0.1 — — — +2.0 +3.0 — — — 0.2 x V DD 0.4 0.6 — 1.0 100 — — °C +25°C