General description:

The PCT2075 is a temperature-to-digital converter featuring ±1 °C accuracy over -25 °Cto +100 °C range. It uses an on-chip band gap temperature sensor and Sigma-Delta Ato-D conversion technique with an overtemperature detection output that is a drop-inreplacement for other LM75 series thermal sensors. The device contains a number ofdata registers: Configuration register (Conf) to store the device settings such as deviceoperation mode, OS operation mode, OS polarity and OS fault queue; temperatureregister (Temp) to store the digital temp reading, set-point registers (Tos and Thyst) tostore programmable overtemperature shutdown and hysteresis limits, and programmabletemperature sensor sampling time Tidle, that can be communicated by a controller viathe 2-wire serial I2C-bus Fast-mode Plus interface.The PCT2075 also includes an open-drain output (OS) which becomes active when thetemperature exceeds the programmed limits. The OS output operates in either of twoselectable modes: OS comparator mode or OS interrupt mode. Its active state can beselected as either HIGH or LOW. The fault queue that defines the number of consecutivefaults in order to activate the OS output is programmable as well as the set-point limits.The PCT2075 can be configured for different operation conditions. It can be set in normalmode to periodically monitor the ambient temperature, or in shut-down mode to minimizepower consumption.The temperature register always stores an 11-bit two’s complement data, giving atemperature resolution of 0.125 °C. This high temperature resolution is particularly usefulin applications of measuring precisely the thermal drift or runaway. When the deviceis accessed the conversion in process is not interrupted (that is, the I2C-bus sectionis totally independent of the Sigma-Delta converter section) and accessing the devicecontinuously without waiting at least one conversion time between communications willnot prevent the device from updating the Temp register with a new conversion result. Thenew conversion result is available immediately after the Temp register is updated. It isalso possible to read just one of the temperature register bytes without lock-up.The PCT2075 powers up in the normal operation mode with the OS in comparator mode,temperature threshold of 80 °C and hysteresis of 75 °C, so that it can be used as astand-alone thermostat with those pre-defined temperature set points. The default setpoints can be modified during manufacture and ordered under custom part number.There are three selectable logic address pins with three logic states so that 27 8-pindevices or three 6-pin devices can be connected on the same bus without addressconflict.

Features and benefits:

• Pin-for-pin replacement for LM75 series but allows up to 27 devices on the bus

• Power supply range from 2.7 V to 5.5 V

• SDA and SCL inputs are overvoltage tolerant to 5.5 V

• SDA and OS open drain outputs can be pulled up to 5.5 V regardless of supply voltage• Temperatures range from -55 °C to +125 °C

• Frequency range 20 kHz to 1 MHz with SMBus time-out to prevent hanging up the bus

• 1 MHz Fast-mode Plus 30 mA SDA drive allows more devices on the same bus but isbackward compatible to Fast-mode and Standard-mode

• 11-bit ADC that offers a temperature resolution of 0.125 °C

• Temperature accuracy of:– ±1 °C (max.) from -25 °C to +100 °C– ±2 °C (max.) from -55 °C to +125 °C

• Programmable temperature threshold and hysteresis set points during operation

• Supply current of <1.0 μA in shut-down mode for power conservation

• Stand-alone operation as thermostat at power-up

• ESD protection exceeds 2000 V HBM per JESD22-A114 and 1000 V CDM perJESD22-C101

• Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

• Small 8-pin package types: SO8, TSSOP8 and 2 mm × 3 mm HWSON8

• Small 6-pin package type: TSOP6

Applications:

• System thermal management

• Personal computers

• Electronics equipment

• Industrial controllers

• Cooling system: turn on when the temperature is higher (hotter) than -5 °C; turn offwhen the temperature is below -10 °C