PCT2075GVX

PCT2075 I2C-bus Fm+, 1 C accuracy, digital temperature sensor and thermal watchdog Rev. 10 — 20 November 2017 Product data sheet 1. General description The PCT2075 is a temperature-to-digital converter featuring 1 C accuracy over 25 C to +100 C range. It uses an on-chip band gap temperature sensor and Sigma-Delta A-to-D conversion technique with an overtemperature detection output that is a drop-in replacement for other LM75 series thermal sensors. The device contains a number of data registers: Configuration register (Conf) to store the device settings such as device operation mode, OS operation mode, OS polarity and OS fault queue; temperature register (Temp) to store the digital temp reading, set-point registers (Tos and Thyst) to store programmable overtemperature shutdown and hysteresis limits, and programmable temperature sensor sampling time Tidle, that can be communicated by a controller via the 2-wire serial I2C-bus Fast-mode Plus interface. The PCT2075 also includes an open-drain output (OS) which becomes active when the temperature exceeds the programmed limits. The OS output operates in either of two selectable modes: OS comparator mode or OS interrupt mode. Its active state can be selected as either HIGH or LOW. The fault queue that defines the number of consecutive faults 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 normal mode to periodically monitor the ambient temperature, or in shut-down mode to minimize power consumption. The temperature register always stores an 11-bit two’s complement data, giving a temperature resolution of 0.125 C. This high temperature resolution is particularly useful in applications of measuring precisely the thermal drift or runaway. When the device is accessed the conversion in process is not interrupted (that is, the I2C-bus section is totally independent of the Sigma-Delta converter section) and accessing the device continuously without waiting at least one conversion time between communications will not prevent the device from updating the Temp register with a new conversion result. The new conversion result is available immediately after the Temp register is updated. It is also 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 a stand-alone thermostat with those pre-defined temperature set points. The default set points 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-pin devices or three 6-pin devices can be connected on the same bus without address conflict. PCT2075 NXP Semiconductors I2C-bus Fm+ digital temperature sensor and thermal watchdog 2. 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 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 is backward 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 Thys. Otherwise, the OS output state is undefined. PCT2075 Product data sheet All information provided in this document is subject to legal disclaimers. Rev. 10 — 20 November 2017 © NXP Semiconductors N.V. 2017. All rights reserved. 14 of 37 PCT2075 NXP Semiconductors I2C-bus Fm+ digital temperature sensor and thermal watchdog 7.7 OS fault queue Fault queue is defined as the number of faults that must occur consecutively to activate the OS output. It is provided to avoid false tripping due to noise. Because faults are determined at the end of data conversions, fault queue is also defined as the number of consecutive conversions returning a temperature trip. The value of fault queue is selectable by programming the two bits B4 and B3 (OS_F_QUE[1:0]) in register Conf. Notice that the programmed data and the fault queue value are not the same. Table 17 shows the one-to-one relationship between them. At power-up, fault queue data = 0 and fault queue value = 1. Table 17. Fault queue table Fault queue data Fault queue value OS_F_QUE[1] OS_F_QUE[0] Decimal 0 0 1 0 1 2 1 0 4 1 1 6 7.8 Shutdown mode The device operation mode is selected by programming bit B0 (SHUTDOWN) of register Conf. Setting bit SHUTDOWN to logic 1 puts the device into shutdown mode. Resetting bit SHUTDOWN to logic 0 returns the device to normal mode. In shutdown mode, the PCT2075 draws a small current of