1. General description
The SE95 is a temperature-to-digital converter using an on-chip band gap temperature
sensor and Sigma Delta analog-to-digital conversion technique. The device is also a
thermal detector providing an overtemperature detection output.
The SE95 contains a number of data registers accessed by a controller via the 2-wire
serial I
2
C-bus interface:
• Configuration register (Conf) to store the device settings such as sampling rate,
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
• Identification register (ID) to store manufacturer numbers
The device includes an open-drain output (pin OS) which becomes active when the
temperature exceeds the programmed limits. There are three selectable logic address
pins (pins A2 to A0) so that eight devices can be connected on the same bus without
address conflict.
The SE95 can be configured for different operation conditions. It can be set in normal
mode to periodically monitor the ambient temperature, or in shutdown mode to minimize
power consumption. The OS output operates in either of two selectable modes: OS
comparator mode and 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 temperature register always stores a 13-bit two’s complement data giving a
temperature resolution of 0.03125 °C. This high temperature resolution is particularly
useful in applications of measuring precisely the thermal drift or runaway. For normal
operation and compatibility with the LM75A, only the 11 MSBs are read, with a resolution
of 0.125 °C to provide the accuracies specified. To be compatible with the LM75, read only
the 9 MSBs.
The device is powered-up in 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 conversion
rate is programmable, with a default of 10 conversions/s.
SE95
Ultra high accuracy digital temperature sensor and thermal
watchdog
Rev. 07 — 2 September 2009 Product data sheet
