Monthly Archives: March 2017

Ultra high accuracy digital temperature sensor and thermal watchdog

Providing an overtemperature detection output, the SE95 is a temperature-to-digital converter using an on-chip band gap temperature sensor and Sigma Delta analog-to-digital conversion technique. Aside from being a converter, SE95 also functions as a thermal detector. It contains a number of data registers accessed by a controller via the 2-wire serial I²C-bus interface.

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 device is powered-up in normal operation mode with the OS in comparator mode, temperature threshold of 80 Cel and hysteresis of 75 Cel, so that it can be used as a stand-alone thermostat with those pre-defined temperature set points.

BLOCK DIAGRAM: SE95D, SE95DP, SE95U

BLOCK DIAGRAM: SE95D, SE95DP, SE95U

Why Used

  • Pin-for-pin replacement for industry standard LM75/LM75A
  • 13-bit ADC that offers a temperature resolution of 0.03125 Cel
  • Programmable temperature threshold and hysteresis set points
  • Stand-alone operation as thermostat at power-up
  • Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

Where Used

  • System thermal management
  • Personal computers
  • Electronics equipment
  • Industrial controllers

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DDR memory module temp sensor, 1.7 V to 3.6 V

Mounted on a Dual In-Line Memory Module (DIMM), the NXP Semiconductors SE98A measures temperature from -40 ºC and +125 ºC with JEDEC Grade B ±1 ºC accuracy between +75 ºC and +95 ºC communicating via the I2C-bus/SMBus. The SE98A thermal sensor operates over the VDD range of 1.7 V to 3.6 V. The SE98A does not include the 2 k SPD and is designed for custom DIMM where larger SPD is required.

The SE98A supports the industry-standard 2-wire I²C-bus/SMBus serial interface. The SMBus TIMEOUT function is supported to prevent system lock-ups. Manufacturer and Device ID registers provide the ability to confirm the identify of the device. Three address pins allow up to eight devices to be controlled on a single bus. The SE98A supports the industry-standard 2-wire I²C-bus/SMBus serial interface. The SMBus TIMEOUT function is supported to prevent system lock-ups. Manufacturer and Device ID registers provide the ability to confirm the identify of the device. Three address pins allow up to eight devices to be controlled on a single bus.

Block diagram: SE98APW, SE98ATL, SE98ATP

Block diagram: SE98APW, SE98ATL, SE98ATP

Why Used

  • SMBus ALERT and TIMEOUT (programmable)
  • 11-bit ADC Temperature-to-Digital converter with 0.125 ºC resolution
  • Programmable hysteresis threshold: 0 ºC, 1.5 ºC, 3 ºC, 6 ºC
  • Over/under/critical temperature EVENT output
  • Latch-up testing is done to JEDEC Standard JESD78 which exceeds 100 mA

Where Used

  • DDR2 and DDR3 memory modules
  • Laptops, personal computers and servers
  • Enterprise networking
  • hard disk drives and other PC peripherals

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