DS1676

The DS1676 is an integrated elapsed time recorder that will provide the total amount of time that an event is/has been active since the DS1676 was last reset to zero via the 2-wire bus. This is ideal for applications such as  onitoring the total amount of time that something is turned on or in operation, how long something has been used, or the total number of uses since the last calibration or repair.

The DS1676 uses a calibrated, temperature compensated, RC time base to increment an elapsed time counter while an event is active. When the event becomes active, the contents of the non-volatile Total Time Accumulator register are downloaded to the Elapsed Time Counter (ETC) and as the event continues, the ETC is incremented in quarter second increments. When the event becomes inactive or the power is removed, the DS1676 will increment the 17-bit non-volatile Event Counter register and put the contents of the ETC into the 32-bit non-volatile Total Accumulated Time register which can hold up to 34 years of active event time. A storage cap may be required on VCC to provide enough power to store the value in the ETC to the Total Time Accumulator register if power is taken away at the same time the event ends.

There is no way for this device DS1676 to be reset if the Reset Enable pin is held low. With the Reset Enable pin high, the DS1676 can be reset by the Reset command sent over the 2-wire bus. If a switch or button is used to control the polarity of the Reset Enable pin, a debounce capacitor should be used to prevent spikes on the input.

The Write Memory Disable DS1676 is used to control the writability of the 10 bytes of EEPROM User memory. The Write Memory Disable Flag is set to a 1 when the Write Memory Disable command is written twice and can not be changed once it is set to a 1. If the Write Memory Disable flag is set to a 1, the 10 bytes of memory will not be able to be written or erased. If the Write Memory Disable flag is a 0, the user will have full access to the bytes with the standard EEPROM write time restrictions.

When data is written to the device DS1676, the device slave address will be sent first followed by the address pointer and the desired byte of data. Once a single byte of data is sent, there must be at least a 20 mS to allow the EEPROM to update the data.