Rainbow Electronics DS1629 - Manual (Page 3)

DS1629
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The crystal frequency is internally divided by a factor that the user defines. The divided output is buffered
and can be used to clock a microcontroller.
The DS1629 features an open-drain alarm output. It can be configured to activate on a thermal event, time
event, either thermal or time, or neither thermal nor time (disabled, power-up state). The thermal alarm
becomes active when measured temperature is greater than or equal to the value stored in the TH
thermostat register. It will remain active until temperature is equal to or less than the value stored in TL,
allowing for programmable hysteresis. The clock alarm will activate at the specific minute of the week
that is programmed in the clock alarm register. The time alarm is cleared by reading from or writing to
either the clock register or the clock alarm register.
The DS1629 configuration register defines several key items of device functionality. It sets the
conversion mode of the digital thermometer and what event, if any, will constitute an alarm condition. It
also sets the active state of the alarm output. Finally, it enables/disables and sets the division factor for the
oscillator output.
The DS1629 also features 32 bytes of SRAM for storage of general information. This memory space has
no bearing on thermometer or chronograph operation. Possible uses for this memory are
time/temperature histogram storage, thermal datalogging, etc.
Digital data is written to/read from the DS1629 via a 2-wire interface, and all communication is MSb
first. Individual registers are accessed by unique 8-bit command protocols.
The DS1629 features a wide power supply range (2.2V
≤
V
DD
≤
5.5V) for clock functionality, SRAM
data retention, and 2-wire communication. EEPROM writes and temperature conversions should only be
performed at 2.7V
≤
V
DD
≤
5.5V for reliable results.