DS1616 Maxim Integrated Products, DS1616 Datasheet - Page 20

• Manufacturer Part Number: DS1616
• Description: Board Mount Temperature Sensors
• Manufacturer: Maxim Integrated Products

Specifications of DS1616

• Full Temp Accuracy: +/- 2 C
• Package / Case: PDIP-24
• Digital Output - Bus Interface: Serial (3-Wire)
• Digital Output - Number Of Bits: 8 bit
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Output Type: Digital

DS1616
STATUS 2 REGISTER
MSb
LSb
0
ALF1
AHF1
ALF2
AHF2
ALF3
AHF3
0
ALFx - ADC Data Low Flag [1-3] - A logic 1 in the ADC Data Low Flag [1-3] bits indicate that the
ADC Channel [1-3] Data from the corresponding channel is/has been less than or equal to the value in the
corresponding ADC Data Low Threshold [1-3] register. If ALIE is also a logic 1, the
pin will go
INT
low. ALFx is cleared by writing this bit to a logic 0. The Clear Memory command has no affect on this
bit.
AHFx - ADC Data High Flag [1-3] - A logic 1 in the ADC Data High Flag [1-3] bits indicate that the
corresponding ADC Channel [1-3] Data is/has been greater than or equal to the value in the
corresponding ADC Data High Threshold [1-3] register. If AHIE is also a logic 1, the
pin will go
INT
low. AHFx is cleared by writing this bit to a logic 0. The Clear Memory command has no effect on this
bit.
SILICON SERIAL NUMBER
A unique 64-bit lasered serial number is located in the register bank. This serial number is divided into
three parts. The first byte contains a model number to identify the device type (19h). The next six
registers contain a unique binary number. The last serial number byte contains a CRC byte used to
validate the data in the first seven serial number registers. All 8 bytes of the serial number are read-only
registers.
The DS1616 is manufactured such that no two devices will contain an identical serial number. Blocks of
numbers can be reserved by the customer.
Contact Dallas Semiconductor for special ordering
information for devices with reserved blocks of serial numbers.
SECURITY
The DS1616 provides several measures to insure data integrity for the end user. These security measures
are intended to prevent third party intermediaries from tampering with the data that has been stored in the
Datalog and Histogram memory.
As a first security measure, the Datalog and Histogram memory are read-only from the perspective of the
end user. The DS1616 can write sampled data into these memory banks, but the end user cannot write
data to individual registers. This prevents an unscrupulous intermediary from writing false data to the
DS1616. The end user, however, can clear the contents of the Datalog and Histogram memory. This is
accomplished by enabling and issuing the Clear Memory command.
A second security feature lies in the fact that once the sample rate has been selected by writing to the
Sample Rate register, it cannot be changed to another value without resetting the recorded data. This
prevents gathering many data samples at a fast sample rate and then lowering the sample rate to give the
appearance that the data was recorded over a longer period of time. The Sample Rate register can only be
written to a new value if the MEM CLR bit is set to 1.
A third security feature lies in the two integrated sample counters, the Current Samples Counter and the
Total Samples Counter. These two counters can be used to guarantee that the DS1616 data has not been
cleared at any time during a given period of time. The Current Samples Counter counts the number of
samples that have occurred since the most recent data acquisition operation was started (i.e., the number
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