MAX1027/MAX1029/MAX1031
10-Bit 300ksps ADCs with FIFO,
Temp Sensor, Internal Reference
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set to 1. Select scan mode 10 to scan the same channel
multiple times. Clock mode 11 disables averaging.
Reset Register
Write to the reset register (as shown in Table 7) to clear
the FIFO or to reset all registers to their default states.
Set the RESET bit to 1 to reset the FIFO. Set the reset
bit to zero to return the MAX1027/MAX1029/MAX1031
to its default power-up state.
Power-Up Default State
The MAX1027/MAX1029/MAX1031 power up with all
blocks in shutdown, including the reference. All registers
power up in state 00000000, except for the setup regis-
ter, which powers up in clock mode 10 (CKSEL1 = 1).
Temperature Measurements
The MAX1027/MAX1029/MAX1031 perform tempera-
ture measurements with an internal diode-connected
transistor. The diode bias current changes from 68µA
to 4µA to produce a temperature-dependent bias volt-
age difference. The second conversion result at 4µA is
subtracted from the first at 68µA to calculate a digital
value that is proportional to absolute temperature. The
output data appearing at DOUT is the above digital
code minus an offset to adjust from Kelvin to Celsius.
The reference voltage used for the temperature mea-
surements is derived from the internal reference source
to ensure a resolution of 1/8 of a degree.
Output Data Format
Figures 4–7 illustrate the conversion timing for the
MAX1027/MAX1029/MAX1031. The 10-bit conversion
result is output in MSB-first format with four leading
zeroes and two trailing sub-bits. The 12-bit temperature
measurement is output with four leading zeros. DIN
data is latched into the serial interface on the rising
edge of SCLK. Data on DOUT transitions on the falling
edge of SCLK. Conversions in clock modes 00 and 01
are initiated by CNVST. Conversions in clock modes 10
and 11 are initiated by writing an input data byte to the
conversion register. Data is binary for unipolar mode and
two’s complement for bipolar mode.
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