MAX1298 Datasheet, PDF (13/20 Pages) Maxim Integrated Products – 12-Bit Serial-Output Temperature Sensors with 5-Channel ADC

12-Bit Serial-Output Temperature Sensors
with 5-Channel ADC
SSTRB
FCLK
13 f_CLKs
WARMUP
INPUT
ACQUISITION
f_CLKs
CONVERSION CYCLE 1
REF
ACQUISITION 1 _REF
ACQUISITION 2
44 f_CLKs
CONVERSION CYCLES 2–12
REFERENCE SAMPLING
3 f_CLKs
WRITE TO OUTPUT
REGISTER
Figure 3a. Voltage Conversion Timing Diagram
SSTRB
FCLK
13 f_CLKs
WARMUP
INPUT
ACQUISITION
4 f_CLKs
CONVERSION CYCLE 1
44 f_CLKs
CONVERTION
CYCLES 2–12
REFERENCE
SAMPLING
FIRST CONVERSION
Figure 3b. Temperature Conversion Timing Diagram
input sampling capacitance of the ADC (4pF). Source
impedances below 100kΩ have no significant effect on
MAX1298/MAX1299 AC performance.
Analog Input Protection
Internal protection diodes clamp the analog inputs to
V_DD and GND, so channels can swing within GND -
0.3V and V_DD + 0.3V without damage. However, for
accurate conversions, the inputs should not extend
beyond the supply rails.
If an off-channel analog input extends beyond the
supply rails, limit the input current to 2mA.
13 f_CLKs
WARMUP
INPUT
ACQUISITION
48 f_CLKs
CONVERTION CYCLES 1–12
SECOND CONVERSION
3 f_CLKs
SUBTRACTION
AND WRITE TO
OUTPUT REGISTER
Serial Digital Interface
The MAX1298/MAX1299 feature a serial interface that is
fully compatible with SPI, QSPI, and MICROWIRE
devices. For SPI/QSPI, ensure that the CPU serial inter-
face runs in master mode so it generates the serial
clock signal. Select a 2.5MHz clock frequency or less,
and set zero values for clock polarity (CPOL) and
phase (CPHA) in the µP control registers. Figure 4
shows detailed serial interface timing information. See
Tables 2–5 for programming information.
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