Rainbow Electronics MAX1299 - Manual (Page 13)

13 f CLKs
WARMUP
44 f CLKs
CONVERTION
CYCLES 2–12
REFERENCE
SAMPLING
3 f CLKs
SUBTRACTION
AND WRITE TO
OUTPUT REGISTER
48 f CLKs
CONVERTION CYCLES 1–12
13 f CLKs
WARMUP
INPUT
ACQUISITION
INPUT
ACQUISITION
SSTRB
FCLK
4 f
CLKs
CONVERSION CYCLE 1
FIRST CONVERSION SECOND CONVERSION
MAX1298/MAX1299
12-Bit Serial-Output Temperature Sensors
with 5-Channel ADC
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input sampling capacitance of the ADC (4pF). Source
impedances below 100k
Ω 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.
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.
13 f
CLKs
WARMUP
3 f
CLKs
WRITE TO OUTPUT
REGISTER
INPUT
ACQUISITION
f
CLKs
SSTRB
FCLK
REF
ACQUISITION 1
REF
ACQUISITION 2
44 f CLKs
CONVERSION CYCLE 1
CONVERSION CYCLES 2–12
REFERENCE SAMPLING
Figure 3b. Temperature Conversion Timing Diagram
Figure 3a. Voltage Conversion Timing Diagram