MAX1298_12 Datasheet, PDF(13/20 Page) Maxim Integrated Products – 12-Bit Serial-Output Temperature Sensors with 5-Channel ADC

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MAX1298_12 Datasheet, PDF (13/20 Pages) Maxim Integrated Products – 12-Bit Serial-Output Temperature Sensors with 5-Channel ADC

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12-Bit Serial-Output Temperature Sensors

with 5-Channel ADC

SSTRB

FCLK

13 fCLKs

WARMUP

INPUT

ACQUISITION

fCLKs

CONVERSION CYCLE 1

REF

ACQUISITION 1 REF

ACQUISITION 2

44 fCLKs

CONVERSION CYCLES 2â12

REFERENCE SAMPLING

3 fCLKs

WRITE TO OUTPUT

Figure 3a. Voltage Conversion Timing Diagram

SSTRB

FCLK

13 fCLKs

WARMUP

INPUT

ACQUISITION

4 fCLKs

CONVERSION CYCLE 1

44 fCLKs

CONVERTION

CYCLES 2â12

REFERENCE

SAMPLING

FIRST CONVERSION

Figure 3b. Temperature Conversion Timing Diagram

maximum time the device takes to acquire the signal.

Calculate this with the following equation:

tACQ = 7 (RS + RIN) CIN

where RS is the source impedance of the input signal,

RIN is the T/H input impedance (40kâ¦), and CIN is the

input sampling capacitance of the ADC (4pF). Source

impedances below 100kâ¦ have no significant effect on

MAX1298/MAX1299 AC performance.

Analog Input Protection

Internal protection diodes clamp the analog inputs to

VDD and GND, so channels can swing within GND -

0.3V and VDD + 0.3V without damage. However, for

accurate conversions, the inputs should not extend

beyond the supply rails.

13 fCLKs

WARMUP

INPUT

ACQUISITION

48 fCLKs

CONVERTION CYCLES 1â12

SECOND CONVERSION

3 fCLKs

SUBTRACTION

AND WRITE TO

OUTPUT REGISTER

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 ÂµP control registers. Figure 4

shows detailed serial interface timing information. See

Tables 2â5 for programming information.

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