MAX189BCPA Ver la hoja de datos (PDF) - Maxim Integrated

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MAX189BCPA

+5V, Low-Power, 12-Bit Serial ADCs

Maxim Integrated 

+5V, Low-Power, 12-Bit Serial ADCs

____________Applications Information

Connection to Standard Interfaces

The MAX187/MAX189 serial interface is fully compatible

with SPI, QSPI, and Microwire standard serial

interfaces.

If a serial interface is available, set the CPU’s serial

interface in master mode so the CPU generates the ser-

ial clock. Choose a clock frequency up to 2.5MHz.

1. Use a general-purpose I/O line on the CPU to pull CS

low. Keep SCLK low.

2. Wait the for the maximum conversion time specified

before activating SCLK. Alternatively, look for a

DOUT rising edge to determine the end of

conversion.

3. Activate SCLK for a minimum of 13 clock cycles. The

first falling clock edge will produce the MSB of the

DOUT conversion. DOUT output data transitions on

SCLK’s falling edge and is available in MSB-first for-

mat. Observe the SCLK to DOUT valid timing charac-

teristic. Data can be clocked into the µP on SCLK’s

rising edge.

4. Pull CS high at or after the 13th falling clock edge. If

CS remains low, trailing zeros are clocked out after

the LSB.

5. With CS = high, wait the minimum specified time, tCS,

before launching a new conversion by pulling CS

low. If a conversion is aborted by pulling CS high

before the conversions end, wait for the minimum

acquisition time, tACQ, before starting a new

conversion.

Data can be output in 1-byte chunks or continuously, as

shown in Figure 8. The bytes will contain the result of

the conversion padded with one leading 1, and trailing

0s if SCLK is still active with CS kept low.

1ST BYTE READ

2ND BYTE READ

SCLK

CS

HI-Z

tCONV

HI-Z

DOUT

MSB D10 D9 D8 D7 D6 D5

D4

D3 D2 D1 LSB

EOC

Figure 14. SPI/Microwire Serial Interface Timing (CPOL = CPHA = 0)

SCLK

CS

HI-Z

DOUT

tCONV

HI-Z

MSB D10 D9 D8 D7 D6 D5 D4 D3 D2 D1 LSB

EOC

Figure 15. QSPI Serial Interface Timing (CPOL = CPHA = 0)

______________________________________________________________________________________ 15

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