MAX144 Datasheet, PDF (11/16 Pages) Maxim Integrated Products – +2.7V, Low-Power, 2-Channel, 108ksps, Serial 12-Bit ADCs in 8-Pin μMAX

+2.7V, Low-Power, 2-Channel, 108ksps,
Serial 12-Bit ADCs in 8-Pin µMAX
DOUT valid timing characteristic. Data should be
clocked into the µP on SCLK’s rising edge.
4) Pull CS/SHDN high at or after the 16th falling clock
edge. If CS/SHDN remains low, trailing zeros will be
clocked out after the LSB.
5) With CS/SHDN high, wait at least 60ns (t_CS) before
starting a new conversion by pulling CS/SHDN low.
A conversion can be aborted by pulling CS/SHDN
high before the conversion ends; wait at least 60ns
before starting a new conversion.
Data can be output in two 8-bit sequences or continu-
ously. The bytes will contain the result of the conversion
padded with three leading ones and the channel identi-
fication before the MSB. If the serial clock hasn’t been
idled after the last LSB and CS/SHDN is kept low,
DOUT sends trailing zeros.
SPI and MICROWIRE Interface
When using SPI (Figure 8a) or MICROWIRE (Figure 8b)
interfaces, set CPOL = 0 and CPHA = 0. Conversion
begins with a falling edge on CS/SHDN (Figure 8c).
Two consecutive 8-bit readings are necessary to obtain
the entire 12-bit result from the ADC. DOUT data transi-
tions on the serial clock’s falling edge and is clocked
into the µP on SCLK’s rising edge. The first 8-bit data
stream contains three leading ones, the channel identi-
CS/SHDN
SCLK
t_SCLKS
•••
t_CH
t_CL
•••
t_DV
DOUT
HIGH-2
t_DO
•••
Figure 7. Detailed Serial-Interface Timing Sequence
t_CS
t_TR
HIGH-2
I/O
SCK
MISO
SPI
V_DD
SS
CS/SHDN
SCLK
DOUT
MAX144
MAX145
I/O
SK
SI
MICROWIRE
CS/SHDN
SCLK
DOUT
MAX144
MAX145
Figure 8a. SPI Connections
8b. MICROWIRE Connections
SCLK
CS/SHDN
1ST BYTE READ
1 2345678
DOUT*
CHID D11 D10 D9 D8
D7
SAMPLING INSTANT MSB
*WHEN CS/SHDN IS HIGH, DOUT = HIGH-Z
Figure 8c. SPI/MICROWIRE Interface Timing Sequence (CPOL = CPHA = 0)
2ND BYTE READ
9 10 11 12 13 14 15 16
D6 D5 D4 D3 D2 D1 D0
LSB
HIGH-Z
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