Rainbow Electronics MAX1068 - Manual (Page 14)

MAX1067/MAX1068
Digital Interface
T h e M A X 1 0 6 7 / M A X 1 0 6 8 f e a t u r e a n S P I / Q S P I /
MICROWIRE-compatible 3-wire serial interface. The
MAX1067 digital interface consists of digital inputs CS,
SCLK, and DIN; and outputs DOUT and EOC. The
MAX1067 operates in the following modes:
• SPI interface with external clock
• SPI interface with internal clock
• SPI interface with internal clock and scan mode
In addition to the standard 3-wire serial interface modes,
the MAX1068 includes a DSPR input and a DSPX output
for communicating with DSPs in external clock mode
and a DSEL input to determine 8-bit-wide or 16-bit-wide
data-transfer mode. When not using the MAX1068 in the
DSP interface mode, connect DSPR to DV
DD and leave
DSPX unconnected.
Command/Configuration/Control Register
Table 1 shows the contents of the command/configura-
tion/control register and the state of each bit after initial
power-up. Tables 2–6 define the control and configura-
tion of the device for each bit. Cycling the power sup-
plies resets the command/configuration/control register
to the power-on-reset default state.
Initialization After Power-Up
A logic high on CS places the MAX1067/MAX1068 in the
shutdown mode chosen by the power-down bits, and
places DOUT in a high-impedance state. Drive CS low to
power-up and enable the MAX1067/MAX1068 before
starting a conversion. In internal reference mode, allow
5ms for the shutdown internal reference and/or buffer to
wake and stabilize before starting a conversion. In exter-
nal reference mode (or if the internal reference is already
on), no reference settling time is needed after power-up.
Multichannel, 14-Bit, 200ksps Analog-to-Digital
Converters
14 ______________________________________________________________________________________
SCLK
DOUT
AGND
DGND
AIN0
REF
AV DD
DV DD
DOUT
SCLK
CS
+5V
DIN
ANALOG
INPUTS
+5V
1 µF
0.1 µF
0.1 µF
GND
MAX1067
0.1 µF
AIN1
AIN2
AIN3
DIN
EOC EOC
AGND
REFCAP
CS
Figure 5. MAX1067 Typical Operating Circuit
SCLK
DOUT
AGND
DGND
AIN0
REF
AV DD
DV DD
DOUT
SCLK
CS
+5V
16
8
DIN
ANALOG
INPUTS
+5V
1 µF
0.1 µF
0.1 µF
GND
MAX1068
0.1 µF
AIN1
AIN2
AIN3
AIN4
AIN5
AIN6
AIN7
DIN
DSEL
DSPR
DSPX DSPX
EOC
AGND
REFCAP
EOC
CS
Figure 6. MAX1068 Typical Operating Circuit
AUTO-ZERO
RAIL
CAPACITIVE
DAC
C DAC
REF
AGND
TRACK
HOLD
HOLD TRACK
ZERO
MUX
R IN
R DSON
AIN_
C MUX
C SWITCH
Figure 7. Equivalent Input Circuit
BIT7 (MSB) BIT6 BIT5 BIT4 BIT3 BIT2 BIT1 BIT0 (LSB)
COMMAND
CH SEL2 CH SEL1 CH SEL0 SCAN1 SCAN0 REF/PD_SEL1 REF/PD SEL0 INT/EXT CLK
POWER-UP
STATE
0 0 0 0 0 1 1 0
Table 1. Command/Configuration/Control Register