MAX11253 Datasheet, PDF (24/51 Pages) Maxim Integrated Products – Longer Battery Life for Portable Applications

MAX11253
16-Bit, 6-Channel, 64ksps, 6.2nV/√Hz PGA,
Delta-Sigma ADC with SPI Interface
SEQUENCER MODE 1
DEL CHANNEL CONVERSION
SEQ:MDREN • DELAY:MUX
SEQ:MUX[2:0]
Figure 9. Sequencer Mode 1 Timing Diagram
SEQUENCER MODE 2
DEL
CHANNEL
CONVERSION
DEL
CHANNEL
CONVERSION
DEL
CHANNEL
CONVERSION
DEL
CHANNEL
CONVERSION
DEL
CHANNEL
CONVERSION
DEL
CHANNEL
CONVERSION
SEQ:MDREN •
DELAY:MUX
SEQ:MDREN •
DELAY:MUX
SEQ:MDREN •
DELAY:MUX
SEQ:MDREN •
DELAY:MUX
SEQ:MDREN •
DELAY:MUX
SEQ:MDREN •
DELAY:MUX
CHANMAP:ORD[2:0] = 001 CHANMAP:ORD[2:0] = 010 CHANMAP:ORD[2:0] = 011 CHANMAP:ORD[2:0] = 100 CHANMAP:ORD[2:0] = 101 CHANMAP:ORD[2:0] = 110
Figure 10. Sequencer Mode 2 Timing Diagram
Programming Sequence
Mode Entry
1) Set up the following registers: SEQ, CHMAP0,
CHMAP1, DELAY, GPO_DIR, GPIO_CTRL, CTRL1
a. SEQ:MODE[1:0] = ‘01’ for sequencer mode 2
b. If desired set SEQ:RDYBEN to ‘1’ to signal data
ready only when all channel conversions are com-
pleted
c. Enable SEQ:MDREN to delay conversion start to
allow for input settling. Set DELAY:MUX[7:0] to the
desired conversion delay
d. Set CHMAP0 and CHMAP1 to select the channels
and channel order for conversion
e. Set CTRL1:PD[1:0] to STANDBY or SLEEP state
to set the desired exit state if a conversion com-
mand with MODE[1:0] set to ‘01’ is issued during
the conversion
f. Set register GPO_DIR and GPIO_CTRL to enable or
disable the desired GPO and GPIO pins
g. Set CTRL1:SCYCLE = ‘1’ for single-cycle conver-
sion mode
2) Write a conversion command (see Table 4).
a. Set data rate using bits RATE[3:0] of the command
byte
b. Set MODE[1:0] of the command byte to ‘11’
3) Monitor RDYB (if SEQ:RDYBEN=’0’) and bits
STAT:SRDY[5:0] for availability of per channel conver-
sion results in DATA[x] registers.
Mode Exit
1) This mode exits to SLEEP state upon completion of
sequencing all channels
2) To interrupt current sequencing perform mode exit,
see the Changing SEQUENCER Modes—Mode Exit
section. This device is put in STANDBY or SLEEP
state based on CTRL1:PD[1:0] set in step 1(e) of
Mode Entry section.
SEQUENCER MODE 3 – Scan, With Sequenced
GPO Controls
This mode is used to sequentially convert a programmed
set of channels in a preset order and sequence the
GPO/GPIO pins concurrently. The GPO/GPIO pins are
used to bias external circuitry such as bridge sensors;
the common reference (GPOGND) is typically ground.
After all channel conversions have completed, the
MAX11253 automatically powers down into SLEEP
mode. Figure 11 illustrates the Sequencer Mode 3
timing diagram for a three-channel scan. As long as
CTRL3:GPO_MODE is set to ‘1’, registers GPO_DIR and
GPIO_CTRL are ignored in this mode, as the GPO/GPIO
pins are controlled by the sequencer.
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