MAX11270 Datasheet, PDF (42/46 Pages) Maxim Integrated Products – Integrated PGA

MAX11270
24-Bit, 10mW, 130dB SNR, 64ksps Delta-Sigma
ADC with Integrated PGA
SYNC PIN
tSYNC1
tSYNC2
SINC FILTER,
RDYB
tCNV
5 tCNV
...
1^ST CONVERSION READY
CLK
AFTER PULSE SYNCHRONIZATION
...
tR2
RISING EDGE OF SYNC PIN INITIATES A RESET, ABORTING THE CURRENT
CONVERSION AND STARTS A NEW CONVERSION
Figure 11. Synchronization Using Pulse Sync Mode Showing
Relationship Between SYNC, RDYB, and CLK Pins
TOP VIEW
DIN ¹
DOUT/MB0 2
DGND 3
SYNC 4
RSTB 5
GPIO3/MSYNC 6
GPIO2 7
GPIO1/MB1 8
AVDD 9
AVSS 10
AINN 11
AINP 12
+
MAX11270
TSSOP
24 _SCLK
23 CSB
22 DVDD
21 CAPREG
20 _DGND
19 CLK
18 _RDYB/ICLK
17 _AVSS
16 _CAPP
15 _CAPN
14 _REFP
13 REFN
Figure 12. Pin Configuration with MODBITS
Pulse Mode
Pulse or single event synchronization mode starts a new
conversion upon the rising edge of the SYNC pin. When
the SYNC pin is asserted the chip begins conversions
using the speed settings from the previous convert com-
mand, if no previous convert command was issued prior
to the SYNC pin asserting then the default conversion
speed of 1ksps is used. Note that convert start and SYNC
pin rising edge cannot be applied at the same time. Any
activity on the SYNC pin is ignored until after the first
RDYB assertion following a convert start. This is required
due to convert start overhead which delays the first con-
version result by 32 master clocks.
Modulator MODBITS Mode
The MODBITS mode bypasses the MAX11270’s internal
filters and outputs the real-time 5-bit modulator data to the
DOUT and GPIO pins.
MODBITS mode is controlled by the MODBITS and
ENMSYNC bits in the CTRL3 register.
Initializing MODBITS Mode
Set the CTRL3: MODBITS to 1 to enter the MODBITS
mode and read the real-time modulator output data. After
setting the control bits, a conversion command must be
issued. This starts the modulator without running the rest
of the digital logic needed for a full conversion. Setting
CTRL3: ENMSYNC = 1 enables the modulator SYNC puls-
es to shift out onto GPIO3/MSYNC. The modulator mode
can be run even if this bit is disabled. If ENMSYNC = 0,
the SYNC pulses will not be shifted out on GPIO3/MSYNC.
Exiting MODBITS Mode
To go back to normal conversion mode, set MODBITS = 0.
If MODBITS = 0, ENMSYNC is a don’t care. After setting
MODBITS = 0, issue a conversion command to activate
the MAX11270 in normal data read mode.
MODBITS Mode Pin Configurations
The DOUT/MB0, GPIO3/MSYNC, and GPIO1/MB1 pins
offer dual functionality, depending on whether MODBITS
real-time modulator data mode or normal data output
mode is selected.
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