MAX11040K Datasheet, PDF (30/35 Pages) Maxim Integrated Products – 24-/16-Bit, 4-Channel, Simultaneous-Sampling, Cascadable, Sigma-Delta ADCs

24-/16-Bit, 4-Channel, Simultaneous-Sampling,
Cascadable, Sigma-Delta ADCs
Applications Information
Multiple Device Synchronization
Synchronizing Multiple Devices
Using a Shared XIN Clock Source
To synchronize multiple devices sharing a single XIN
clock source, transition the SYNC input that is shared
by all devices high to low. When an external sync
source is not available, connect DRDYOUT of one
device to the SYNC input of all devices in the chain.
The devices ignore any SYNC transitions applied dur-
ing the power-on reset.
Synchronizing Multiple Devices
Using Independent XIN Clock Sources
If it is undesirable to connect the XIN clock sources
together, due to EMI or other reasons; use DRDYIN,
DRDYOUT, and SYNC to align the conversion timing as
shown in Figure 18. This minimizes the effects of drift
between the clock sources by resynchronizing after
each conversion when DRDYOUT transitions low. In
this configuration, the maximum correction caused by a
SYNC edge is one XIN clock cycle.
The resulting sampling rate is determined by the sampling
frequency of the device with the slowest clock source,
plus the delay through the DRDYIN to DRDYOUT chain
between this slowest device and the end of the chain.
Synchronizing Multiple Devices
to an Independent Clock Source
To periodically synchronize multiple devices to an inde-
pendent timing source, connect the timing source to
the SYNC inputs of the devices. If minimal jitter is
important in the application, program the devices to a
frequency slightly slower than the external frequency,
such that SYNC falling edges only occur a short time
after the DRDYOUT signals.
DSP OR
MICROCONTROLLER
SYNC
CS
SCLK
DIN
MAX11040K
MAX11060
CASCIN
CASCOUT
DRDYIN
DRDYOUT
DEVICE 0
FAULT
OVRFLW
DOUT
XIN XOUT CLKOUT
SYNC
CS
SCLK
DIN
MAX11040K
MAX11060
CASCIN
CASCOUT
DRDYIN
DRDYOUT
DEVICE n
FAULT
OVRFLW
DOUT
XIN XOUT
SYNC
CS
SCLK
DIN
MAX11040K
MAX11060
CASCIN
DRDYOUT
DRDYIN
DEVICE n+1
FAULT
OVRFLW
DOUT
XIN XOUT
CASCADE UP TO 8 DEVICES
Figure 18. One Crystal per Device and All SYNC Inputs Driven by DRDYOUT of the Last Device in the Chain
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