MAX11040 Maxim Integrated Products, MAX11040 Datasheet - Page 27

• Manufacturer Part Number: MAX11040
• Description: Sigma-Delta ADC
• Manufacturer: Maxim Integrated Products

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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
MAX11040 to the SYNC input of all devices in the
chain. The MAX11040 ignores any SYNC transitions
applied during the power-on reset.
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 17. This minimizes the effects of drift
Figure 17. One Crystal per MAX11040 and All SYNC Inputs Driven by DRDYOUT of the Last Device in the Chain
MICROCONTROLLER
DSP OR
Multiple Device Synchronization
Using Independent XIN Clock Sources
Applications Information
______________________________________________________________________________________
Using a Shared XIN Clock Source
Synchronizing Multiple Devices
Synchronizing Multiple Devices
24-Bit, 4-Channel, Simultaneous-Sampling,
SYNC
CS
SCLK
DIN
CASCIN
DRDYIN
XIN
MAX11040
DEVICE 0
XOUT CLKOUT
CASCOUT
DRDYOUT
OVRFLW
FAULT
DOUT
CASCADE UP TO 8 DEVICES
Cascadable, Sigma-Delta ADC
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.
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 MAX11040’s
to a frequency slightly slower than the external frequen-
cy, such that SYNC falling edges only occur a short
time after the DRDYOUT signals.
SYNC
CS
SCLK
DIN
CASCIN
DRDYIN
XIN
MAX11040
DEVICE n
XOUT
CASCOUT
DRDYOUT
OVRFLW
FAULT
DOUT
to an Independent Clock Source
Synchronizing Multiple Devices
SYNC
CS
SCLK
DIN
CASCIN
DRDYIN
XIN
MAX11040
DEVICE n+1
XOUT
DRDYOUT
OVRFLW
FAULT
DOUT
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