LTC2410 Linear Technology, LTC2410 Datasheet - Page 31

• Manufacturer Part Number: LTC2410
• Description: 24-Bit No Latency ADC with Differential Input and Differential Reference
• Manufacturer: Linear Technology

APPLICATIO S I FOR ATIO
SYNCHRONIZATION OF MULTIPLE LTC2410s
Since the LTC2410’s absolute accuracy (total unadjusted
error) is 5ppm, applications utilizing multiple synchro-
nized ADCs are possible.
Simultaneous Sampling with Two LTC2410s
One such application is synchronizing multiple LTC2410s,
see Figure 44. The start of conversion is synchronized to
the rising edge of CS. In order to synchronize multiple
LTC2410s, CS is a common input to all the ADCs.
To prevent the converters from autostarting a new con-
version at the end of data output read, 31 or fewer SCK
clock signals are applied to the LTC2410 instead of 32 (the
32nd falling edge would start a conversion). The exact
timing and frequency for the SCK signal is not critical
since it is only shifting out the data. In this case, two
LTC2410’s simultaneously start and end their conversion
cycles under the external control of CS.
SDO1
SDO2
SCK1
SCK2
CS
U
U
CONTROLLER
W
SDO1
SDO2
SCK2
SCK1
Figure 44. Synchronous Conversion—Extendable
CS
31 OR LESS CLOCK CYCLES
U
V
REF
REF
IN
IN
GND
CC
+
–
LTC2410
+
–
#1
SDO
SCK
CS
F
O
Increasing the Output Rate Using Mulitple LTC2410s
A second application uses multiple LTC2410s to increase
the effective output rate by 4 , see Figure 45. In this case,
four LTC2410s are interleaved under the control of sepa-
rate CS signals. This increases the effective output rate
from 7.5Hz to 30Hz (up to a maximum of 60Hz). Addition-
ally, the one-shot output spectrum is unfolded allowing
further digital signal processing of the conversion results.
SCK and SDO may be common to all four LTC2410s. The
four CS rising edges equally divide one LTC2410 conver-
sion cycle (7.5Hz for 60Hz notch frequency). In order to
synchronize the start of conversion to CS, 31 or less SCK
clock pulses must be applied to each ADC.
Both the synchronous and 4 output rate applications use
the external serial clock and single cycle operation with
reduced data output length (see Serial Interface Timing
Modes section and Figure 6). An external oscillator clock
is applied commonly to the F
order to synchronize the sampling times. Both circuits
may be extended to include more LTC2410s.
31 OR LESS CLOCK CYCLES
V
REF
REF
IN
IN
GND
CC
+
LTC2410
–
+
–
#2
SDO
SCK
CS
F
O
V
V
EXTERNAL OSCILLATOR
(153,600HZ)
REF
REF
+
–
O
pin of each LTC2410 in
LTC2410
2410 F44
31