LTC2377-20_15 Datasheet, PDF (19/30 Pages) Linear Technology – 20-Bit, 500ksps, Low Power SAR ADC with 0.5ppm INL

LTC2377-20
TIMING DIAGRAMS
Normal Mode, Multiple Devices
Figure 16 shows multiple LTC2377-20 devices operating
in normal mode (CHAIN = 0) sharing CNV, SCK and SDO.
By sharing CNV, SCK and SDO, the number of required
signals to operate multiple ADCs in parallel is reduced.
Since SDO is shared, the RDL/SDI input of each ADC must
be used to allow only one LTC2377-20 to drive SDO at a
time in order to avoid bus conflicts. As shown in Figure 16,
the RDL/SDI inputs idle high and are individually brought
low to read data out of each device between conversions.
When RDL/SDI is brought low, the MSB of the selected
device is output onto SDO.
CNV
CHAIN
LTC2377-20
SDO
B
RDL/SDI
SCK
CNV
CHAIN
BUSY
LTC2377-20
SDO
A
RDL/SDI
SCK
RDL_B
RDL_A
CONVERT
IRQ
DIGITAL HOST
DATA IN
CLK
237720 F16a
POWER-DOWN
ACQUIRE
CHAIN = 0
CONVERT
CNV
t_HOLD
BUSY
RDL/SDI_A
t_CONV
t_BUSYLH
POWER-DOWN
ACQUIRE
CONVERT
t_CNVL
RDL/SDI_B
SCK
SDO
t_EN
Hi-Z
t_SCK
1
2
3
18 19 20
t_SCKH
21
22
23
t_HSDO
t_DSDO
D19_A D18_A D17_A
t_DIS
D1_A D0_A
t_SCKL
Hi-Z
D19_B D18_B D17_B
38 39 40
D1_B D0_B
Figure 16. Normal Mode With Multiple Devices Sharing CNV, SCK and SDO
t_QUIET
Hi-Z
237720 F16
For more information www.linear.com/LTC2377-20
237720fa
19