Datasheet

Logic
Delay
< = 8 .3 ns
ADS7229
# 3
QD
CLK
Logic
Delay
< = 8 .3 ns
ADS7229
# 2
QD
CLK
Logic
Delay
< = 8 .3 ns
ADS7229
# 1
QD
CLK
SCLKinput
SDO
SDO
SDO
CDI
CDI
CDI
Serialdata
input
Serialdata
output
Logic
Delay
PlusPAD
2.7ns
Logic
Delay
PlusPAD
2.7ns
Logic
Delay
PlusPAD
8.3ns
Logic
Delay
PlusPAD
8.3ns
Logic
Delay
PlusPAD
2.7ns
Logic
Delay
PlusPAD
8.3ns
RESET
Intermediate
Latch
SAR Shift
Register
Output
Register
Conversion Clock
SW RESET
POR
SET
Latched by Falling Edge of CS
Latched by End Of
Conversion
EOC
SDO
SCLK
CS
EOC
CDI
ADS7229
ADS7230
www.ti.com ............................................................................................................................................................... SBAS437A – MAY 2008 – REVISED JUNE 2009
SCLK skew between converters and data path delay through the converters configured in chain mode can affect
the maximum frequency of SCLK. The delay can also be affected by supply voltage and loading. It may be
necessary to slow down the SCLK when the devices are configured in chain mode. Figure 65 shows a typical
delay process through multiple converters linked in daisy-chain mode.
Figure 65. Typical Delay Through Converters Configured in Chain Mode
The converter has two reset mechanisms: a power-on reset (POR) and a software reset using CFR_D0. These
two mechanisms are NOR-ed internally. When a reset (software or POR) is issued, all register data are set to the
default values (all 1s) and the SDO output (during the cycle immediately after reset) is set to all 1s. The state
machine is reset to the power-on state. Figure 66 illustrates the digital output under a reset condition.
Figure 66. Digital Output Under Reset Condition
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