Texas Instruments ADS848 EVM Series User Manual page 7

www.ti.com
Conversions are initiated on the falling edge of the convert start signal. It is therefore critical to provide a
clean, low-jitter, Convert Start (CONVST) pulse when measuring large amplitude and/or high-frequency
input signals.
The CONVST signal can be applied to the ADS848x from the decoder outputs, at J6 pin 5, or from
connector P3 pin 17. Address decoder SN74ACH138 can be used to generate the Read (RD) and
CONVST signals to the converter. Jumpers W3 and W4 allow the user to assign these two signals to
different addresses in memory. This option allows for the stacking of up to two ADS848xEVMs into
processor memory. See
17, it is then necessary to short W6 pins 1-2. This configuration bypasses the decoder output selected by
the position of W4.
Note: The evaluation module does not allow the Chip Select (CS) line of the converter to be
assigned to different memory locations. It is therefore suggested that the CS line be
grounded or wired to an appropriate signal of the processor.
Reference
Designator
Set digital buffer supply voltage to +5 V
W1
Set digital buffer supply voltage to +3.3 V
Apply inverted BUSY to INTC signal
W2
Apply BUSY signal to INTC signal
Set RD signal to decoder output three [0x3].
W3
Set RD signal to decoder output four [0x4].
Set CONVST signal to decoder output one [0x1].
W4
Set CONVST signal to decoder output two [0x2].
W5 Set DC_CS to CS of ADS848x
Set DC_CONVST to CONVST of ADS848x.
W6
Set decoder output to CONVST of ADS848x.
(1)
Indicates factory-installed option.
The data bus is available at connector P2; see
Description
Data bit 0
Data bit 1
Data bit 2
Data bit 3
Data bit 4
Data bit 5
Data bit 6
Data bit 7
Data bit 8
Data bit 9
Data bit 10
Data bit 11
Data bit 12
Data bit 13
Data bit 14
SLAU186A – August 2006 – Revised September 2008
Submit Documentation Feedback
Table 4 for jumper settings. If a Convert Start signal is applied directly to P3 pin
Table 4. Jumper Settings
Description
Table 5
Table 5. Data Bus Connector P2
Signal Name Connector Pin No.
DB0 P2.1
DB1 P2.3
DB2 P2.5
DB3 P2.7
DB4 P2.9
DB5 P2.11
DB6 P2.13
DB7 P2.15
DB8 P2.17
DB9 P2.19
DB10 P2.21
DB11 P2.23
DB12 P2.25
DB13 P2.27
DB14 P2.29
Installed
Not Installed
Installed
Not installed
Installed
Not installed
Installed
Not Installed
Installed
Installed
Not installed
for pinout information.
Signal Name
P2.2 GND
P2.4 GN D
P2.6 GND
P2.8 GND
P2.10 GND
P2.12 GND
P2.14 GND
P2.16 GND
P2.18 GND
P2.20 GND
P2.22 GND
P2.24 GND
P2.26 GND
P2.28 GND
P2.30 GND
Digital Interface
Pin No.
1-2 2-3
(1)
Not installed
Installed
(1)
Not installed
Installed
(1)
Not installed
Installed
(1)
Not installed
Installed
(1)
N/A
(1)
Installed
(1)
Installed
Description
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
Ground
ADS848xEVM 7