Connectors
3-7
Operation
Table 3−7. BT1: 9-V Battery Connector
Terminal Name
Function
Split (female) ring
Positive (mates with solid/male post on
battery)
Solid (male) ring
Negative (mates with split/female post on
battery)
3.3.4
J2: Analog Inputs
Terminal block J2 is the main analog input to the ADS1254EVM. Two terminals
are provided for each of the ADS1254 four differential inputs. Each terminal
is connected to the ADS1254 through a 1-k
Ω
resistor.
Table 3−8. J2: Analog Inputs
Terminal
Number
Terminal
Name
ADS1254
Pin
Function
1
CH4−
19
Channel 4 negative input
2
CH4+
20
Channel 4 positive input
3
CH3−
6
Channel 3 negative input
4
CH3+
5
Channel 3 positive input
5
CH2−
4
Channel 2 negative input
6
CH2+
3
Channel 2 positive input
7
CH1−
2
Channel 1 negative input
8
CH1+
1
Channel 1 positive input
3.3.5
J3: External Reference Input
The ADS1254EVM has an onboard 4.096-V bandgap reference. If a
lower-noise reference source or a reference with a different voltage is desired,
it can be connected to screw−terminal block J3. The reference source,
onboard or external, is selected using JMP3. Both the onboard and external
reference inputs are filtered and buffered by R2, C3, and U4, and bypassed
by C10.
It is also possible to supply a reference voltage directly to the ADS1254 by dis-
connecting JMP4 and connecting the reference to pin 2.
Table 3−9. J3: External Reference Input
Terminal Number
Function
1
External reference voltage input
2
Analog ground
Summary of Contents for ADS1254
Page 1: ... May 2002 Data Acquisition Products User s Guide SLAU083 ...
Page 34: ...3 18 ...
Page 36: ...Board Layouts 4 2 4 1 Board Layouts Figure 4 1 Board Layout Top Layer ...
Page 37: ...Board Layouts 4 3 Physical Description Figure 4 2 Board Layout Bottom Layer ...
Page 38: ...Schematics 4 4 4 2 Schematics The ADS1254 schematics are shown on the following pages ...
