Datasheet
EVM Analog Input
2-3
Circuit Description
The amplifier output circuit is connected to the TLC5540/TLC5510/
TLC5510A by soldering a jumper between terminals E10 and E12.
The amplifier input can be either dc-coupled or ac-coupled to the ADC input.
Table 2–1 shows the jumpers required to select either input coupling method.
Table 2–1.Amplifier Input Coupling
Coupling Jumper Terminals
dc E3 to E4
ac E1 to E2
2.1.3 Amplifier Input, AC-Coupled
Potentiometer R2 controls the dc input bias for amplifier ac-coupled inputs.
This allows the bias to be varied from near ground to near 5 V/3.6 V (analog).
With an amplifier gain of two, the output approaches the positive power supply
when the bias potentiometer approaches 2.5 V for the TLC5510/TLC5540.
For a 4-V input and a gain of 1 (R6 removed and R8 set to 1 kΩ for optimum
settling time and minimum ringing) bias potentiometer R2 is adjusted such that
E1 is at 2 V and the amplifier output swing is 0 V to 4 V at TP2. With an amplifier
supply voltage of +5 V the output positive peak will be distorted slightly; there-
fore, it is necessary to adjust the 5-V supply to 5.56 V in order to prevent
clipping of the amplifier output voltage.
The low frequency response pole is dominated by the 4.7-µF capacitor (C6)
and the resistance setting of the potentiometer.
2.1.4 Input Bias Operational Range
Jumper J6 determines the signal input range (0 to full scale) at the analog input
of the TLC5540/TLC5510/TLC5510A. Table 2–2 shows the effects of J6.
Table 2–2.Input Voltage Setting
Jumper J6
TLC5540/TLC5510
Input Voltage Range
at 5 V
DDA
TLC5510A
Input Voltage Range
at 5 V
DDA
Removed 0.6 V to 2.6 V 0 V to 4 V (J11 and J16 installed)
Installed 0 V to 2.28 V 0 V to 4 V (J11 and J16 installed)
Other output ranges can be configured. See the TLC5540/TLC5510/
TLC5510A data sheets.
2.1.5 Test Points
Test points TP1 and TP2 provide an oscilloscope connection to monitor the
output of the analog input conditioning amplifier stage as shown in Table 2–3.
Table 2–3.Test Points
Test Point Connection
TP1 Analog ground
TP2 Analog output of THS3001