Datasheet

1 2
3
4 5 6 7 8
124 125
126
127 128 129 130 131
STI #1
CLK
#1,2
OUTP –
OUTM <1># 1
OUTP –
OUTM <0># 1
STO #1= STI #2
132
Ch63
Ch31
Ch62
Ch30
Ch32
Ch0Ch1
133
OUTP –
OUTM <1># 2
OUTP –
OUTM <0># 2
Ch127
Ch95
Ch126
Ch94
Ch96
Ch64Ch65
DataRead
AFE0064
SLAS672 –SEPTEMBER 2009 ........................................................................................................................................................................................ www.ti.com
Figure 8. Data Read with Two Devices in Cascade
This mode allows the use of a single, four channel, 15 MHz (or more) ADC for digitizing the data from 128
channels in single scan. In this mode the effective maximum data transfer rate is 15 MHz.
TFT Charge Injection Compensation: The AFE0064 allows compensation for the charge injected by the TFT
during turn on and turn off. During turn on, typically a TFT injects a positive charge forcing the integrator output
below zero. One way to handle this is to allow negative swing on the integrator. In that case the pixel charge is
integrated from the –ve value resulting from TFT charge injection. For this scheme the device output dynamic
range covers all voltage levels starting from fixed –ve voltage arising from maximum anticipated charge injection
to maximum positive voltage from the integrator. This can result in loss of dynamic range in the case where TFT
charge injection is less than the maximum anticipated charge injection.
To overcome this problem, the AFE0064 provides a special feature to compensate for positive or negative
charge during TFT turn on and opposite polarity charge during TFT turn off. The user can adjust the
compensation charge with the help of external voltage on the VTEST-A and VTEST-B pins.
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