Datasheet

R
X
C
X
RESET
INT
SCL
SDA
CH0
CH1
CH2
CH3
1
2
3
4
12
11
10
9
DVDD
16
A0
5
AVDD
15
DGND
6
ADCIN
14
PWRCON
7
MUXOUT
13
AGND
8
ADS7924
SensorSignals
MSP430
Microcontroller
DVDD
AVDD
1 Fm
1 Fm
3kW 3kW
ADS7924
www.ti.com SBAS482A –JANUARY 2010–REVISED MAY 2010
Op Amp Power-Up Time
The TLV2780 typically powers up from a shutdown state in 800ns. This period is well within the ADS7924
minimum acquisition time of 6ms. Setting the PWRCONFIG register (address = 15h) allows for more time if
another op amp with a shutdown feature is used.
Using an RC Filter
For applications where low output impedance signals are provided for the ADS7924 inputs, a simple RC filter
may suffice, as shown in Figure 37.
NOTE: f
–3dB
BW = 159kHz, R = 1kΩ, and C = 1nF where R = R
MUX
+ R
SENSOR
+ R
X
, C = C
X
+ C
ADCIN
, R
MUX
is approximately 60Ω, and
C
ADCIN
is approximately 15pF.
Figure 37. Sensor Data Acquisition with Filter Only
C
X
should be greater than 200pF, if possible. When coupled directly to the ADC input, using a capacitor with this
value allows for faster settling when scanning between channels.
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Product Folder Link(s): ADS7924