AD7873 Analog Devices, AD7873 Datasheet - Page 12

• Manufacturer Part Number: AD7873
• Description: Touch Screen Digitizer
• Manufacturer: Analog Devices

Specifications of AD7873

• Resolution (bits): 12bit
• # Chan: 6
• Sample Rate: 125kSPS
• Interface: Ser
• Analog Input Type: SE-Uni
• Ain Range: Uni (Vref),Uni 2.5V
• Adc Architecture: SAR
• Pkg Type: CSP,SOP

AD7873
–100
–120
–20
–40
–60
–80
0
0
V
100mV p-p SINE WAVE ON +V
V
f
SAMPLE
Figure 23. AC PSRR vs. Supply Ripple Frequency
CC
REF
10
= 3V
= 2.5V EXT REFERENCE
= 125kHz,
20
V
CC
30
RIPPLE FREQUENCY (kHz)
f
IN
40
= 20kHz
50
CC
60
70
80
90
100
Rev. E | Page 12 of 28
Figure 23 shows the power supply rejection ratio vs. V
frequency for the AD7873. The power supply rejection ratio is
defined as the ratio of the power in the ADC output at full-scale
frequency, f, to the power of a 100 mV sine wave applied to the
ADC V
where:
Pf is power at frequency, f, in ADC output.
Pf
Here a 100 mV p-p sine wave is coupled onto the V
Decoupling capacitors of 10 μF and 0.1 μF were used on the supply.
s
is power at frequency, f
PSSR (dB) = 10log(Pf/Pf
CC
supply of frequency f
s
, coupled onto the ADC V
s
)
S
CC
CC
supply.
DD
supply.
supply