XE8805 SEMTECH [Semtech Corporation], XE8805 Datasheet - Page 116

• Manufacturer Part Number: XE8805
• Description: Data Acquisition MCU
• Manufacturer: SEMTECH [Semtech Corporation]

16.8.7
Figure 16-25 shows power supply rejection ratio (PSRR) at 3V and 5V supply voltage, and for various PGA gains.
PSRR is defined as the ratio (in dB) of voltage supply change (in V) to the change in the converter output (in V).
PSRR depends on both PGA gain and supply voltage V
© Semtech 2006
-10
-15
-20
15
10
-5
5
0
Figure 16-24. (a) Absolute and (b) relative change in quiescent curent consumption vs. RC oscillator
0
Table 16-28. Typical quiescent current distributions in acquisition chain (n = 16 bits, f
Power Supply Rejection Ratio
500
1000
Frequency - f
V
V
Supply
DD
DD
1500
= 5V
= 3V
2000
RC
[kHz]
(a)
2500
ADC
250
190
Figure 16-25. Power supply rejection ratio (PSRR)
3000
105
100
95
90
85
80
75
70
65
60
frequency (all PGAs active, V
PGA1
3500
165
150
VDD=3V
VDD=5V
1
PGA2
5
130
120
850
800
750
700
650
600
550
500
PGA Gain [V/V]
16-30
DD
0
.
10
PGA3
175
160
500
20
1000
Frequency - f
TOTAL
720
620
1500
DD
100
= 5V)
2000
RC
Unit
[kHz]
µA
µA
(b)
2500
3000
XE8805/05A
3500
www.semtech.com
S
= 500kHz)