LTC2415-1CGN Linear Technology, LTC2415-1CGN Datasheet - Page 32

• Manufacturer Part Number: LTC2415-1CGN
• Description: IC ADC 24BIT DIFFINPUT/REF16SSOP
• Manufacturer: Linear Technology

Specifications of LTC2415-1CGN

• Number Of Bits: 24
• Sampling Rate (per Second): 13.75
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 1mW
• Voltage Supply Source: Single Supply
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

LTC2415/LTC2415-1
APPLICATIO S I FOR ATIO
Normal Mode Rejection, Output Rate and Running
Averages
The LTC2415/LTC2415-1 both contain an identical Sinc
digital filter (see Figures 30 and 31) which offers excellent
line frequency noise rejection. For the LTC2415, a notch
frequency of either 50Hz or 60Hz (see Figure 32) is user
selectable by tying pin F
other hand, the LTC2415-1 offers simultaneous rejection
of 50Hz and 60Hz by tying F
frequency to approximately 55Hz (see Figure 32).
At a notch frequency of 55Hz, the LTC2415-1 rejects 50Hz
better than 87dB rejection of both 50Hz and 60Hz 2%, a
32
Figure 30. Rejection vs Frequency at V
–100
–120
2% and 60Hz 2% better than 72dB. In order to achieve
–20
–40
–60
–80
0
1
–100
–100
–120
–130
–140
50
–80
–90
Figure 33. Normal Mode Rejection
when Using an Internal Oscillator
FREQUENCY AT V
48
DIFFERENTIAL INPUT SIGNAL FREQUENCY (Hz)
100
50
52
U
150
IN
54
(Hz)
O
high or Low, respectively. On the
V
V
V
F
200
O
CC
REF
IN
U
= 0
56
= 2.5V
= 5V
= 5V
2415 F30
O
58
250
low. This sets the notch
60
IN
W
2415 F33
62
Figure 31. Rejection vs Frequency at V
–140
–100
–120
–20
–40
–60
–80
0
0
U
INPUT FREQUENCY
–100
–120
–20
–40
– 60
–80
4
0
f
S
0
/2
Figure 34. Input Normal Mode Rejection vs Input
Frequency with Input Perturbation of 100% of Full Scale
running average can be performed. By averaging two
consecutive ADC readings, a Sinc
the Sinc
shown in Figures 33 and 34. In order to preserve the 2
output rate, adjacent results are averaged with the follow-
ing algorithm:
20
Result 1 = average (sample 0, sample 1)
Result 2 = average (sample 1, sample 2)
Result 3 = average (sample 2, sample 3)
…
Result N = average (sample n-1, sample n)
40
2415 F31
4
f
digital filter yielding the frequency response
S
60
IN
80
INPUT FREQUENCY (Hz)
100
INPUT FREQUENCY DEVIATION FROM NOTCH FREQUENCY (%)
Figure 32. Rejection vs Frequency at V
–100
–110
–120
–130
–140
–60
–70
–80
–90
–12
120
MEASURED DATA
CALCULATED DATA
–8
140
1
–4
notch is combined with
160
0
180
V
REF
REF
V
V
T
A
CC
INCM
IN(P-P)
4
= 25 C
+
–
= 5V
= 5V
200
= GND
= 2.5V
= 5V
sn2415 24151fs
8
2415 F34
2415 F32
220
12
IN