LTC2440IGN#PBF Linear Technology, LTC2440IGN#PBF Datasheet - Page 25

• Manufacturer Part Number: LTC2440IGN#PBF
• Description: IC ADC DIFFER 24-BIT HS 16-SSOP
• Manufacturer: Linear Technology

Specifications of LTC2440IGN#PBF

• Number Of Bits: 24
• Sampling Rate (per Second): 3.5k
• Data Interface: MICROWIRE™, Serial, SPI™
• Number Of Converters: 2
• Power Dissipation (max): 40mW
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-SSOP (0.150", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
Table 6 lists the properties of the LTC2440 with various
combinations of oversample ratio and clock frequency.
Understanding these properties is the key to fi ne tuning
the characteristics of the LTC2440 to the application.
Maximum Conversion Rate
The maximum conversion rate is the fastest possible rate
at which conversions can be performed.
First Notch Frequency
This is the fi rst notch in the SINC
and depends on the fo clock frequency and the oversample
ratio. Rejection at this frequency and its multiples (up to
Table 6
*ADC noise increases by approximately √2 when OSR is decreased by a factor of 2 for OSR 32768 to OSR 256. The ADC noise at OSR 128 and OSR 64
include effects from internal modulator quantization noise.
Oversample
16384
32768
(OSR)
Ratio
1024
2048
4096
8192
128
256
512
64
Noise*
750nV
510nV
375nV
250nV
200nV
3.5μV
1.4μV
23μV
ADC
2μV
1μV
(V
REF
ENOB
21.3
21.8
22.4
22.9
23.4
24.4
24.6
17
20
24
= 5V)*
4
Maximum Conversion Rate
9MHz clock
portion of the digital fi lter
3515.6
1757.8
Internal
878.9
439.5
219.7
109.9
54.9
27.5
13.7
6.9
f
f
f
f
O
f
f
f
f
O
O
O
f
f
O
O
O
O
/1310720
External
O
O
/163840
/327680
/655360
/10240
/20480
/40960
/81920
/2560
/5120
f
O
9MHz cloc
First Notch Frequency
14062.5
7031.3
3515.6
1757.8
Internal
28125
878.9
439.5
219.7
109.9
54.9
the modulator sample rate of 1.8MHz) exceeds 120dB.
This is 8 times the maximum conversion rate.
Effective Noise Bandwidth
The LTC2440 has extremely good input noise rejection from
the fi rst notch frequency all the way out to the modulator
sample rate (typically 1.8MHz). Effective noise bandwidth
is a measure of how the ADC will reject wideband input
noise up to the modulator sample rate. The example on
the following page shows how the noise rejection of the
LTC2440 reduces the effective noise of an amplifi er driv-
ing its input.
k
f
f
f
f
f
f
f
f
O
External
f
f
O
O
O
O
O
O
O
O
O
/16380
/1280
/2560
/5120
/1020
/2050
/4100
/8190
/320
/640
f
O
9MHz clock
Internal
Effective Noise BW
3148
1574
98.4
49.2
24.6
12.4
787
394
197
6.2
f
f
f
f
O
f
f
f
f
O
O
O
f
f
O
O
O
O
/1463000
External
O
O
/183000
/366000
/731000
/11400
/22800
/45700
/91400
/2850
/5700
f
O
9MHz clock
Internal
1696
26.5
13.2
LTC2440
848
424
212
106
6.6
3.3
53
–3dB Point (Hz)
f
f
f
f
f
O
O
f
f
f
f
O
O
O
f
O
O
O
O
/1358000
/2717000
External
O
/170000
/340000
/679000
25
/10600
/21200
/42500
/84900
/5310
f
O
2440fd