Datasheet LTC2444, LTC2445, LTC2448, LTC2449 (Analog Devices) - 26
| Manufacturer | Analog Devices |
| Description | 24-Bit High Speed 8-/16-Channel ∆∑ ADCs with Selectable Speed/Resolution |
| Pages / Page | 30 / 26 — applicaTions inForMaTion. Figure 17. Simple External Clock Source. … |
| File Format / Size | PDF / 350 Kb |
| Document Language | English |
applicaTions inForMaTion. Figure 17. Simple External Clock Source. Maximum Conversion Rate. First Notch Frequency
Model Line for this Datasheet
- LTC2444CUHF#PBF LTC2444CUHF#PBF LTC2444CUHF#TRPBF LTC2444CUHF#TRPBF LTC2444IUHF#PBF LTC2444IUHF#PBF LTC2444IUHF#TRPBF LTC2444IUHF#TRPBF
- LTC2445CUHF#PBF LTC2445CUHF#PBF LTC2445CUHF#TRPBF LTC2445CUHF#TRPBF LTC2445IUHF#PBF LTC2445IUHF#PBF LTC2445IUHF#TRPBF LTC2445IUHF#TRPBF
Text Version of Document
LTC2444/LTC2445/ LTC2448/LTC2449
applicaTions inForMaTion
4.5V TO 5.5V 1µF 28 2 VCC BUSY LTC2448 LTC1799 R 29 35 SET REFERENCE REF+ fO OUT V+ VOLTAGE 30 38 0.1V TO V 0.1µF CC REF– SCK 8 37 ANALOG INPUT 3-WIRE CH0 SDO GND –0.5V SPI INTERFACE REF TO 9 36 0.5VREF CH1 CS • • 1,4,5,6,31,32,33,39 • 3 GND EXT NC DIV SET 2444589 F17
Figure 17. Simple External Clock Source
and rejection characteristics. The digital filter’s response
Maximum Conversion Rate
can be adjusted by setting the oversample ratio (OSR) The maximum conversion rate is the fastest possible rate through the SPI interface or by supplying an external at which conversions can be performed. conversion clock to the FO pin. Table 8 lists the properties of the LTC2444/LTC2445/
First Notch Frequency
LTC2448/LTC2449 with various combinations of overs- This is the first notch in the SINC4 portion of the digital filter ample ratio and clock frequency. Understanding these and depends on the F properties is the key to fine tuning the characteristics of the O clock frequency and the oversample ratio. Rejection at this frequency and its multiples (up to LTC2444/LTC2445/LTC2448/LTC2449 to the application. the modulator sample rate of 1.8MHz) exceeds 120dB. This is 8 times the maximum conversion rate.
Table 8. Performance vs Oversample Ratio ENOB MAXIMUM CONVERSION FIRST NOTCH EFFECTIVE –3dB POINT (Hz) OVER- *RMS *RMS (VREF = 5V) RATE (sps) FREQUENCY (Hz) NOISE BW (Hz) SAMPLE NOISE NOISE External fO External fO Internal RATIO LTC2444/ LTC2445/ LTC2444 LTC2445/ Internal (1X Mode) (2X Mode) Internal External fO 9MHz External fO Internal External fO (OSR) LTC2448 LTC2449 LTC2449 LTC2449 Clock [fO/x] [fO/x] Clock [fO/x] Clock [fO/x] Clock [fO/x]
64 23µV 23µV 17 17 2816.35 fø/2738 fo/1458 28125 fo/320 3148 fo/2860 1696 fo/5310 128 4.5µV 3.5µV 20.1 20 1455.49 fo/5298 fo/2738 14062.5 fo/640 1574 fo/5720 848 fo/10600 256 2.8µV 2µV 20.8 21.3 740.18 fo/10418 fo/5298 7031.3 fo/1280 787 fo/11440 424 fo/21200 512 2µV 1.4µV 21.3 21.8 373.28 fo/20658 fo/10418 3515.6 fo/2560 394 fo/22840 212 fo/42500 1024 1.4µV 1µV 21.8 22.4 187.45 fo/41138 fo/20658 1757.8 fo/5120 197 fo/45690 106 fo/84900 2048 1.1µV 750nV 22.1 22.9 93.93 fo/82098 fo/41138 878.9 fo/10200 98.4 fo/91460 53 fo/170000 4096 720nV 510nV 22.7 23.4 47.01 fo/164018 fo/82098 439.5 fo/20500 49.2 fo/183000 26.5 fo/340000 8192 530nV 375nV 23.2 24 23.52 fo/327858 fo/164018 219.7 fo/41000 24.6 fo/366000 13.2 fo/679000 16384 350nV 250nV 23.8 24.4 11.76 fo/655538 fo/327858 109.9 fo/81900 12.4 fo/731000 6.6 fo/1358000 32768 280nV 200nV 24.1 24.6 5.88 fo/1310898 fo/655538 54.9 fo/163800 6.2 fo/1463000 3.3 fo/2717000 *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. 2444589fc 26 For more information www.linear.com/LTC2444 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Analog Input and Reference Digital Inputs and Digital Outputs Power Requirements Timing Characteristics Pin Functions Functional Block Diagram Test Circuit Applications Information Package Description Revision History Typical Application Related Parts
applicaTions inForMaTion
4.5V TO 5.5V 1µF 28 2 VCC BUSY LTC2448 LTC1799 R 29 35 SET REFERENCE REF+ fO OUT V+ VOLTAGE 30 38 0.1V TO V 0.1µF CC REF– SCK 8 37 ANALOG INPUT 3-WIRE CH0 SDO GND –0.5V SPI INTERFACE REF TO 9 36 0.5VREF CH1 CS • • 1,4,5,6,31,32,33,39 • 3 GND EXT NC DIV SET 2444589 F17
Figure 17. Simple External Clock Source
and rejection characteristics. The digital filter’s response
Maximum Conversion Rate
can be adjusted by setting the oversample ratio (OSR) The maximum conversion rate is the fastest possible rate through the SPI interface or by supplying an external at which conversions can be performed. conversion clock to the FO pin. Table 8 lists the properties of the LTC2444/LTC2445/
First Notch Frequency
LTC2448/LTC2449 with various combinations of overs- This is the first notch in the SINC4 portion of the digital filter ample ratio and clock frequency. Understanding these and depends on the F properties is the key to fine tuning the characteristics of the O clock frequency and the oversample ratio. Rejection at this frequency and its multiples (up to LTC2444/LTC2445/LTC2448/LTC2449 to the application. the modulator sample rate of 1.8MHz) exceeds 120dB. This is 8 times the maximum conversion rate.
Table 8. Performance vs Oversample Ratio ENOB MAXIMUM CONVERSION FIRST NOTCH EFFECTIVE –3dB POINT (Hz) OVER- *RMS *RMS (VREF = 5V) RATE (sps) FREQUENCY (Hz) NOISE BW (Hz) SAMPLE NOISE NOISE External fO External fO Internal RATIO LTC2444/ LTC2445/ LTC2444 LTC2445/ Internal (1X Mode) (2X Mode) Internal External fO 9MHz External fO Internal External fO (OSR) LTC2448 LTC2449 LTC2449 LTC2449 Clock [fO/x] [fO/x] Clock [fO/x] Clock [fO/x] Clock [fO/x]
64 23µV 23µV 17 17 2816.35 fø/2738 fo/1458 28125 fo/320 3148 fo/2860 1696 fo/5310 128 4.5µV 3.5µV 20.1 20 1455.49 fo/5298 fo/2738 14062.5 fo/640 1574 fo/5720 848 fo/10600 256 2.8µV 2µV 20.8 21.3 740.18 fo/10418 fo/5298 7031.3 fo/1280 787 fo/11440 424 fo/21200 512 2µV 1.4µV 21.3 21.8 373.28 fo/20658 fo/10418 3515.6 fo/2560 394 fo/22840 212 fo/42500 1024 1.4µV 1µV 21.8 22.4 187.45 fo/41138 fo/20658 1757.8 fo/5120 197 fo/45690 106 fo/84900 2048 1.1µV 750nV 22.1 22.9 93.93 fo/82098 fo/41138 878.9 fo/10200 98.4 fo/91460 53 fo/170000 4096 720nV 510nV 22.7 23.4 47.01 fo/164018 fo/82098 439.5 fo/20500 49.2 fo/183000 26.5 fo/340000 8192 530nV 375nV 23.2 24 23.52 fo/327858 fo/164018 219.7 fo/41000 24.6 fo/366000 13.2 fo/679000 16384 350nV 250nV 23.8 24.4 11.76 fo/655538 fo/327858 109.9 fo/81900 12.4 fo/731000 6.6 fo/1358000 32768 280nV 200nV 24.1 24.6 5.88 fo/1310898 fo/655538 54.9 fo/163800 6.2 fo/1463000 3.3 fo/2717000 *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. 2444589fc 26 For more information www.linear.com/LTC2444 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Analog Input and Reference Digital Inputs and Digital Outputs Power Requirements Timing Characteristics Pin Functions Functional Block Diagram Test Circuit Applications Information Package Description Revision History Typical Application Related Parts
