 |
Zakładka z wyszukiwarką danych komponentów |
|
|
Zakładka z wyszukiwarką danych komponentów |
|
AD7877 Arkusz danych(PDF) 20 Page - Analog Devices |
|
||||||||||||||||||||||||||||||
AD7877 Arkusz danych(HTML) 20 Page - Analog Devices |
|
|
20 / 46 page  Data Sheet AD7877 AUXILIARY INPUTS The AD7877 has three auxiliary analog inputs, AUX1 to AUX3. These channels have a full-scale input range from 0 V to VREF. The ADC channel addresses for AUX1 to AUX3 are 0011b, 0100b, and 0101b, and the results are stored in Register 10011b, Register 10100b, and Register 10101b. These pins can also be reconfigured as general-purpose logic inputs/outputs, as described in the GPIO Configuration section. LIMIT COMPARISON The AUX1 measurement, the two battery measurements, and the TEMP1 measurement can all be compared with high and low limits, and an out-of-limit result that generates an alarm output at the ALERT pin. The limits are stored in registers with addresses from 00100b to 01011b. After a measurement from any one of the four channels is converted, it is compared with the corresponding high and low limits. An out-of-limit result sets one of the status bits in the alert status/enable register. For details on these and other registers, see the Register Maps and Detailed Register Descriptions sections. For details on writing and reading data, see the Serial Interface section. As described in the Single Conversion Method section, the temperature comparison is made using the result of the TEMP1 measurement, that is, the diode forward voltage. Because the temperature coefficient of the diode is known but the actual forward voltage can have a wide tolerance, it is not possible to program the high and low limit registers with predeter- mined values. Instead, it is necessary to calibrate the temperature measure- ment, calculate the TEMP1 readings at the high and low limit temperatures, and then program those values into the limit registers, as follows: 1. Calculate LSB per degree = −2.1 mV/(VREF/4096). 2. Save the calibration reading DCAL at the calibration temperature, TCAL. 3. Subtract TCAL from limit temperatures THIGH and TLOW to get the difference in degrees between the limit temperatures and the calibration temperature. 4. Multiply this value by LSB per degree to obtain the value in LSBs. 5. Add these values to the digital value at the calibration temperature to get the digital high and low limit values. Example: The internal 2.5 V reference is used. 1. THIGH = +65°C and TLOW = −10°C. 2. LSB per degree = −2.1 × 10−3/(2.5/4096) = −3.44. 3. DCAL = 983 decimal at 25°C. 4. DHIGH = (65 − 25) × −3.44 + 983 = 845. 5. DLOW = (−10 − 25) × −3.44 + 983 = 1103. Rev. E | Page 19 of 45 |
Podobny numer części - AD7877_17 |
|
Podobny opis - AD7877_17 |
|
|
Link URL |
| Polityka prywatności |
| ALLDATASHEET.PL |
| Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Polish ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
