Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
AD637BQ Datasheet(PDF) 8 Page - Analog Devices |
|
AD637BQ Datasheet(HTML) 8 Page - Analog Devices |
8 / 20 page AD637 Rev. K | Page 8 of 20 STANDARD CONNECTION The AD637 is simple to connect for a majority of rms measurements. In the standard rms connection shown in Figure 5, only a single external capacitor is required to set the averaging time constant. In this configuration, the AD637 computes the true rms of any input signal. An averaging error, the magnitude of which is dependent on the value of the averaging capacitor, is present at low frequencies. For example, if the filter capacitor, CAV, is 4 μF, the error is 0.1% at 10 Hz and increases to 1% at 3 Hz. To measure ac signals, the AD637 can be ac-coupled by adding a nonpolar capacitor in series with the input, as shown in Figure 5. 1 25kΩ DEN INPUT BUFF IN BUFF OUT SQUARER/ DIVIDER –VS CS dB OUTPUT 3 COMMON BIAS 2NC 4 OUTPUT OFFSET 4.7kΩ +VS 5 25kΩ 6 7 8 9 10 +VS 11 12 NC 13 14 NC VIN VOUT =VIN2 (OPTIONAL) CAV + AD637 ABSOLUTE VALUE –VS +VS CAV VIN Figure 5. Standard RMS Connection The performance of the AD637 is tolerant of minor variations in the power supply voltages; however, if the supplies used exhibit a considerable amount of high frequency ripple, it is advisable to bypass both supplies to ground through a 0.1 μF ceramic disc capacitor placed as close to the device as possible. The output signal range of the AD637 is a function of the supply voltages, as shown in Figure 6. The output signal can be used buffered or nonbuffered, depending on the characteristics of the load. If no buffer is needed, tie the buffer input (Pin 1) to common. The output of the AD637 is capable of driving 5 mA into a 2 kΩ load without degrading the accuracy of the device. 20 15 0 0 10 5 SUPPLY VOLTAGE – DUAL SUPPLY (V) ±3 ±5 ±10 ±15 ±18 Figure 6. Maximum VOUT vs. Supply Voltage CHIP SELECT The AD637 includes a chip select feature that allows the user to decrease the quiescent current of the device from 2.2 mA to 350 μA. This is done by driving CS, Pin 5, to below 0.2 V dc. Under these conditions, the output goes into a high impedance state. In addition to reducing the power consumption, the outputs of multiple devices can be connected in parallel to form a wide bandwidth rms multiplexer. Tie Pin 5 high to disable the chip select. OPTIONAL TRIMS FOR HIGH ACCURACY The AD637 includes provisions for trimming out output offset and scale factor errors resulting in significant reduction in the maximum total error, as shown in Figure 7. The residual error is due to a nontrimmable input offset in the absolute value circuit and the irreducible nonlinearity of the device. Referring to Figure 8, the trimming process is as follows: • Offset trim: Ground the input signal (V IN ) and adjust R1 to give 0 V output from Pin 9. Alternatively, R1 can be adjusted to give the correct output with the lowest expected value of VIN. • Scale factor trim: Resistor R4 is inserted in series with the input to lower the range of the scale factor. Connect the desired full-scale input to VIN, using either a dc or a calibrated ac signal, and trim Resistor R3 to give the correct output at Pin 9 (that is, 1 V dc at the input results in a dc output voltage of l.000 V dc). A 2 V p-p sine wave input yields 0.707 V dc at the output. Remaining errors are due to the nonlinearity. |
Número de pieza similar - AD637BQ |
|
Descripción similar - AD637BQ |
|
|
Enlace URL |
Política de Privacidad |
ALLDATASHEET.ES |
¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | Lista de Fabricantes 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 |