Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
ADS1100A0IDBVR Datasheet(PDF) 7 Page - Texas Instruments |
|
|
ADS1100A0IDBVR Datasheet(HTML) 7 Page - Texas Instruments |
7 / 23 page ADS1100 7 SBAS239B www.ti.com CLOCK GENERATOR The ADS1100 features an onboard clock generator, which drives the operation of the modulator and digital filter. The Typical Characteristics show varieties in data rate over supply voltage and temperature. It is not possible to operate the ADS1100 with an external modulator clock. INPUT IMPEDANCE The ADS1100 uses a switched-capacitor input stage. To external circuitry, it looks roughly like a resistance. The resistance value depends on the capacitor values and the rate at which they are switched. The switching frequency is the same as the modulator frequency; the capacitor values depend on the PGA setting. The switching clock is generated by the onboard clock generator, so its frequency, nominally 275kHz, is dependent on supply voltage and temperature. The common-mode and differential input impedances are different. For a gain setting of PGA, the differential input impedance is typically: 2.4M Ω/PGA The common-mode impedance is typically 8M Ω. The typical value of the input impedance often cannot be neglected. Unless the input source has a low impedance, the ADS1100’s input impedance may affect the measurement accu- racy. For sources with high output impedance, buffering may be necessary. Bear in mind, however, that active buffers introduce noise, and also introduce offset and gain errors. All of these factors should be considered in high-accuracy applications. Because the clock generator frequency drifts slightly with temperature, the input impedances will also drift. For many applications, this input impedance drift can be neglected, and the typical impedance values above can be used. ALIASING If frequencies are input to the ADS1100 that exceed half the data rate, aliasing will occur. To prevent aliasing, the input signal must be bandlimited. Some signals are inherently bandlimited. For example, a thermocouple’s output, which has a limited rate of change, may nevertheless contain noise and interference components. These can fold back into the sampling band just as any other signal can. The ADS1100’s digital filter provides some attenuation of high-frequency noise, but the filter’s sinc1 frequency re- sponse cannot completely replace an anti-aliasing filter; some external filtering may still be needed. For many appli- cations, a simple RC filter will suffice. DATA RATE NEGATIVE FULL-SCALE –1LSB ZERO +1LSB POSITIVE FULL-SCALE 8SPS 8000H FFFFH 0000H 0001H 7FFFH 16SPS C000H FFFFH 0000H 0001H 3FFFH 32SPS E000H FFFFH 0000H 0001H 1FFFH 128SPS F800H FFFFH 0000H 0001H 07FFH TABLE II. Output Codes for Different Input Signals. INPUT SIGNAL When designing an input filter circuit, remember to take into account the interaction between the filter network and the input impedance of the ADS1100. USING THE ADS1100 OPERATING MODES The ADS1100 operates in one of two modes: continuous conversion and single conversion. In continuous conversion mode, the ADS1100 continuously performs conversions. Once a conversion has been com- pleted, the ADS1100 places the result in the output register, and immediately begins another conversion. When the ADS1100 is in continuous conversion mode, the ST/BSY bit in the configuration register always reads 1. In single conversion mode, the ADS1100 waits until the ST/BSY bit in the conversion register is set to 1. When this happens, the ADS1100 powers up and performs a single conversion. After the conversion completes, the ADS1100 places the result in the output register, resets the ST/BSY bit to 0 and powers down. Writing a 1 to ST/BSY while a conversion is in progress has no effect. When switching from continuous conversion mode to single conversion mode, the ADS1100 will complete the current conversion, reset the ST/BSY bit to 0 and power down. RESET AND POWER-UP When the ADS1100 powers up, it automatically performs a reset. As part of the reset, the ADS1100 sets all of the bits in the configuration register to their default setting. The ADS1100 responds to the I2C General Call Reset command. When the ADS1100 receives a General Call Reset, it performs an internal reset, exactly as though it had just been powered on. I2C INTERFACE The ADS1100 communicates through an I2C (Inter-Inte- grated Circuit) interface. The I2C interface is a 2-wire open- drain interface supporting multiple devices and masters on a single bus. Devices on the I2C bus only drive the bus lines LOW, by connecting them to ground; they never drive the bus lines HIGH. Instead, the bus wires are pulled HIGH by pull-up resistors, so the bus wires are HIGH when no device is driving them LOW. This way, two devices cannot conflict; if two devices drive the bus simultaneously, there is no driver contention. |
Número de pieza similar - ADS1100A0IDBVR |
|
Descripción similar - ADS1100A0IDBVR |
|
|
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 |