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How is VCC measured?
Determine the voltage drop between the collector and emitter junctions (Vce) of the transistor using the formula Vce = Vcc – IcRc, where “Vce” is the collector emitter voltage; “Vcc” is the supply voltage; and “IcRc” is the voltage drop across the base resistor (Rb). Determine the Vcc in a feedback-biased circuit.
How do you calculate VRC?
Vrc = Vb [Rc/Re]. This final equation gives us an easy definition for the voltage across the collector resistor that is independent of the beta (current gain) of the transistor, characteristic that varies widely among even the same batch of transistor, and that also depends on the temperature of the transistor.
Can a power supply change the reference voltage of an ADC?
This can cause inaccuracy, for example, if the MCU accepts 3.3 V analog inputs to the internal ADC while the V REF for that internal ADC is actually the supply voltage to the MCU or 5V. In the end, the power supply, which can reasonably vary by as much as 3%, can cause a fairly significant change to conversion results.
How is the reference device related to the ADC?
The voltage reference is external to the ADC, and along with an amplifier to drive the reference, contributes to the overall system noise. Figure 1: Both the voltage reference device and the amplifier (reference buffer) can contribute to overall system noise for the ADC. (Source: e2e.ti.com)
What is the reference voltage for a 10-bit ADC?
The value produced by a 10-bit ADC with a 5V reference and a 3.3V analog input signal (where 3.3V is the highest value measured at the input) would be: (V IN x 1,024) /V REF = (3.3 V x 1,024)/5 V = 675.84 However, the result, if V REF were 3.3 V, rather than 5 V, would be:
How is the output code of an ADC read?
In most cases, the ADC code is read by a microcontroller in 8-bit segments and concatenated into a 32-bit data type. If the ADC’s resolution is less than 32 bits and the output code is signed, the data will need to be sign-extended into the 32-bit integer data type to preserve the sign. The code in Figure 3 shows an example of this operation.