MC33774A Measurement

[mohanagv]

From the MC33774A Datasheet it is given that

The synchronous measurement cycle starts with the next periodic measurement. ADC2B measures the cells continuously until the number of samples for one period is reached.

1.What does one period represents ?

2.Is cycles given in the picture and periods both are same?

3.Is synchronous measurement  is continuous once after .SYNCCYC bit is set or it s required to set the bit again?

[TomasVaverka]

Hi,

1. Please refer to Table 16 which specifies the measurement frequency => period.

2. No, period refers to a broader time frame that encompasses cycles.

3. it s required to set the bit again.

BRs, Tomas

[mohanagv]

In MC33774A Data sheet it is given that for synchronous measurement

ADC2B measures one signal several times before it switches to the next signal. In a synchronous measurement cycle, the signal is measured for SECM_PER_CTRL.PERLEN × 14 × ts(meas).

If SECM_PER_CTRL.PERLEN is set to 16 and ts(meas) is 17 µs, is the expected time to measure 1 VB signal calculated as 16 × 14 × 17 = 3.808 ms?

we are assuming that one cycle in the picture is equal to 16 scans (i,e 3.808ms)

[TomasVaverka]

Hi, 

Basically it is like this:

Within a SCAN is a single measurement of a voltage.

This single measurement is not made available, only the averaged value.

With PERLEN one can define how long the averaging shall last (16 to 511 samples). 

A new measurement CYCLE is started each time a new measurement result is made available = SCAN_time * PERLEN.

The AN12913 provides additional info about the measurement.

BRs, Tomas