Now, all these signals are routed to a multiplexer (IC7), where
three signals are available: the comparator output from Channel
A, the divided-by-16 signal, and the divided-by-1000 signal
from Channel B.
The microcontroller selects one of these signals, depending on
active channel and mode, which is processed to create a
reading.
The analog output from the Power Meter (Channel PWR) is
converted to a digital value by the microcontroller's internal
ADC. This digital value is then used to calculate the power.
Since the Channel B Module uses 3.3V internally, voltage
dividers on the data lines (R17/R19, R23/R20 and R22/R21)
reduce the amplitude from 5V to 3.3V.
The external input (EXT) is protected against overvoltage by
R15 together with D4/D5.
The separately drawn CLK footprint can accept either a
standard crystal oscillator or the optional 1ppm TCXO Module.
R2 is a high power resistor capable of withstanding short
overload events on Channel A/C without damage –
however, it
is important not to exceed the specified maximum limits, as
higher input voltages may damage the frequency counter!
3
Summary of Contents for AE20401
Page 23: ...Finished Component Side Finished Solder Side without the LCD LCD Mounting 17 ...
Page 31: ...Operation Functions Menu Structure 25 ...
Page 37: ...31 Example 1 noise Example 2 one signal superimposed on another ...
Page 50: ...Circuit Diagram Part 1 2 44 ...
Page 51: ...Part 2 2 45 ...
Page 63: ... Nr of valid counts depends on range 57 ...
Page 64: ...ASCEL ELECTRONIC www ascel electronic de 2015 ...