1.7 Frequency counter
The time base of the frequency counter is derived from an external crystal oscillator by
4,000,000
Tcounter
=
Fosc
where Fosc is the frequency of the crystal oscillator. Thus, the counter has a 1-second
time base when a 4MHz oscillator is used. The frequency counter can select the proper
range automatically or manually. Auto-range operation extends over six decades, from
1111Hz to 110.00MHz. The following table summarizes the full-scale range of the
frequency counter.
Range
FR112
FR12
FR2
FR3
FR4
Full Scale
11.1 – 111.1Hz
112 – 1111Hz
11.000KHz
110.00KHz
1.1000MHz
11.000MHz
110.00MHz
FR5
FR6
NOTE:
1In the range of FR1, if input frequency is less than 11.1Hz, ES51911 will show 0.0Hz.
2When the reading is more than 111.1Hz, the resolution becomes 1Hz.
1.8 Temperature measurement mode
Temperature measurement mode takes input signal from ADP pin and reference voltage
from (VA+ - VA-). ES51911 has a built-in ℃-to-℉ scale translation circuit, and only
needs an external ℃ scale application circuit. The application circuit for ℉ scale is
not required. In temperature measurement mode, the default range is 1100.0 ℃ or ℉.
VBAR pin is used to control the second decimal point (DP2) on the LCD panel. When
VBAR is LOW, DP2 is turned on and the first decimal point (DP1) is turned off.
v1.2
11
11/09/06
CYRUSTEK [ Cyrustek corporation ]
