ES278 Datasheet, PDF (10/25 Pages) Cyrustek corporation – 4000 Counts Manual DMM

1.6. Continuity Check
ES278
4000 Counts Manual DMM
Continuity check shares the same configuration with 400.0Ω manual resistance measurement
mode and has buzzer output to indicate continuity. The buzzer generates 2KHz beep and ALARM
(pin 38) drive high output (V+ level) whenever the reading is less than 30Ω. The ES278 built in a
high speed short detection circuit and the detection period could be less than 10ms.
1.7. Diode Measurement
Diode measurement mode shares the same configuration with 4.000V manual voltage measurement
mode and has buzzer output to indicate continuity. The buzzer generates a 2KHz sound and ALARM
(pin 38) drive high output (V+ level) whenever the reading is less than 30mV. The source output
voltage is the same as V+ terminal. If the test circuit is open or the voltage drop between the two
ports of the diode under test is larger than 2V or 2.8V (depends on DIOV pin level), the LCD panel
will show “OL”.
DIOV
DGND/Floating
V-
OL
4.000V
2.800V
1.8. Frequency Counter
The time base of the frequency counter is derived from an external crystal oscillator by
4,000,000
T_counter =
F_osc
Where F_osc 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 400.0Hz to 40.00MHz. The following
table summarizes the Full-Scale range of the frequency counter.
Range
Full Scale
FR1
400.0Hz
FR2
4.000KHz
FR3
40.00KHz
FR4
400.0KHz
FR5
4.000MHz
FR6
40.00MHz
*If input frequency is less than 1.0Hz, ES278 will show 0.0Hz
V 1.5
10
2015/12/11