V 1.1 

10 

2016/08/16 

ES277

4000 Counts DMM

1.6.

Continuity Check

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 ES277 is 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

2.000V

2.800V

1.8.

Frequency Counter

The time base of the frequency counter is derived from an external crystal oscillator by

Tcounter =

4,000,000

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 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, ES277 will show 0.0Hz