V 1.2

7

2016/04/27

ES251

2000 Counts DMM

Function Description

1. Operating Modes

1.1.

Semi-auto calibration scheme

ES251 includes DMM & Clamp-on meter features in single chip. DMM manufacturers need the

calibration process in production. The traditional solution needs the variable resistors for calibration

by manual adjustment. ES251 provide another calibration scheme and the most variable resistors

could be ignored. When ES251 is at OFF-state, pull CALEN (pin 75) to V- to active the calibration

scheme after re-power on. A digital controlled voltage output will be active from DACO. When

semi-auto calibration scheme is active, use HOLD (or REL) key to decrease voltage and use

RANGE (or MMX) key to increase the voltage. Decrease the reference voltage means the counts on

display will be increased. Increase the reference voltage means the counts on display will be

decreased. The adjustment step is approximate one count. If coarse adjustment is required, push

HOLD (or REL) and RANGE (or MMX) larger than one second to speed up to approximate 10

counts per second. After calibration process is finished, push HOLD (or REL) and RANGE (or

MMX) simultaneously less than 1 second to save the digital controlled code to external EEPROM

(24LC02).

The semi-auto calibration scheme supports the following eleven measurement modes. When CALEN

pin is active, set the proper function switches or push KEY to choose the target measurement mode.

When mode is selected, the LCD segment of Unit at related measurement will be blinking.