Ver 1.5

17/03/29

13

ES166

LCR/DMM analog front

2.

Operating Modes

2.1 Voltage Measurement

MCU send write command to select the voltage measurement function. The Hz mode

measurement is available to be enabled with the ACV function (set AC bit to 1)

simultaneously. The measured signal is applied to VR1 terminal (pin75) through 10M

Ω.

See the next table of function command:

F3

F2

F1

F0

AC

Measurement mode

Read data bytes

0

0

0

0

0

DCV mode

D0(12-00)

0

0

0

0

1

ACV+Hz mode

D0(12-00), D1(19-00), D2(19-00)

Note1: D0/D1/D2 all are binary format. SIGN are the sign bit of D0.

Range control for voltage mode (ACV/DCV)

Q2

Q1

Q0

Full Scale Range

Divider Ratio

Resister Connection

0

0

0

6.000V

1/10

VR2 (1.111M

Ω)

0

0

1

60.00V

1/100

VR3 (101k

Ω)

0

1

0

600.0V

1/1000

VR4 (10.01k

Ω)

0

1

1

1000V

1/10000

VR5 (1k

Ω)

1

0

0

600.0mV

1

VR1 (10M

Ω)

Note: For consideration of frequency bandwidth and noise immunity, use ADP1 mode implement mV

range is better.

Frequency range control for ACV+Hz mode

FQ2 FQ1 FQ0

Full Scale Range

0

0

0

N/A

0

0

1

600.0Hz

0

1

0

6.000kHz

0

1

1

60.00kHz

Note: See frequency mode (section 2.6) also. If AC value is less than 1% full scale, the Hz count

should be set to zero by MCU directly.

ALARM bit at voltage mode is used for high crest factor (HCF) signal detection. If

MCU check the ALARM status flag active when data and range are stable, it should

consider the making the existing range up to avoid the signal clamping saturation

caused by HCF signal. There is higher peak voltage with lower RMS value for HCF

signal. So if the range is up according to the ALARM bit, MCU should set the lower

under-limit counts temporarily to avoid the ranging unstable for this case.