11/01/05

9

ES51981

3 1/2 AUTO DMM

1.6 Auto power off

ES51981 has a default auto power off function. If the meter idles for more than 10

minutes, the chip automatically turns the power off. When this happens, the state of the

meter is saved. In order to disable auto power off function, power on the meter when

any of the push function, except for HOLD, is pressed down. In addition, when RS232

output is active, the auto power-off function is also disabled. The APO sign on the LCD

panel indicates whether the auto power-off is enabled or not.

Note: Powering on the meter while pressing HOLD turns on all LCD segment until

HOLD is pressed again.

1.7 Sleep

The meter enters sleep mode after auto power off. The SLEEP pin asserts low (-3V) in

the sleep mode, and asserts high (+3V, not 0V) after re-power on.

1.8 Re-power on

After auto power-off, pushing any of the push function or changing the rotary mode can

turn on the meter again. If the meter is re-powered on by changing the rotary mode, the

saved state is cleared. If the meter is re-powered on by push functions, the chip restores

the saved state and enters HOLD mode. The LCD displays the saved value.

2. Measurement Mode Switching

Measurement mode depends on the logic level of FC1, FC2, FC3, FC4, FC5, and KEY.

When FC5 is HIGH, the measurement modes are listed in the following table.

SLACDC FC1

FC2

FC3

FC4

Mode

Function of KEY

0

1

0

1

1

Voltage Measurement

DCV(initial) ↔ACV

0

1

1

0

1

Current Measurement(µA)

DCA(initial) ↔ACA

0

1

1

1

1

Current Measurement(mA)

DCA(initial) ↔ ACA

0

1

0

0

1

Manual Current Measurement(A)

DCA (initial) ↔ACA

0

0

0

0

0

Auto Current Measurement(A)

DCA(initial)

1

1

0

1

1

Voltage Measurement

ACV (initial) ↔DCV

1

1

1

0

1

Current Measurement(µA)

ACA(initial) ↔DCA

1

1

1

1

1

Current Measurement(mA)

ACA (initial) ↔DCA

1

1

0

0

1

Manual Current Measurement(A)

ACA (initial) ↔DCA

1

0

0

0

0

Auto Current Measurement(A)

ACA (initial)

X

0

0

1

1

Resistance Measurement

Ω ↔ Continuity

X

0

1

0

1

Resistance Measurement

Ω ↔ Diode

X

0

0

0

1

Continuity Check

Continuity Diode

X

0

1

1

1

Resistance Measurement

Ω ↔ Continuity ↔Diode

X

0

1

0

0

Temperature(℃)

—

Ps. X means “don’t care”