1
2V+PPositive supply voltage, output of on-chip DC-DC converter.
3V+PPositive supply voltage, output of on-chip DC-DC converter.
4NC
5CL+IOHigh resolution positive connection for reference capacitor.
6CL-IOHigh resolution negative connection for reference capacitor.
7CILOHigh resolution integrator output. Connected to integral capacitor
8CAZLOHigh resolution auto-zero capacitor connection.
9BUFLOIntegral resistor connection for high resolution buffer output
10IVSHIHigh current measurement input.
11IVSLILow current measurement input
12OVXIInput high voltage for resistance measurement
13OVHIOutput connection for resistance measurement
14OVSGISense low voltage for resistance measurement
15NC
16OR1OReference resistor connection for 399.9Ω range
17VR5OVoltage measurement ÷10000 attenuator(2000V)
18VR4OVoltage measurement ÷1000 attenuator(200.0V)
19VR3OVoltage measurement ÷100 attenuator(20.00V)
20VR2OVoltage measurement ÷10 attenuator(2.000V)
21TEST 5I/OTest pin
22ACVLONegative output of AC to DC converter
23ACVHOPositive output of AC to DC converter.
24NC
25ADIINegative input of internal AC to DC Opamp.
26NC
27ADOOOutput of internal AC to DC Opamp.
28NC
29VRHOOutput of band-gap voltage reference .Typically –1.2V
30VRIReference input voltage connection. Typically –100mV
31VA+IFor ADP. Deintegrating voltage positive input. The input should
32VA-For ADP. Deintegrating voltage negative input. The input should
33ADPIADP input
34SGNDGSignal Ground
35VR1IMeasurement input
36NC
37VBARIDecimal point control for temperature measurement in ADP mode.
38NC
39NC
40NC
41NC
42SLEEPOAsserts low in the sleep mode. See page 8, function description
43NC
44NC
45RS232IPulse low to enable serial data output.
46BKLITIBack light function. Pulse low to set BKOUT pin output
47~50
Continued on next page…….
NC
SEG16~SEG13
be higher than VA-.
be lower than VA+.
OLCD segment line 16~13
Description
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3 1/2 AUTO DMM
…continued from previous page
51
52
53~64
65BP4OLCD backplane 4
66BP3OLCD backplane 3
67BP2OLCD backplane 2
68BP1OLCD backplane 1
69ANNUNCOSquare wave output at the backplane frequency, synchronized to
70NC
71BUZINIEnables the buzzer. Low active.
72BUZOUTOOutputs an 2KHz audio frequency signal for driving piezoelectric
73NC
74OSC2OCrystal oscillator output connection
75OSC1ICrystal oscillator input connection
76NC
77XTALIThe chip uses internal RC oscillator if pin is connected to V-, and
78NC
79BKOUTOIf BKLIT function is enabled, this pin will change from –3V to +3V
80NC
81HOLDIPulse low to enable HOLD mode.
82RANGEIPulse low to enable manual mode and manual range selection.
83SLACDCISelect AC/DC initial state. This pin is pull low
84KEYIPulse low to change mode. In ADP mode, if this pin is connected to
85FC5ISwitch 5 for function selection.
86FC4ISwitch 4 for function selection.
87FC3ISwitch 3 for function selection.
88FC2ISwitch 2 for function selection.
89FC1ISwitch 1 for function selection.
90NC
91C+OPositive capacitor connection for on-chip DC-DC converter.
92C-ONegative capacitor connection for on-chip DC-DC converter.
93NC
94SDOORS232 compliant serial data output.
95LBAT9ILow battery configuration. If 3V battery is used, connect it to AGND
96V-PNegative supply voltage. Connecting to battery negative terminal.
97V-PNegative supply voltage. Connecting to battery negative terminal.
98DGNDGDigital ground, connected to battery positive terminal.
99AGNDGAnalog ground.
100AGNDGAnalog ground.
NC
NC
SEG12~SEG01
OLCD segment line 12~01
BP1. ANNUNC can be used to control display annunciator. Connect an LCD segment to ANNUNC to turn it on; connect an LCD
segment to its backplane to turn it off.
buzzer when BUZIN is low.
uses external crystal oscillator if this pin is floating or connected to
DGND
for 60 sec, once press BKLIT pin again within 60 sec, this pin will
change back to –3V.
V-, the buzzer output will be off when the ADP input overflows.
The default low-battery threshold voltage is –2.3V. If 9V battery is
used, the low battery annunciator is displayed when the voltage of
this pin is less than VRH (-1.2V)
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A
V
A
D
P
n
ES51981
3 1/2 AUTO DMM
Absolute Maximum Ratings
CharacteristicRating
Supply Voltage (V- to AGND)-4V
nalog Input VoltageV- -0.6 to V+ +0.6
+
GND/DGND
igital InputV- -0.6 to DGND +0.6
ower Dissipation. Flat Package500mW
Operating Temperature
Storage Temperature
Electrical Characteristics
ParameterSymbolTest ConditionMin.Typ.MaxUnits
Power supplyV--3.5-3.0-2.2V
I
TC
I
DD
SS
REF
RF
In DCV mode
Voltage roll-over errorREV
Voltage nonlinearityNLV
Input Leakage-10110PA
Low battery flag voltageV- to AGND-2.5-2.3-2.1V
Zero input reading10MΩ input resistor-000000+000counts
Reference voltage and open circuit
Voltage for 200Ω measurementV
Peak to peak backplane
Drive voltage
Counter time base periodf
Open circuit voltage for Ω
Measurement (except 200Ω)
Internal pull-high to 0V
Current
Internal pull-low to VCurrent
AC frequency response at
2.000V range
Reference voltage temperature
Coefficient
V+
≥ (AGND/DGND+0.5V)
AGND/DGND
0℃ to 70℃
-25℃ to 125℃
Normal operation
In sleep mode
resistor
Best case straight
line
100KΩ resistor
between VRH and
AGND
-3.5V
≤ V ≤-2.2V
= 4MHZ
OSC
Ω and Continuity
Mode
Between V- pin and
HOLD, RANGE,
KEY, FC1, FC2,
FC3, FC4, FC5,
XTAL, BKLIT
Between V- pin
and RS232
Between GND Pi
and SLACDC
±1%
±5%
100KΩ resister
Between VRH
0℃<TA<70℃
≥ (V- -0.5V)
TA=2 5℃, V- = -3V
—
—
——
——
-1.3-1.2-1.1V
3.003.23.40V
—
-0.54-0.47-0.4V
—
—
—
—
—
0.91.1mAOperating supply current
0.15µA
±0.1%F.S10MΩ input
±0.1%F.S
1
1.2
11
1.5µA
40-400
400-2000
50
—
—
—
—
—
—ppm/℃
sec
µA
HZ
Note
:
1. Full Scale
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ES51981
3 1/2 AUTO DMM
Function Description
1. Operating Modes
1.1 Voltage Measurement
A reconfigurable voltage divider automatically provides a suitable range in voltage
measurement mode. The following table summarizes the full scale ranges in each
Continuity check shares the same configuration with 200.0Ω manual resistance
measurement mode, but with buzzer output to indicate continuity. The buzzer generates a
2KHz sound whenever the digit number less than 25Ω. Because the cycle time of
measurement is only 50ms, the least significant digit will not display.
1.5 Diode Measurement
Diode measurement mode shares the same configuration with 2.000V manual voltage
measurement mode. If the test circuit is open or the voltage drop between the two ports
of the device (diode) under test is larger than 2V, the LCD panel will show “OL”. The
buzzer generates a 2KHz sound whenever the digit number is less than 0.25V. Because
the cycle time of measurement is only 50ms, the least significant digit will not display.
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
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ES51981
3 1/2 AUTO DMM
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 FC1FC2FC3FC4ModeFunction of KEY
0 1011 Voltage Measurement
0 1101Current Measurement(µA)
0 1111Current Measurement(mA)
0 1001
0 0000Auto Current Measurement(A)DCA(initial)
1 1011 Voltage Measurement
1 1101Current Measurement(µA)
1 1111Current Measurement(mA)
1 1001
1 0000Auto Current Measurement(A)ACA (initial)
X 0011Resistance Measurement Ω ↔ Continuity
X 0101Resistance MeasurementΩ ↔ Diode
X 0001Continuity CheckContinuity Diode
X 0111Resistance MeasurementΩ ↔ Continuity ↔Diode
X 0100
Manual Current Measurement(A)
Manual Current Measurement(A)
Temperature(℃)
DCV(initial)
DCA(initial)
DCA(initial)
DCA (initial) ↔ACA
ACV (initial)
ACA(initial)
ACA (initial)
ACA (initial) ↔DCA
↔ACV
↔ACA
↔ ACA
↔DCV
↔DCA
↔DCA
—
Ps. X means “don’t care”
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)
ES51981
3 1/2 AUTO DMM
When FC5 is LOW, KEY is disable. The corresponding measurement modes are list
below
SLACDC FC1FC2FC3FC4Mode
0 1011AC Voltage Measurement
0 1101AC Current Measurement(µA)
0 1111AC Current Measurement(mA
0 1001
0 0000
1 1011DC Voltage Measurement
1 1101DC Current Measurement(µA)
1 1111DC Current Measurement(mA
1 1001
1 0000
X 0011Resistance Measurement
X 0101Resistance Measurement
X 0001Continuity Check
X 0111diode Measurement
X 0100
Manual AC Current Measurement(A)
Auto AC Current Measurement(A)
Manual DC Current Measurement(A)
Auto DC Current Measurement(A)
Temperature(℉)
Ps. X means “don’t care”
The other combinations of FC1, FC2, FC3, and FC4 are for ADP modes. In ADP modes
, if FC5 is LOW, the minus sign on the LCD panel will not be displayed. And if KEY pin
is floating, the buzzer beeps when the input signal is overflow. The ADP mode function
is summarized below.
FC1FC2FC3FC4Mode
1110ADP0
1100ADP1
1000ADP2
1010ADP3
Note: Temperature measurement mode takes input signal from ADP pin. In temperature
measurement mode, VBAR pin is used to control the right most digit point on the
LCD panel. When VBAR is LOW, this digit point is displayed.
3. Push function
3.1 HOLD
HOLD mode makes the meter stop updating the LCD panel. This mode can be nested in
most of the special modes. Enabling HOLD function in automatic mode makes the
meter switch to manual mode, but the full scale range remains the same. HOLD function
can be cancelled by changing the measurement mode, pressing RANGE, or push HOLD
again.
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3 1/2 AUTO DMM
3.2 Range
RANGE pin switches to and from automatic and manual mode, and while in manual
mode, changes the full scale range. The following figure shows the state transition.
1 push < 1 sec
Automatic
Mode
1 push > 1 sec
Measurement ModeAutoManualControl RangeInitial Range
V(DC/AC)VR2 – VR5
µA(DC/AC)R1 – R2
mA
(AC/DC)
Auto A(DC/AC)R1 – R2
A(DC/AC)fixedfixed20.00A20.00A
ΩOR1- OR6
Continuityfixedfixed200.0Ω200.0Ω
DiodeFixedfixed2.000V2.000V
R1-R2R1 → R2
VRi →
VRi + 1,
VR5 → VR1
R1 → R2,
R2 → R1
R2 → R1
R1 → R2,
R2 → R1
ORi →
ORi + 1,
OR6 → OR1
Note: Pushing RANGE resets all existing special modes.
Manual
Mode
1
ush < 1 sec
200.0mV – 2000V2.000V
200.0µA - 2000µA200.0µA
20.00mA –
200.0mA
2.000A – 20.00A2.000A
200.0Ω – 20.00MΩ 200.0Ω
Range up
20.00mA
3.3 KEY
See Section “Measurement Mode Switching” for the function of this pin.
4. Serial Data Output
The serial data sent to SDO pin twice every A/D conversion cycle. The data format
complies with JIS 7Bits transmission code with a baud rate of 19230. The host can use
RS232 interface to read the data. A single data packet includes a start bit (always 0), 7
data bits, an odd parity check bit, and a stop bit (always 1). The high and low voltage
levels correspond to DGND and V- respectively. SDO remains at 1 (high) when it is
inactive. Hence the start bit (0) could be used as the triggering signal to begin the
reading process. The following figure shows the data format of a single packet. The
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LSB is sent first and the MSB is sent last.
single package
ES51981
3 1/2 AUTO DMM
0V
-3V
0
D0 ~D6
p
1P
LSBMSB
One data block consists of 11 packets, or 110 bits. The following figure shows the
format of a data block. The range packet indicates the full scale range of the meter.
Digit 3 through digit 0 are just the digits on the LCD panel. The function packet
indicates the measurement mode of the meter. Status, option 1 and option 2 give the
status of the meter. CR and LF are delimiters used to separate the blocks.
All package
0
range
0
p
1
0
p
1 0
p
1 0
digit2digit3
p
1 0
p
1
p
1
digit0digit1
0
status
0
CR LF
The meter always outputs the current input value to the serial port in spite of HOLD
mode. Each block is repeated twice in one conversion cycle. The detailed data format of
each packet is listed below.
p
1 0
option1
p
1 0
p
1 0
p
1
function
option2
p
1
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3 1/2 AUTO DMM
4.1 FUNCTUON
This packet indicates the measurement mode of the meter. The following table
summarizes the transmitted code for each mode. Note that the encoding of this packet is
different from the encoding of FC1-FC4 switch.
CodeMeasurement Mode
0111011Voltage
0111101µA Current
0111111mA Current
0110000Auto A current
0111001 Manual A Current
0110011
Because the cycle time of measurement for continuity/diode mode is only 50ms, the
least significant digit may not be accurate.
4.4 STATUS
The format of this shown below. The Judge field is meaningful only when the Function
packet indicates Temperature mode. In Temperature mode, judge is 1 if the unit is ℃
and is 0 of the unit is ℉ . Sign field indicates whether the minus sign on the LCD
panel is on or off. BATT field is one of battery low condition is true. OL indicates input
overflow.
011JudgeSignBATTOL
BIT 6BIT 5BIT 4BIT 3BIT 2BIT1BIT 0
4.5 OPTION 1
This packet is not used.
011HOLD000
BIT 6BIT 5BIT 4BIT 3BIT 2BIT1BIT 0
If Hold field is 1, Hold function is active. Hold function will not influence Digital 3~0
which is related to current measured value.
4.6 OPTION 2
This packet contains information on the operation mode of the meter. The format is
shown below. The DC field indicates that the meter operates in DC measurement mode,
either voltage or current. The AC field indicates that the meter operates in AC
measurement mode, either voltage or current. The AUTO field is set to one if the meter
operates in automatic mode, and is set to zero when the meter operates in manual mode.
011DCACAUTO0
BIT 6BIT 5BIT 4BIT 3BIT 2BIT1BIT 0
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4.7 CR
Carrage return. The transmitted code is 0001101.
4.8 LF
Line feed. The transmitted code is 0001010.
5. Miscellaneous
The conditions which the meter turns on the buzzer include:
(1) Changing measurement mode generates one beep.
(2) Pressing any of the push junctions generates one beep, if the function is valid.
(3) Power on and re-power on generate one beep.
(4) Input overflow in voltage and current mode generates one beep every 0.3 seconds
(or 3.33 beeps per second.)
(5) Continuity(diode) check generates a continuous 2KHz beep whenever the
measurement is less then 25Ω(0.25V)
(6) Auto power off generates a 2KHz beep which lasts for 1.5 seconds.
The following figures shows the output waveform from the BUZOUT pin.
VIn voltage measurement mode, and diode measurement mode.
AIn current measurement mode.
ΩIn resistance measurement mode, and continuity mode.
FIn capacitance measurement mode.
In continuity check mode.
In diode mode.
HzIn frequency mode.
DCIn DC voltage or DC current mode.
ACIn AC voltage or AC current mode.
AUTOWhen automatic full scale range selection is enabled.
MANUIn manual mode.
HOLDWhen HOLD function is enabled.
m1In capacitor measurement mode and the full scale range is in the order of mF.
u1In capacitor measurement mode and the full scale range is in the order of uF.
nIn capacitor measurement mode and the full scale range is in the order of nF.
m2In voltage or current measurement mode and the full scale range is in the order of
u2In current measurement mode and the full scale range id in the order of uA.
MIn resistance measurement mode and the full scale range is in the order of MΩ
KIn resistance measurement mode and the full scale range is in the order of KΩ
℃In temperature measurement mode and when the unit is ℃
℉In temperature measurement mode and when the unit is ℉
APOWhen auto power off function is enabled.
-In voltage or current measurement mode and when the input is negative.
10
-3
.
V- +3.1
V-
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3 1/2 AUTO DMM
5.4 Operating Timing
ES51981 incorporates a dual slope ADC with four phases: ZI, AZ, INT and DINT.
The timing of each phase is listed below.
*Voltage /ohm/ADP measurement:
PhaseTime
ZI100ms
AZ100ms
INT100ms
DINT200ms
Ps. In the voltage and ohm measurement with auto mode, if the range is changed,
the internal clock rate will increase ten times and the new measurement cycle
becomes 1/10 times of the original cycle until the range is stable.