CYRUSTEK ES51921

ES51921
22,000 Counts Auto DMM
• Programmable LCD segment display
Features
• Support low pass filter* for AC voltage & Clamp
• 22,000 counts LCD driver with 46-segment
ACA measurement
bargraph display
• SHIFT function
• Conversion rate : 2 times/s
• High-crest-factor signal detection
• Full automatic measurement
(Taiwan patent no.: 234661)
*Voltage measurement:
• Band-gap reference voltage output
Manual 220.00mV / Auto 2.2000V – 1000.0V /
• CE selection (610V, 1010V or 1500V)
Auto 220.00 – 1000.0V
• Serial data output (RS232 format)
*Current measurement: μA/mA/A
• LCD segment check when power on
*Resistance measurement:
• Auto power off with idle time selection
220.00Ω – 220.00MΩ
• Sleep output
*Capacitance measurement:
• Re-power on
22.000nF – 220.00mF(25sec)
(Taiwan patent no.: 323347,453443)
• On-chip buzzer driver
*Frequency counter
• 3V DC power supply
• Low battery detection for 3V or 9V battery
22.00Hz – 220.00MHz
• Current modes for clamp meter
Description
• Duty cycle measurement (5.0% ~ 94.9%)
ES51921 is an integrated analog-to-digital
converter (ADC) with 22,000 counts LCD
display, automatic range selection, and 3V DC
power supply. Automatic range selection is
provided for voltage (AC/DC) measurement,
resistance measurement, current measurement,
capacitance measurement, and frequency
counter. Expensive and bulky mechanical
range switches are not required. Other features
include relative value display, Zero function,
data holding, maximum and minimum holding,
diode measurement, temperature measurement,
continuity checking, low battery detection,
auto power off, re-power on, and RS232 data
output.
• Diode measurement
• Continuity check
• ADP mode with independent reference voltage
• Temperature mode with internal scale translation
circuit from oC to oF
• Push functions
*Range change function
*VAHZ function
*Relative function
*Zero function in manual DCA mode
*Data hold function with delay hold feature
*MAX/MIN function
*Back-light function
*KEY function
Ver. 3.2
1
10/06/23
*Note: A multimeter with filtered measurement mode is a filed US patent. To avoid the patent infringement, produce a DMM with
low pass filter mode is prohibited to export to USA. Keep pin55 floating could make the LPF mode disable.
ES51921
22,000 Counts Auto DMM
Application
Digital multimeter
Clamp meter
Thermometer
Pin Assignment
Cyrustek.
com.tw
ES51921
Ver. 3.2
2
10/06/23
ES51921
22,000 Counts Auto DMM
Pin Description
Pin No
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
Symbol
V+
V+
DGND
AGND
AGND
CH+
CHCIH
BUFFH
CAZH
CL+
CLCIL
CAZL
BUFFL
RAZ
IVSH
IVSL
OVX
OVH
OVSG
OR1
VR5
VR4
VR3
VR2
TEST5
ACVL
Type
O
O
P/G
P/G
P/G
IO
IO
O
O
O
IO
IO
O
O
O
O
I
I
I
I
O
O
O
O
O
O
IO
O
29
ACVH
O
30
31
32
33
34
35
36
37
38
39
40
41
ADI
ADO
OHMC1
OHMC2
OHMC3
OHMC4
NC
VRH
VR
SGND
ADP
VA+
I
O
O
O
O
O
O
I
G
I
I
42
VA-
I
43
44
45
V220m
VR1
VBAR
I
I
I
46
CA-
IO
Ver. 3.2
Description
Output of on-chip DC-DC converter.
Output of on-chip DC-DC converter.
Digital ground. Connecting to 3V battery positive terminal.
Analog ground.
Analog ground.
Positive connection for reference capacitor of high-speed A/D.
Negative connection for reference capacitor of high-speed A/D.
High-speed integrator output. Connect to integral capacitor.
High-speed buffer output pin. Connect to integral resistor.
High-speed auto-zero capacitor connection.
Positive connection for reference capacitor of high-resolution A/D.
Negative connection for reference capacitor of high- resolution A/D.
High-resolution integrator output. Connect to integral capacitor.
High-resolution auto-zero capacitor connection.
High-resolution Buffer output pin. Connect to integral resistor
Buffer output pin in AZ and ZI phase.
Current measurement input for 2200μA, 220mA and 22A modes.
Current measurement input for 220μA, 22mA.
Input high voltage for resistance measurement
Output connection for resistance measurement
Sense low voltage for resistance measurement
Reference resistor connection for 220.00Ω range
Voltage measurement ÷10000 attenuator(1000.0V)
Voltage measurement ÷1000 attenuator(220.00V)
Voltage measurement ÷100 attenuator(22.000V)
Voltage measurement ÷10 attenuator(2.2000V)
Test pin
DC signal low input in ACV/ACA mode. Connect to negative output
of external AC to DC converter.
DC signal high input in ACV/ACA mode. Connect to positive output
of external AC to DC converter.
Negative input of internal AC to DC OP Amp.
Output of internal AC to DC OP Amp.
Filter capacitor connection for resistance mode.
Filter capacitor connection for resistance mode.
Filter capacitor connection for resistance mode.
Filter capacitor connection for resistance mode.
Output of band-gap voltage reference. Typically –1.23V
Reference input voltage connection. Typically –100mV
Signal Ground.
Measurement input in ADP mode. Connect to AGND if no used.
For ADP mode. De-integrating voltage positive input. The input
should be higher than VA-.
For ADP mode. De-integrating voltage negative input. The input
should be lower than VA+.
Independent input terminal for AC/DC 220.00mV mode.
Measurement Input.
In temperature mode, it is used to control decimal point.
In µA or mA modes, it is used to control the ‘µ’ or ‘m’ sign.
Negative auto-zero capacitor connection for capacitor measurement
3
10/06/23
ES51921
22,000 Counts Auto DMM
47
CA+
48
R9K
49
R1K
50
NC
51
NC
52
LPFC1
53
LPFC2
54
LPFOUT
55
LPFON
56
LPFC3
57
BUZIN
58
SLEEP
59
FREQ
60
NC
61 - 90 SEG31 – SEG01
91
BP4
92
BP3
93
BP2
94
BP1
95
ANNUNC
IO
O
O
Positive auto-zero capacitor connection for capacitor measurement
Connect to a precise 9KΩ resister for capacitor measurement.
Connect to a precise 1KΩ resister for capacitor measurement.
O
O
O
I
I
I
O
I
Capacitor C1 connection for internal low-pass filter
Capacitor C2 connection for internal low-pass filter
Capacitor C1 connection for internal low-pass filter
Pull to V- to enable low-pass filter
Capacitor C3 connection for internal low-pass filter
Pull to V- to enable the BUZOUT.
Sleep mode indicator, asserts low in SLEEP mode.
Frequency counter input, offset V-/2 internally by the chip.
O
O
O
O
O
O
LCD segment line 01 – 31
LCD backplane 4
LCD backplane 3
LCD backplane 2
LCD backplane 1
Square wave output at the backplane frequency, synchronized to BP1.
ANNUNC can be used to control display annunciator. Connect a
LCD segment to ANNUNC to turn it on; connect an LCD segment to
its backplane to turn it off.
Pulse to V- to enable HOLD function.
Pulse to V- to enable manual mode and manual range selection.
Pulse to V- to enable Relative function or Zero function.
Pulse to V- to change mode. In ADP mode, if this pin is connected to
V-, the buzzer output will be off when the ADP input overflows.
Pulse to V- to enable MAX/MIN function.
96
97
98
99
HOLD
RANGE
REL_ZERO
KEY
I
I
I
I
100
101
102
103
104
MAX/MIN
NC
BKLIT
VAHZ
BUZOUT
I
I
I
O
105
BKOUT
O
106
107
108
109
110
OSC2
OSC1
SCLK
SDATA
μPLCD
O
I
I
I
I
111
112
113
114
RS232
APOSEL
BKSEL
VST
I
I
I
I
115
SHIFT
I
116
117
118
119
120
CESEL
SLACDC
FC5
FC4
FC3
I
I
I
I
I
Ver. 3.2
Back light function. Pulse low to set BKOUT pin output.
Pulse to V- to enable VAHZ mode.
Outputs a 2KHz audio frequency signal for driving piezoelectric
buzzer when BUZIN is low.
If BKLIT function is enabled, this pin will change from –3V to +3V
For 60 sec, once press BKLIT pin again within 60 sec, this pin will
Change back to –3V.
Crystal oscillator output connection
Crystal oscillator input connection
Clock signal input for programmable LCD segment display.
Serial data input pin for programmable LCD segment display.
Enable pin for programmable LCD segment display and SDO output
enable
Assert low to enable serial data output.
Idle time selection for auto power off feature.
Set to V- to change the backlight idle time from 60 sec. to 180 sec.
Set to V- to enable the auto range voltage mode to start from 220.00V
range.
Assert low to enable LCD SHIFT future, only works in 220MΩ, and
all capacitor measurement ranges
CE selection feature control pin.
Select initial state.
Switch 5 for function selection.
Switch 4 for function selection.
Switch 3 for function selection.
4
10/06/23
ES51921
22,000 Counts Auto DMM
121
122
123
124
125
126
127
128
FC2
FC1
SDO
C+
CVVLBAT9
I
I
O
O
O
P
P
I
Switch 2 for function selection.
Switch 1 for function selection.
RS232 compliant serial data output.
Positive capacitor connection for on-chip DC-DC converter.
Negative capacitor connection for on-chip DC-DC converter.
Negative supply voltage. Connecting to 3V battery negative terminal.
Negative supply voltage. Connecting to 3V battery negative terminal.
Low battery configuration. If 3V battery is used, connect it to AGND.
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)
Absolute Maximum Ratings
Characteristic
Supply Voltage (V- to AGND)
Analog Input Voltage
V+
AGND/DGND
Digital Input
Power Dissipation. Flat Package
Operating Temperature
Storage Temperature
Rating
-4V
V- -0.6 to V+ +0.6
V+ ≥ (AGND/DGND+0.5V)
AGND/DGND ≥ (V- -0.5V)
V- -0.6 to DGND +0.6
500mW
0℃ to 70℃
-25℃ to 125℃
Electrical Characteristics
TA=25℃, V- = -3V
Parameter
Power supply
Operating supply current
In DCV mode
Voltage roll-over error
Voltage nonlinearity
Symbol
Test Condition
VIDD
Normal operation
In sleep mode
ISS
REV 10MΩ input resistor
Best case straight
NLV
line
Input Leakage
Low battery flag voltage
Zero input reading
Band-gap reference voltage
VREF
Peak to peak backplane
drive voltage
Counter time base period
Internal pull-high to 0V
current
Open circuit voltage for 220Ω
measurement
Ver. 3.2
V- to AGND
10MΩ input resistor
100KΩ resistor
between VRH and
AGND
-3.5V≤ V ≤-2.2V
fOSC = 4MHZ
Between V- pin and
HOLD, RANGE,
KEY, FC1, FC2,
FC3, FC4, FC5,
BKLIT,MAXMIN
Min.
-3.5
—
—
—
Typ.
-3.0
2.0
2.5
—
Max
-2.5
2.5
5
±0.03
Units
V
mA
µA
%F.S1
—
—
±0.03
%F.S
-10
-2.5
-000
1
-2.3
000
10
-2.1
+000
PA
V
counts
-1.3
-1.2
-1.1
V
3.0
3.1
3.2
V
—
1
—
sec
—
1.2
—
µA
Between V- pin
and RS232
—
11
—
220Ω mode
—
-3.0
—
5
V
10/06/23
ES51921
22,000 Counts Auto DMM
Open circuit voltage for Ω
measurement (except 220Ω)
Ω and Continuity
Mode
Internal pull-low to Vcurrent
AC frequency response at 2.2000V
range
Between GND Pin
and SLACDC
±1%
±5%
3rd order LPF
100KΩ resister
Between VRH
0℃<TA<70℃
3dB frequency for LPF mode
Reference voltage temperature
coefficient
TCRF
22nF – 220nF
Capacitance measurement accuracy2
2.2µF
22µF~220mF
-0.58
-0.53
-0.48
V
1.5
—
—
800
µA
40-400
—
400-2000 —
1000
1200
HZ
Hz
—
75
—
ppm/℃
-1.0
-10
-1.0
-10
-2.0
20
—
—
—
—
1.0
10
1.0
10
2.0
20
%
counts
%
counts
%
counts
Note:
1.Full Scale
2.Above specification from 22nF to 2.2uF ranges are specified under REL mode. The
reading is calibrated to zero by relative function, when input is floating.
Function Description
1. Operating Modes
1.1 Voltage Measurement
A re-configurable voltage divider automatically provides a suitable range in voltage
measurement mode. The following table summarizes the full-scale ranges in each
configuration.
Configuration Full Scale Range Divider Ratio Resistor Connection
VR1
220.00mV1
1
VR2
2.2000V
1/10
R2 / (R1+R2)
VR3
22.000V
1/100
R3 / (R1+R3)
VR4
220.00V2
1/1000
R4 / (R1+R4)
VR5
2200.0V
1/10000
R5 / (R1+R5)
Input Pin
V220m V.S. SGND
VR1 V.S. SGND
VR1 V.S. SGND
VR1 V.S. SGND
VR1 V.S. SGND
Note:
1.
220.00mV range is independent and manual mode. The input pin is different from other voltage
ranges.
2.
If VST is set to V- level, the auto range mode will start from 220.00V range. 2.2000V – 22.000V
ranges only exist in manual mode.
Ver. 3.2
6
10/06/23
ES51921
22,000 Counts Auto DMM
1.1.2 CE selection
ES51921 has a CE selection feature archived by configuring a CESEL pin. If pin CESEL is connected to
V-, ES51921 will have a 610.0V overflow level in DCV and ACV ranges. If pin CESEL is connected to
DGND, the overflow level will be set to 1010V. When it is floating, the overflow level is set to 1500V in
DCV mode and 1010V in ACV mode. The meter will show OL when the measuring signal reaches the
overflow level. The configuration of CESEL is listed below.
CESEL
VDGND
Floating
DCV
610.0
1010.0V
1500.0V
ACV
610.0V
1010.0V
1010.0V
1.1.3 HCF signal detection
ES51921 provides detection of high-crest-factor (HCF) signal in ACV mode. When this
function is enabled, ES51921 senses the signal and determines it as HCF if the Vpp is
large enough. Once the signal is determined as HCF, ES51921 will jump up one
measuring range regardless of current measurement value. It takes 60ms to jump one
range up. The jumping up process will continue until the maximum range is reached.
With HCF detection, a more accurate result could be obtained. For example, when a
input signal with Vpeak=240V, Vrms=40V(CF=6) was applied, traditional DMMs
might stay at 22.000V range but shows counts with the amount of error up to 10% or
even bigger. The error rises from limited input/output swing at internal ADC. With HCF
detection, DMM will stay at 220.00V and exhibits more accurate results.
In addition to accuracy improvement, HCF will speed up the measuring process for
high voltage signals. For example, a 500Vrms is applied, ES51921 will take about
180ms (3 HCF jumps) to enter 1000.0 V range. And it takes 1 or 2 measuring processes
to obtain the stable result. Thus a stable LCD reading could be obtained within 1 sec.
Ver. 3.2
7
10/06/23
ES51921
22,000 Counts Auto DMM
1.1.4 The true RMS-to-DC conversion with ES636
If ES636 is used for true RMS-to-DC measurement, the test circuit is shown in Figure 1.
Make ADO and ADI pin short, and TEST5 pin keeps float. Connect OVSG pin to
AGND through a switch in ACV measurement mode. If the DCV and ACV
measurement modes are in the same rotary switch, please also add this switch in the
rotary switch. The configuration of this switch will not influence the precision of DCV
measurement.
2.2u
+
-Vs
10u
1
2
3
4
5
6
7
ES636
+
100
1K
10K
101K
1.111M
+Vs
14
13
12
11
10 150
9
8
100K
+Vs
OVSG
OR1
VR5
VR4
VR3
VR2
TEST5
ACVL
ES51921
ACV
ACVH
500K
2.2u
+
20k
-Vs
ADI
ADO
AGND
1k
Figure 1. The true RMS-to-DC conversion with ES636
Ver. 3.2
8
10/06/23
ES51921
22,000 Counts Auto DMM
1.1.5 Low-pass filter feature
ES51921 provides a 3-order low-pass filter to reduce the influence of high frequency
noise above 1KHz(3dB). This LPF feature is available in all ACV or clamp_meter
ACA modes. Set FC5 to low in these mode, the KEY bottom is use to activate the LPF
feature. Press KEY bottom for less than 1 second force meter enter LPF mode, and the
AC sign on LCD panel will blink until the LPF mode is canceled. When LPF is
activated, most of noise above 1KHz will decay greatly. So we can obtain more stable
and accurate readings on low frequency response.
1.2 Resistance Measurement
A re-configurable divider automatically provides a suitable full-scale range in resistance
measurement mode. The following table summarizes the full-scale ranges and the
reference resistors in each configuration. In 220.00MΩ, if SHIFT pin connects to V-,
the least digit will not be displayed and the other digits and decimal point will shift
right away. So the full scale becomes 220.0MΩ instead of 220.00MΩ.
Configuration
OR1
OR2
OR3
OR4
OR5
OR6
OR7
Full Scale Range
220.00Ω
2.2000KΩ
22.000KΩ
220.00KΩ
2.2000MΩ
22.000MΩ
220.00MΩ
Divider Ratio
R6
R5
R1∥ R4
R1∥ R3
R1∥ R2
R1
R1
Resister Connection
100Ω
1KΩ
10KΩ
100KΩ
1MΩ
10MΩ
10MΩ
1.3 Current measurement for multimeter
ES51921 has 2 automatic and 1 manual current measurement modes for multimeter.
The following table summarizes the full-scale range of each mode. When ES51921
operates in the current measurement modes for multimeter, It takes high input from pin
IVSH or IVSL, low input from pin SGND and reference voltage from pin VR.
Mode
Automatic1
Automatic2
Manual
FC1~4
1,1,0,1
1,1,1,1
0,0,0,0
VBAR
1
1
X
Full Scale
Input Terminal
220.00µA / 2200.0µA IVSL/IVSH V.S. SGND
22.000mA / 220.00mA IVSL/IVSH V.S. SGND
22.000A
IVSH V.S. SGND
Note:
1. The typical connection of input terminal is as the schematic below:
Ver. 3.2
Vin*
9R
100K
R
100K
9
IVSL
IVSH
10/06/23
ES51921
22,000 Counts Auto DMM
1.4 Current measurement for clampmeter
ES51921 has 2 automatic and 4 manual current measurement modes for clampmeter.
The following table summarizes the full-scale range of each mode. When ES51921
operate in the automatic mode1&2, it takes high input from IVSH/IVSL (higher
range/lower range), low input from SGND and reference voltage from VR. When
ES51921 operates in the manual mode1~4, It takes high input from ADP, low input
from SGND and reference voltage from VA+ and VA-.
Mode
Automatic1
Automatic2
Manual1
Manual2
Manual3
Manual4
Note:
FC1~4
1,1,0,1
1,1,1,1
1,1,0,0
1,0,0,0
1,0,1,0
1,0,0,1
VBAR
0
0
X
X
X
X
Full Scale
220.00A / 2200.0A
22.000A / 220.00A
22.000A
220.00A
2200.0A
22000A
Input Terminal
IVSL/IVSH V.S. SGND
IVSL/IVSH V.S. SGND
ADP V.S. SGND
ADP V.S. SGND
ADP V.S. SGND
ADP V.S. SGND
1. Connect VBAR to V- will disable the “µ2” / ”m2” symbol on LCD panel.
2. In DC current modes for clampmeter, ES51921 provides Zero function for offset removing.
3. The typical connection of input terminal for automatic1&2 is as the schematic below:
Vin*
RL
Ver. 3.2
IVSL
9R
IVSH
R
10
10/06/23
ES51921
22,000 Counts Auto DMM
1.5 Capacitance Measurement
The following table summarizes the eight ranges of capacitance measurement mode.
Configuration
C1
C2
C3
C4
C5
C6
C73
C83
Full Scale Range
22.000nF
220.00nF
2.2000uF
22.000uF
220.00uF
2.2000mF
22.000mF
220.00mF
Resistance Ratio
VR4
10kΩ
R9k/R1k
R9k/R1k
R9k/R1k
R9k/R1k
R9k/R1k
Note:
1. In order to obtain an accurate reading, a capacitor must be discharged before measurement begins. The
chip has a built-in discharge mode to automatically discharge the capacitor. In discharge mode, the
LCD displays dIS.C
2. Discharging through the chip is quite slow. We recommend the user to discharge the capacitor with
some other apparatus.
3. In C7~C8 ranges, the bargraph is used to show the measured time in counting down.
4. The C2 range is calibrated by VR near the OVX pin.
5. In ranges of C1~C8, the SHIFT feature is also available to move the digits and decimal points
rightward to prevent the least digit from jumping.
1.6 Continuity Check
Continuity check shares the same configuration with 220.00Ω manual resistance
measurement mode, but with buzzer output to indicate continuity. The buzzer generates a
2KHz sound whenever the digit number is less than 30Ω.
1.7 Diode Measurement
Diode measurement mode shares the same configuration with 2.2000V manual voltage
measurement mode.. The buzzer generates a 2KHz sound whenever the digit number is
less than 30mV.
Ver. 3.2
11
10/06/23
ES51921
22,000 Counts Auto DMM
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 seven decades,
from 22.00Hz to 220.00MHz. The following table summarizes the full-scale range of
the frequency counter. In frequency mode, press VAHz button switches the mode
to/from duty cycle mode.
Range
2
FR1
3
FR2
FR3
FR4
FR5
FR6
FR7
Full Scale
22.00Hz1
220.0Hz1
22.000KHz
220.00KHz
2.2000MHz
22.000MHz
220.00MHz
NOTE:
1
In the range FR1~FR2, the maximum counting number is 2200 counts.
2
In the Range FR1, ES51921 will show 0.00Hz if the input frequency is less than 2.00Hz.
3
In the Range FR2 (manual mode), ES51921 will show 0.0Hz if the input frequency is less than 20.0Hz..
1.8.1Duty Cycle measurement
The duty cycle measurement is available in frequency mode with VAHz operation. Press
VAHZ key when frequency mode is in operation, the ES51921 will switch to duty cycle
measurement mode. Press VAHz key again to switch to frequency measurement mode
also. The duty cycle mode range is within 5.0% to 94.9%. The minimum resolution is
0.1%. If the source frequency duty cycle is smaller than 5.0%, the UL will be shown on
the LCD display. If the duty cycle is larger than 94.9%, the OL will be shown on the
LCD display.
Ver. 3.2
12
10/06/23
ES51921
22,000 Counts Auto DMM
1.9 Temperature measurement mode
Temperature measurement mode takes input signal from ADP pin and reference voltage
from (VA+ - VA-). ES51921 has a built-in ℃-to-℉ scale translation circuit, and only
needs an external ℃ scale application circuit. The application circuit for ℉ scale is
not required. In temperature measurement mode, the default range is 2200.0 ℃ or ℉.
The VBAR pin is used to control the second decimal point (DP2) on the LCD panel.
When VBAR is LOW, DP2 is turned on and the first decimal point (DP1) is turned off.
And the range becomes 220.00℃ and ℉.
1.10 Auto power off and Idle Time selection
ES51921 has a default auto power off function. If the meter is idle for more than the
given idle time, the chip automatically turns the power off. The idle time to trigger the
auto power off function is determined by pin ‘APOSEL’. If pin APOSEL is connected
to V-, the idle time will be set to 30 minutes. If pin APOSEL is connected to DGND or
floating, the idle time will be set to 15 minutes. When APO happens, the state of the
meter is saved. The APO symbol on the LCD panel indicates whether the auto power
off is enabled or not. In some cases, user might want to disable Auto power off. There
are two ways to disable this feature as following:
1. Power on the meter when any of the push functions, except for HOLD is pressed
down.
2. In addition, when RS232 output is active, the auto power off function is also
disabled.
Note:
Powering on the meter while pressing HOLD and lasts 2 seconds turns on all LCD segments until HOLD
is pressed again.
1.11 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.
1.12 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.
Ver. 3.2
13
10/06/23
ES51921
22,000 Counts Auto DMM
2. Measurement Mode Switching
Measurement mode depends on the logic level of SLACDC, FC1, FC2, FC3, FC4, FC5,
and KEY. When FC5 is high, the measurement mode list is below.
SLACDC
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
FC1
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
FC2
0
1
1
0
1
1
0
0
0
0
0
1
0
1
1
1
0
1
1
0
1
1
0
0
0
0
0
1
0
1
1
1
FC3
1
0
1
0
1
0
0
1
0
1
0
1
1
1
0
0
1
0
1
0
1
0
0
1
0
1
0
1
1
1
0
0
FC4
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
1
Mode
Voltage Measurement
Auto DC Current Measurement(µA)
Auto DC Current Measurement(mA)
3
22A DC Current Measurement(A)
DCmV 220.00mV
2
Manual DC 22.000A
Manual DC 220.00A
Manual DC 2200.0A
Manual DC 22000A
Resistance Measurement
Continuity Check
Resistance Measurement
Frequency Measurement
Capacitance Measurement
Temperature Measurement
Resistance Measurement
Voltage Measurement
Auto AC Current Measurement(µA)
Auto AC Current Measurement(mA)
3
22A AC Current Measurement(A)
ACmV 220.00mV
2
Manual AC 22.000A
Manual AC 220.00A
Manual AC 2200.0A
Manual AC 22000A
1
ADP0(22000)
ADP1(2200.0)
ADP2(220.00)
ADP3(22.000)
ADP4(2.2000)
Temperature Measurement
Capacitance Measurement (Clamp)4
Function of KEY
DCV ↔ ACV
DCA ↔ ACA
DCA ↔ ACA
DCA ↔ ACA
DCmV ↔ ACmV
DCA ↔ ACA
DCA ↔ ACA
DCA ↔ ACA
DCA ↔ ACA
Ω ↔ Continuity
Continuity ↔ Diode
Ω ↔ Continuity ↔ Diode
—
—
℃ ↔ ℉
Ω ↔ Diode
ACV ↔ DCV
ACµA ↔ DCµA
ACmA ↔ DCmA
ACA ↔ DCA
ACmV ↔ DCmV
ACA ↔ DCA
ACA ↔ DCA
ACA ↔ DCA
ACA ↔ DCA
—
—
—
—
—
℉ ↔ ℃
—
X means “don’t care”.
Note1: When FC5 is high, the ADP0, ADP1, ADP2, ADP3 and ADP4 modes can display minus sign.
Note2: The manual DC/AC 22A, 220A, 2200A and 22000A modes are designed for clampmeter.
Note3: DC 22A and AC 22A current measurement modes, (FC1~4) = (0, 0, 0, 0), are designed for
multimeter.
Note4: It provides the ranges from 2.2uF to 220mF in this mode.
Ver. 3.2
14
10/06/23
ES51921
22,000 Counts Auto DMM
When FC5=low, KEY is disabled and the measurement mode list is below.
SLACDC
FC1
FC2
FC3
FC4
Mode
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
1
1
1
0
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
0
1
1
0
0
0
0
0
1
0
1
1
1
0
1
1
0
1
1
0
0
0
0
0
1
0
1
1
1
1
0
1
0
1
0
0
1
0
1
0
1
1
1
0
0
1
0
1
0
1
0
0
1
0
1
0
1
1
1
0
0
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
1
1
1
1
0
0
0
0
0
1
1
1
1
0
0
0
1
DC Voltage Measurement
Auto DC Current Measurement(µA)
Auto DC Current Measurement(mA)
3
22A DC Current Measurement(A)
DC 220.00mV
2
Manual DC 22.000A
Manual DC 220.00A
Manual DC 2200.0A
Manual DC 22000A
Resistance Measurement
Continuity Check
Diode Measurement
Frequency Measurement
Capacitance Measurement
Temperature Measurement (oC)
Resistance Measurement
AC Voltage Measurement
Auto AC Current Measurement(µA)
Auto AC Current Measurement(mA)
3
22A AC Current Measurement(A)
AC 220.00mV
2
Manual AC 22.000A
Manual AC 220.00A
Manual AC 2200.0A
Manual AC 22000A
1
ADP0(22000)
ADP1(2200.0)
ADP2(220.00)
ADP3(22.000)
ADP4(2.2000)
Temperature Measurement (oF)
Capacitance Measurement (Clamp)4
Push KEY to
enable LPF mode
O
O(VBAR to V-)
O(VBAR to V-)
O
O
O
O
O
X means “don’t care”.
Note1: When FC5 is low, the ADP0-ADP4 modes can not display minus sign.
Note2: The manual DC/AC 22A/220A/2200A/22000A modes are designed for clampmeter.
Note3: DC 22A and AC 22A Current Measurement mode, (FC1~4) = (0, 0, 0, 0), is designed for
multimeter.
Note4: It provides the ranges from 2.2uF to 220mF in this mode.
Ver. 3.2
15
10/06/23
ES51921
22,000 Counts Auto DMM
3. Push function
All the enabled push functions will be reset when the measurement mode is changed by
rotary switch. Change measurement mode by KEY function will reset enabled Range,
Hold, Max/Min, REL, and Zero functions. The following table lists the available
function versus every measurement mode.
Function
Mode
Range
Hold
Max/Min
REL
Zero
VAHz
Voltage
O
O
O
O
X
O
Current1
O
O
O
O
X
O
Current2
X
O
O
AC
DC
O
Resistance
O
O
O
O
X
X
Capacitance
O
O
O
O
X
X
Frequency
O
O
X
X
X
O
Duty cycle
X
O
X
X
X
X
Continuity
X
O
O
O
X
X
Diode
X
O
O
O
X
X
Temperature
X
O
O
O
X
X
ADP
X
O
O
O
X
X
Note:
Current1 includes Auto µA, Auto mA and 22A modes.
Current2 includes Manual 2.2A, 22A, 220A, 2200A and 22000A modes.
3.1 HOLD and Delay 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. ES51921 provides a Delay HOLD feature. To activate Delay HOLD
feature, press down the HOLD bottom and last for 2 seconds. The meter will delay for 6
seconds, than enters HOLD mode. In the 6-secnod delayed time, the HOLD symbol on
LCD panel will blink. To cancel the delayed state, push the HOLD bottom again.
Ver. 3.2
16
10/06/23
ES51921
22,000 Counts Auto DMM
Normal mode Push < 2s HOLD mode
(Auto/Manual) Push < 2s
(Manual)
Push > 2s
Push < 2s
Push > 2s
6sec past
Delay State
(Auto/Manual)
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
Manual
Mode
1 push > 1 sec
Range up
1 push < 1 sec
Measurement Mode
220.00mV(DC/AC)
Auto
VR1
V(DC/AC)
VR2 – VR5
Auto 220V/1010V
(Set VST to low)
VR4-VR5
Auto µA(DC/AC)
R1 – R2
Auto mA(AC/DC)
R1－R2
22 A(DC/AC)
Fixed
Auto 22A/220A
(DC/AC)
R1 – R2
Auto 220A/2200A
(DC/AC)
R1－R2
Ω
OR1 - OR7
Capacitance
C1 – C8
Capacitance
(Clamp mode)
Continuity
Diode
Frequency
C3 – C8
fixed
fixed
FR1 – FR7
Manual
Control Range
Initial Range
VR1
220.00mV
220.00mV
VRi → VRi + 1,
2.2000V – 1010.0V
2.2000V
VR5 → VR2
VRi → VRi + 1,
2.2000V – 1010.0V
220.00V
VR5 → VR2
R1 → R2,
220.00µA – 2200.0µA 220.00µA
R2 → R1
R1 → R2
22.000mA – 220.00mA 22.000mA
R2 → R1
Fixed
22.000A
22.000A
R1 → R2,
22.000A – 220.00A
22.000A
R2 → R1
R1 → R2
220.00A – 2200.0A
220.00A
R2 → R1
ORi → ORi + 1,
220.00Ω – 220.00MΩ
220.00Ω
OR7 → OR1
Ci → Ci + 1,
22.000nF – 220.00mF
22.000nF
C8 → C1
Ci → Ci + 1,
2.2000μF – 220.00mF
2.2000μF
C8 → C3
fixed
220.00Ω
220.00Ω
fixed
2.2000V
2.2000V
FRi → FRi + 1
22.00Hz – 220.00MHz
22.00Hz
FR7 → FR1
Note: Pushing RANGE resets all existing special modes.
Ver. 3.2
17
10/06/23
ES51921
22,000 Counts Auto DMM
3.3 KEY
See Section “Measurement Mode Switching” for the function of this pin.
3.4 REL + HOLD
In REL mode, the LCD panel displays DN+K - DN, where DN = 1, 2, 3, … , DN is the
last value before REL is pushed, and DN+K is the current value. If REL is pushed again
in REL mode, the meter displays the reference value. The meter returns to normal
operation if REL is pressed and held for longer than one second. Pressing HOLD in
REL mode makes the meter stop updating the LCD panel.
push REL
Original State
(Auto/Manual)
push HOLD
〝REL〞active.
〝REL〞and〝H〞active.
Hold the relative value
The relative value
push REL
push HOLD
Note: It’s possible that the relative value exceeds 22,000 or –22,000 counts. Such
relative values are displayed. The LCD panel shows OL in REL mode only if DN or
DN+K is more than 22,580 counts.
3.5 Max/Min + HOLD
The meter displays the maximum or minimum value of the input in Max/Min mode.
When Max/Min is pressed for the first time, the meter displays the maximum value.
When Max/Min is pressed again, the meter displays the minimum value. When
Max/Min is pressed for the third time, the meter displays current value with Max/Min
blinking. The meter returns to normal operation if Max/Min is pressed and held for
longer than one second. Pressing HOLD in Max/Min mode makes the meter stop
updating the maximum or the minimum value.
1 push<1s
Original state
(Automatic/manual)
1 push>1s
1 push>1 sec
1 push>1 sec
“MAX” active 1push<1s “MIN” active 1push<1s “Max” “MIN” blink
min value
current value
max value
Push HOLD
1push<1s
Push HOLD
Push HOLD
“MAX”“MIN” “H” blink
“MIN” “H” active
“MAX” “H” active
hold max value. 1push<1s hold min value. 1push<1s hold current value.
1push<1s
Ver. 3.2
18
10/06/23
ES51921
22,000 Counts Auto DMM
3.6 Relative + Max/Min + HOLD
Max/Min mode can be nested in REL mode. The meter displays the maximum or
minimum value relative to the reference when Max/Min is pressed in REL mode.
Pressing HOLD under REL + Max/Min makes the meter stop updating the LCD panel.
Original State
(Auto/Manual)
Push REL
Push REL
〝REL〞active.
The relative value
Push Max/Min > 1s
Push Max/Min
〝REL〞and〝Max〞active.
〝REL〞and〝Min〞active.
〝REL〞〝Max〞〝Min〞
Maximum rel. value
Minimum rel. value
blink. Current rel. value
Push Max/Min
Push HOLD
〝REL〞,〝Max〞,
〝H〞active. Hold
max. rel. value
Push Max/Min
Push HOLD
〝REL〞, 〝Min〞,
Push Max/Min
〝REL〞
〝Max〞
,
〝Min〞
,
,
〝H〞blink. Hold the
〝H〞active. Hold
min. rel. value
Push HOLD
Push Max/Min
current rel. value
Push Max/Min
3.7 Zero : In manual DC 22.000A, 220.00A, 2200.0A and 22000A measurement
modes, the REL pin changes to control Zero function instead of relative function. In
Zero mode, the LCD panel displays DN+K - DN, where DN = 1, 2, 3, … , DN is the last
conversion value before Zero is pushed, and DN+K is the current conversion value. If
Zero is pushed again in Zero mode, the meter will refresh the DN value and displays the
DN+K - DN again. The meter returns to normal operation if Zero is pressed and held for
longer than one second. Pressing HOLD in Zero mode makes the meter stop updating
the LCD panel. In Zero mode, LCD will not show any symbol to remind users of Zero
mode is active. In 2-range auto DCA modes for clampmeter (220.00A/2200.0A or
22.000A/220.00A), the system will stay in automatic mode, even if the Zero function is
activated. In other words, it could achieve real automatic operation. In automatic mode,
Zero function could not be entered from higher range, but it could be still activated if
current range is lower one. This is because most residual current value is so small that
Ver. 3.2
19
10/06/23
ES51921
22,000 Counts Auto DMM
the range could not be higher one in automatic mode. When enter Zero mode from
lower range, the system will store the nonzero counts (residual current value). If the
range goes up to higher one automatically, the nonzero counts will be divided by ten.
So this function will still work well in automatic modes.
State diagram for Zero mode:
Original State
Press Zero
Press Zero > 1s
‘Zero’ Active
Press Zero < 1s
Show DN+K - DN
State diagram for Zero + HOLD mode:
Original State
Press Zero
Press Zero > 1s
‘Zero’ Active
Press Zero < 1s
Show DN+K - DN
Press Hold
‘Zero’ ‘Hold’ Active
Stop LCD upgrading
State diagram for Zero + Max/Min + HOLD mode:
Original State
Press Zero
Press Zero > 1s
‘Zero’ Active
Press Zero < 1s
Show DN+K - DN
Press Max/Min
Press Max/Min > 1s
‘Zero’ ‘Max’ Active
‘Zero’ ‘Min’ Active
Max. DN+K - DN Value
Press HOLD
Min. DN+K - DN
Vl
Press Max/Min < 1s
Press HOLD
‘Zero’ ‘Max’ ‘Hold’ Active
Hold Max. DN+K - DN Value
‘Zero’ ‘Min’ ‘Hold’ Active
Hold Min. DN+K - DN Value
‘Zero’ ‘Max’ ‘Min’ blink.
Current DN+K - DN Value
Press HOLD
‘Zero’ ‘Max’ ‘Min’ ‘Hold’ blink.
Hold Current DN+K - DN Value
Press Max/Min < 1s
Ver. 3.2
20
10/06/23
ES51921
22,000 Counts Auto DMM
4. Serial Data Output
The RS232 function will be activated if the RS232 pin is pulled to and asserts at V-.
The serial data sent to SDO pin once 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
LSB is sent first and the MSB is sent last.
single package
0V
-3V
0
D0 ~D6
LSB
p 1
P
MSB
One data block consists of 14 packets, or 140 bits. The following figure shows the
format of a data block. The range packet indicates the full scale range of the meter.
Digit4 through digit0 are just the digits on the LCD panel. The function packet
indicates the measurement mode of the meter. Status, option1~4 give the status of the
meter. CR and LF are delimiters used to separate the blocks.
Ver. 3.2
21
10/06/23
ES51921
22,000 Counts Auto DMM
all packets
The meter always outputs the current input value to the serial port in spite of HOLD
mode. The detailed data format of each packet is listed at next page.
Ver. 3.2
22
10/06/23
ES51921
22,000 Counts 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-FC5 switch.
Code
0111011
0111101
0111111
0110000
0111001
0110011
0110101
0110001
0110010
0110110
0110100
0111110
1.
Measurement Mode
Voltage
Auto µA Current
Auto mA Current
22 A current
Manual A Current
Ω
Continuity
Diode
1
Frequency
Capacitance
2
Temperature
ADP
VBAR=0
VBAR=1
Don’t care
Auto µA Current
Auto mA Current
Auto 220.00A/2200.0A
Auto 22.000A/220.00A
Don’t care
When the function code = 0110010, the measurement mode is determined by judge bit of Status
packet. If judge bit is 1, it means frequency mode. If judge bit is 0, it means duty cycle mode.
2.
When the function code = 0110100, the judge bit in the Status packet determines whether the unit is
Celsius or Fahrenheit. And the digit4~0 only presents Celsius value whatever the mode is oC or oF.
3.
When the function code = 0111101 or 0111111, the measurement mode is determined by VBAR bit.
4.2 RANGE
This packet indicates the full-scale range of the meter. When the meter operates in
continuity mode or diode mode, this packet is always 0110000 since the full-scale
ranges in these modes are fixed. The following table lists the code for each range in
each measurement mode.
Code
V
*2-range auto A
22 A Manual A
0110000 2.2000V Lower Range(IVSL) 22.000 A 2.2000A
0110001 22.000V Higher Range(IVSH)
22.000A
0110010 220.00V
220.00A
0110011 2200.0V
2200.0A
0110100 220.00mV
22000A
0110101
0110110
0110111
*It includes auto µA, mA, 22.000A/220.00A, 220.00A/2200.0A.
Ver. 3.2
23
ADP
ADP4
ADP3
ADP2
ADP1
ADP0
Ω
220.00Ω
2.2000KΩ
22.000KΩ
220.00KΩ
2.2000MΩ
22.000MΩ
220.00MΩ
Frequency Capacitor
22.00Hz 22.000nF
220.0Hz 220.00nF
2.2000µF
22.000KHz 22.000µF
220.00KHz 220.00µF
2.2000MHz 2.2000mF
22.000MHz 22.000mF
220.00MHz 220.00mF
10/06/23
ES51921
22,000 Counts Auto DMM
4.3 DIGIT 4 – DIGIT 0
Digit 4 is the first significant digit on the LCD panel, and digit 0 is the least significant
digit.
Digit
0
1
2
3
4
5
6
7
8
9
Code
0110000
0110001
0110010
0110011
0110100
0110101
0110110
0110111
0111000
0111001
4.4 STATUS
The format of this package 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 °C and is 0 of the unit is °F. Sign field indicates whether the minus sign on the
LCD panel is on or off. BATT field is one when battery low condition is true. OL
indicates input overflow.
0
BIT6
1
BIT 5
1
BIT 4
Judge
BIT 3
Sign
BIT 2
BATT
BIT1
OL
BIT 0
4.5 OPTION 1
This packet contains information on the push function of the meter. The format is
shown below. MAX, MIN or RMR bit will be high if the meter enter Max/Min function
and stay at state of maximum, minimum or current value respectively. REL bit will be
high if meter enters REL/Zero mode.
0
BIT 6
Ver. 3.2
1
BIT 5
1
BIT 4
MAX
BIT 3
24
MIN
BIT 2
REL
BIT 1
RMR
BIT 0
10/06/23
ES51921
22,000 Counts Auto DMM
4.6 OPTION 2
0
BIT 6
1
BIT 5
1
BIT 4
UL
BIT 3
0
BIT 2
0
BIT1
0
BIT 0
Under the following conditions, the UL bit will be set to 1.
1. In 22.00Hz range, the input frequency is less than 2.00Hz.
2. In 220.0Hz range, the input frequency is less than 20.0Hz.
3. In duty cycle mode, the reading is less than 10.0%.
4.7 OPTION 3
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.
0
BIT 6
1
BIT 5
1
BIT 4
DC
BIT 3
AC
BIT 2
AUTO
BIT 1
VAHZ
BIT 0
4.8 OPTION4
This packet contains information on the operation mode of the meter. The format is
shown below. VBAR will be set to high, only when the VBAR pin is connected to V-.
Hold bit is set to high when meter enters hold mode. LPF bit is set to high when the
low-pass-filter feature is activated.
0
BIT 6
1
BIT 5
1
BIT 4
0
BIT 3
VBAR
BIT 2
Hold
BIT 1
LPF
BIT 0
4.9 CR
Carriage returns. The transmitted code is 0001101.
4.10 LF
Line feed. The transmitted code is 0001010.
Ver. 3.2
25
10/06/23
ES51921
22,000 Counts Auto DMM
5. Miscellaneous
The conditions on which the meter turns on the buzzer include:
(1) Changing measurement mode generates one beep.
(2) Pressing any of the push functions generates one beep, if the function is valid.
(3) Power on and re-power on generate one beep.
(4) Input overflow in voltage (220mV range not included) 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 30Ω(30mV)
(6) Auto power off generates a 2KHz beep that lasts for 1.5 seconds.
The following figures show the output waveform from the BUZOUT pin.
0.5 mS
(a) Continuous 2KHz beep
0.15 sec
0.3 sec
(b) 3.33 beep/sec
Ver. 3.2
26
10/06/23
ES51921
22,000 Counts Auto DMM
5.1 LCD Panel Configuration
BP1
% ℃ ℉ REL MAX MIN ADP0
BATT AUTO MANU HOLD
ADP1 ADP2 ADP3 ADP4
APO
DC
n µ1 m1 F
µ2 m2 V A
M K Ω Hz
AC
RS232
22.5
BP2
BP3
BP4
0
5
10
15
20
BP1
BP2
BP3
BP4
SEG01 SEG02 SEG03 SEG04 SEG05 SEG06 SEG07 SEG08 SEG09 SEG10 SEG11
BATT APO
DC AUTO
5F
5A
5B MANU 4F
4A
4B
bar- RS232 AC
5E
5G
5C
DP4
4E
4G
4C
bar0
bar2
bar4
bar6
bar8
5D
bar11 bar13 bar15
4D
bar18
bar1
bar3
bar5
bar7
bar9 bar10 bar12 bar14 bar16 bar17 bar19
BP1
BP2
BP3
BP4
SEG12 SEG13 SEG14 SEG15 SEG16 SEG17 SEG18 SEG19 SEG20 SEG21 SEG22
O
O
1A
HOLD
3F
3A
3B
C
F
2A
%
DP3
3E
3G
3C
DP2
2F
2G
2B
DP1
1F
1G
bar20 bar22
3D
bar25 bar27
2E
2D
2C
bar32
1E
1D
bar21 bar23 bar24 bar26 bar28 bar29 bar30 bar31 bar33 bar34 bar35
BP1
BP2
BP3
BP4
SEG23 SEG24 SEG25 SEG26 SEG27 SEG28 SEG29 SEG30
μ2
1B
V
A
REL ADP1
n
m2
μ1
1C
M
K
Ω
Hz
MAX ADP2
bar36 bar38 bar40 bar42 bar44 MIN ADP3
m1
bar37 bar39 bar41 bar43 bar45 ADP0 ADP4
F
Ver. 3.2
27
10/06/23
ES51921
22,000 Counts Auto DMM
LCD Backplane Waveform
V- +3.2
V- +3.1
VV-
V- +3.2
V- +3.1
VV-
V- +3.2
V- +3.1
VV-
V- +3.2
V- +3.1
VV-
V- +3.2
V- +3.1
V-
5.2 LCD display on condition
LCD Annunciator
V
A
Ω
F
Hz
%
DC
AC
AUTO
MANU
HOLD
REL
MAX / MIN
m1
µ1
n
m2
µ2
M
K
℃
℉
APO
RS232
Ver. 3.2
Condition
In voltage measurement mode, and diode measurement mode.
In current measurement mode.
In resistance measurement mode, and continuity mode.
In capacitance measurement mode.
In continuity check mode.
In diode mode.
In frequency mode.
In duty cycle mode.
In DC voltage or DC current mode.
In AC voltage or AC current mode.
When automatic full scale range selection is enabled.
In manual mode.
When HOLD function is enabled.
When Relative function is enabled.
When Maximum or Minimum function is enabled.
In capacitor measurement mode and the full scale range is in the order of mF.
In capacitor measurement mode and the full scale range is in the order of uF.
In capacitor measurement mode and the full scale range is in the order of nF.
In voltage or current measurement mode and the full scale range is in the order of 10-3.
In current measurement mode and the full scale range id in the order of uA.
In resistance measurement mode and the full scale range is in the order of MΩ
In 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 ℉
When auto power off function is enabled.
When RS232 output is enabled.
28
10/06/23
ES51921
22,000 Counts Auto DMM
5.3 Programmable LCD Segment Display
ES51921 supports a “Programmable LCD Segment Display”(PLSD) feature. Except
capacitor measurement mode & duty cycle measurement, all modes could support
PLSD. PLSD allows the meter designer to process or modify the conversion results
by external microprocessor and displayed on LCD panel. The more accurate and
stable reading would be possible. ES51921 provides uPLCD, SCLK and SDATA pins
to archive the PLSD feature. Connect uPLCD to V- to enable PLSD feature and
received the serial data from SDO pin. After the data processing, transfer the display
data through the SDATA and give a clock signal to SCLK. ES51921 will receive the
display data through SDATA at the falling edge of clock signal, then display the data
on LCD panel. Only the segments shown below could be modified, other segments
are still controlled by ES51921. When capacitor or duty mode is selected, the LCD
display is determined by ES51921.
About the details of serial data format, please refer to page 21-25.
D5
a
D4
a
D3
a
D2
a
D1
a
ADP0
f
b
f
g
b
f
g
b
f
g
b
f
g
b
g
ADP1
ADP2
Lsign
c
e
e
c
d
e
d
DP4
c
e
d
DP3
c
e
d
DP2
c
d
ADP3
ADP4
DP1
PLSD Data format:
B1
B2
B3
B4
B5
B6
B7
OL ADP0 ADP1 ADP2 ADP3 ADP4 D1a
B8
B9
B10
B11
B12
D1b
D1c
D1d
D1e
D1f
B13
B14
B15
B16
B17
B18
B19
B20
B21
B22
B23
B24
D1g
DP1
D2a
D2b
D2c
D2d
D2e
D2f
D2g
DP2
D3a
D3b
B25
B26
B27
B28
B29
B30
B31
B32
B33
B34
B35
B36
D3c
D3d
D3e
D3f
D3g
DP3
D4a
D4b
D4c
D4d
D4e
D4f
B37
B38
B39
B40
B41
B42
B43
B44
B45
B46
D4g DP4 D5a D5b D5c D5d D5e D5f D5g Lsign
Note: The B1 should be sent first and the B46 sent last.
Set the OL bit = 1, the buzzer output will be active for 3.3beep/sec in voltage &
current mode. And if auto range is available, it will change to higher range if LCD
bar44 is active also.
Ver. 3.2
29
10/06/23
ES51921
22,000 Counts Auto DMM
Block diagram:
μP
RS232 DATA
...
SDO
SCLK
PLSD DATA
SDATA
ES51921
uPLCD
FC1-FC5/SLACDC
Operation timing diagram for PLSD feature is shown as below:
46 clock pulses
tdelay
RS232 data is received
Start to send PLSD data
…
SCLK
SDO
CR
LF
PLSD data
SDATA
tHIG
tLOW
tF
tR
SCLK
tSETU
tHOLD
SDATA
Parameter
Symbol Min. Typ. Max. Unit
SCLK clock frequency
10
100 KHz
fSCLK
SCLK clock time “L”
4.7
tLOW
us
SCLK clock time “H”
4.0
tHIGH
Data input setup time
tSETUP 200
ns
Data input hold time
tHOLD 100
SCLK/SDATA rising time
1.0
tR
us
SCLK/SDATA falling time
0.3
tF
SCLK delay time after
0.1
100
ms
tdelay
receiving RS232
Ver. 3.2
30
10/06/23
ES51921
22,000 Counts Auto DMM
5.4 Operating Timing
ES51921 incorporates a dual slope ADC with four phases: ZI, AZ, INT and DINT.
The ADC consists of a high-resolution part for digital display and a high speed part
for the bar-graph display. The time of each phase is shown below:
*Voltage /Current /Ohm/Cont./Diode/ADP measurement:
Phase
ZI
AZ
INT
DINT
High resolution
100ms
74ms
100ms
226ms
High speed
10ms
7.4ms
10ms
22.6ms
*Capacitance measurement:
Range
22.000nF
220.00nF
2.2000uF
22.000uF
220.00uF
2.2000mF
22.000mF
220.00mF
Maximum measurement period
0.5sec
0.5sec
0.5sec
0.5sec
0.5sec
1sec
5sec
25sec
*Frequency measurement
The measurement cycle = 1.05 sec
P.S. In the frequency measurement with auto mode, if the range is changed, the internal clock rate will
increase five times and the new measurement cycle becomes 0.21 sec until the range is stable.
Ver. 3.2
31
10/06/23
ES51921
22,000 Counts Auto DMM
6. Test Circuit
1. Voltage test
4. Current test
AGND
OVSG
100
1K
OR1
VR5
VR4
VR3
VR2
ADO
10.01K
101K
1.111M
D2
D1 1.0u
4.7u
1.0u
3.9K
2K
mA
9
V
R
100K
uA
uA
mA
uA
V
R
1
mA
90
A
AGND
SGND
20A
0.99
ADI
ACVL
ACVH
TEST5
0.1u
3.9K
3K
88M
0.01
IVSH
100K
IVSL
900
5. Diode test
10M
AGND
-100mV
OVH
100
Voltage input
Z1
6V
Z2
PTC
1.5K
2. Resistor test
VR1
PTC
1.5K
22n
OVX
OHMC4
220n
OHMC3
330n
OHMC2
47n
100
Z1
6V
Z2
100
1K
10.01K
101K
1.111M
OHMC1
OVH
OVSG
10M
1.111M
VR2
OVSG
6. Low battery
9V
OR1
VR5
VR4
VR3
VR2
BA
680K
LBAT9
TT
SGND
AGND
270K
0.1u AGND
V-
0V
3. Capacitor test
20k
PTC
1.5K
Z1
6V
Z2
100k
OVX
220p
100
VA+
OR1
VR5
VR4
VR3
VR2
CA+
CA-
ADPin+
100K
ADPin-
F
R
E
Q
VAADP
-100mV
SGND
200
2.2u
AGND
PTC
1.5K
R9k
Fin
R1k
Ver. 3.2
8. Frequency test
OVH
OVSG
100
1K
10K
101K
1.111M
7. ADP test
32
10/06/23
ES51921
22,000 Counts Auto DMM
7. Application Circuit
7.5V ZI
Microprocessor
5.6V ZI
3V
μA
900
90
9
A
0.99
0.01
2K
3.9K
+
1μ
4.7μ
10K
+
SEG27
SEG28
SEG29
SEG30
(60) NC
FREQ
SLEEP 200
BUZIN
LPFC3 22n
(55) LPFEN
LPFOUT
LPFC2 4.7n
1n
LPFC1
NC
(50) NC
R1K
R9K
CA+ 470n
CA(45) VBAR
10M
VR1
V220m
100K
VAVA+
(40) ADP
SGND
D1
BKLIT
NC
(100) MAX/MIN
KEY
REL_ZERO
RANGE
HOLD
(95) ANNUNC
BP1
BP2
BP3
BP4
(90) SEG01
SEG02
SEG03
SEG04
SEG05
(85) SEG06
SEG07
SEG08
SEG09
SEG10
(80) SEG11
SEG12
SEG13
SEG14
SEG15
(75) SEG16
SEG17
SEG18
SEG19
SEG20
(70) SEG21
SEG22
SEG23
SEG24
SEG25
SEG26
9K
+
1μ
mV
2.2μ
1K
V-
1.5K
PTC
1815
Fin
Notes:
1. Most of pins are protected by the ESD protection circuits. However pins, V+, V-, AGND, DGND and
VR1 are not protected enough because the parasitic effect must be decrease. Therefore enough external
protection is needed for assembling, carrying and keeping. In addition, components connecting to these
unprotected pins have to be soldered on board before the IC is soldered.
2. Cp is the compensation capacitor for measuring capacitance. Its value depends on the parasitic
capacitor on the PCB board.
3. Light shielding for the diodes and Zeners.
Ver. 3.2
33
10/06/23
...
3K
V+ (1)
V+
DGND
AGND
AGND (5)
CH+
10n
CHμA
22n
CIH
100k
BUFFH
47n
μA
CAZH (10)
CL+
100n
mA
CL220n
CIL
470n
CAZL
mA
100k
BUFL (15)
10k
RAZ
A
100K
IVSH
100K
IVSL
100K
OVX
100
20K
OVH (20)
220p
OVSG
1.5K
PTC
100 OR1
1K VR5
10.01K VR4
VR3 (25)
101K
VR2
1.111M TEST5
ACVL
ACVH
ADI (30)
0.1μ
ADO
22n
3.9K
OHMC4
220n
OHMC3
+
1μ
330n
OHMC2
88M
47n
OHMC1 (35)
D2
NC
4.7μ
VRH
VR
91K
LCD display
R
C
4M
ES51921
mA
10μ
0.1μ
VAHZ
BUZOUT
BKOUT
OSC2
OSC1
SCLK
SDATA
uPLCD (110)
RS232
APOSEL
BKSEL
VST
SHIFT (115)
CESEL
SLACDC
FC5
FC4
FC3 (120)
FC2
FC1
SDO
C+
C- (125)
VVLBAT9 (128)
10μ +
0.1μ
V470n
+
5.6V ZI
ES51921
22,000 Counts Auto DMM
7.1 Appendix: Average rectified circuit
1
2
3
4
ES51922 Average Circuit
D
D
Type ( II )
VR1
2K
R1
C
C1
C3
+ C2
1uF
1uF
+
R2
3.9K
3K
VR1
TEST5
0.1uF
2K
R1
6.2K
C1
+
Type ( I )
10uF
TEST5
ADI
R3
3.9K
ADI
R2
7.5K
R4
88M
C
R3
7.5K
C2
1uF
+
D1
1N4148
D2
IN4148
D1
ACVH
C4
4.7uF
D2
1N4148
ADO
ACVH
IN4148
ADO
ACVL
ACVL
B
B
Title
A
Size
A
Number
Revision
A4
Date:
File:
1
2
3
13-Jun-2007
D:\Protel file\ES51922 Serial.ddb
Sheet of
Drawn By:
4
Note: 88MΩ resistors could be omitted at Type(II) circuit
Ver. 3.2
34
10/06/23
ES51921
22,000 Counts Auto DMM
8. Package
1. 128L QFP Topview
2. Dimension Parameters
Ver. 3.2
35
10/06/23