ES51945(5000counts)

ES51945(5000counts)
Dual Display/No Cap
Features
• 5000 counts dual LCD display
• 128L QFP package
• 3V DC power supply
• ADC Conversion rate : 3.3 times/s
• Full automatic measurement
*Voltage measurement: 500.0mV – 1000V
*Current measurement: 50.00A/500.0A,
500A/5000A
*Flame rod DCuA mode measurement:
500.0uA/5000uA both manual ranges
*Not contact AC electric field detection
*Frequency mode active on sub-display for ACA
500.0Hz ~ 5000Hz
*Resistance measurement: 500.0Ω – 50.00MΩ
*Frequency counter with duty cycle display:
500.0Hz – 50.00MHz
5% – 95% (< 10kHz)
• ZERO function for DCA mode
• Voltage high crest factor detection
(Taiwan patent no.: 234661)
• Voltage & Current measured simultaneously
ACV+ACA, DCV+DCA
• Diode measurement & continuity check
• Auto range temperature mode(500.0 0C /5000 0C)
• Temperature mode with internal scale translation
circuit from 0C to 0F
• Push functions:
*Single Select key operation:
• CE selection (DC/AC 1010V, DC/AC 610V)
• LCD segment check when power on
• Auto power off (30min/15min)
• Sleep state indicative signal output
• Re-power on
• On-chip buzzer driver
• High Voltage (HV) danger indication
• Low battery multi-level detection
Description
ES51945 is an integrated analog-to-digital
converter (ADC) with dual 5,000-count LCD
display, which 4-digit main-display (AC/DC
Voltage) and 4-digit sub-display (AC/DC
Current), automatic range selection, and 3V
DC power supply. ES51945 could be
designed for a clamp-meter with V & A
measurement simultaneously. Automatic
range selection is provided for voltage
(AC/DC)
measurement,
resistance
measurement, current measurement and
frequency counter. Other features include
offset removing feature for DCA clampmeter,
data holding, duty cycle measurement, diode
measurement, temperature measurement,
continuity checking, multi-level low battery
detection, auto power off, re-power on,
backlight driver, and buzzer output driver.
Zero for DCA
Hz for ACA
*Range change function
*Data hold function
*Back light function
*Semi-auto Calibration Operation
(Taiwan patent no.: 367334)
• Low pass filter for ACA measurement
• Band-gap reference voltage output
v2.3
1
10/06/25
B
A
ADO_A
ADI_A
TEST5A
ACVLA
ACVHA
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHM C4
OHM C3
OHM C2
OHM C1
VR_A
DACAO
VR
DACVO
OR1
VR5
VR4
VR3
VR2
OVSG
C
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
29
30
31
32
33
34
35
36
37
38
D
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
v2.3
NC
APOSEL
SVR
S50V
NC
NC
LCDCAP
OSC2
OSC1
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
NC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
ES51945(5000counts)
Dual Display/No Cap
Application
Clamp meter
Pin Assignment
LQFP-128L
1
1
2
CESEL
TSEL
ALARM1
DIS_LPF
DISDGB
DISDCA
NC
BKLIT
SEL
HOLD
RANGE
SAC
FC4
FC3
FC2
FC1
CC+
LBAT9
VVV+
V+
DGND
AGND
AGND
3
ES51945
2
3
2
4
D
SEG22
SEG23
SCL
SDA
CAL_EN
FREQ
BUZIN
SLEEP
LPFOUT
LPC3
LPC2
LPC1
OVH1
OVH
OVX
R1K
R9K
CA+
CASGND
TEST5V
ADO_V
ADI_V
ACVH_V
ACVL_V
VR1
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
C
B
A
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10/06/25
ES51945(5000counts)
Dual Display/No Cap
Pin Description
Pin No
1
2
3
Symbol
ADO_A
ADI_A
TEST5_A
Type
O
I
O
4
ACVL_A
O
5
ACVH_A
O
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25-28
29
30
31
32
33
34
35
36
37
38
39
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHMC1-4
VR_A
DAC_AO
VR
DAC_VO
OR1
VR5
VR4
VR3
VR2
OVSG
VR1
I/O
I/O
I
I
I
I
O
O
O
O
I/O
I/O
O
I/O
I/O
O
O
O
O
O
I
O
I
O
O
O
O
O
O
O
I
40
ACVL_V
O
41
ACVH_V
O
42
43
44
45
46
47
48
49
50
51
52
ADI_V
ADO_V
TEST5_V
SGND
CACA+
R9K
R1K
OVX
OVH
OVH1
I
O
O
G
I/O
I/O
O
O
I
O
O
v2.3
Description
Output of internal AC to DC OP Amp for ACA mode.
Negative input of internal AC to DC OP Amp for ACA mode.
Buffer output of SGND for ACA mode
DC signal low input in ACA mode. Connect to negative output
of external AC to DC converter.
DC signal high input in ACA mode. Connect to positive output of
external AC to DC converter.
Cap for duty-cycle mode
Cap for duty-cycle mode
For ADP mode. De-integrating voltage negative input
Current measurement input for higher range.
Current measurement input for lower range.
Measurement input in ADP mode. (Current/Temperature/NCV mode)
Buffer output pin in AZ and ZI phase for ADC_A.
Buffer output pin for ADC_A. Connect to integral resistor
Auto-zero capacitor connection for ADC_A.
Integrator output for ADC_A. Connect to integral capacitor.
Negative connection for reference capacitor of ADC_A.
Positive connection for reference capacitor of ADC_A.
Output of band-gap voltage reference. Typically –1.23V
Positive connection for reference capacitor of ADC_V.
Negative connection for reference capacitor of ADC_V.
Integrator output for ADC_V. Connect to integral capacitor.
Auto-zero capacitor connection for ADC_V.
Buffer output pin for ADC_V. Connect to integral resistor
Buffer output pin in AZ and ZI phase for ADC_V.
Filter capacitor connection1-4 for resistance mode.
Reference input voltage in current mode or ADP. Typically –400mV
DAC output for current mode or ADP input mode
Reference input voltage in voltage mode. Typically –400mV
DAC output for voltage mode
Reference resistor connection for 500.00Ω range
Voltage measurement ÷10000 attenuator(1000V)
Voltage measurement ÷1000 attenuator(500.0V)
Voltage measurement ÷100 attenuator(50.00V)
Voltage measurement ÷10 attenuator(5.000V)
Sense low voltage for resistance/voltage measurement
Measurement Input. Connect to a precise 10MΩ resistor.
DC signal low input in ACV mode. Connect to negative output
of external AC to DC converter.
DC signal high input in ACV mode. Connect to positive output of
external AC to DC converter.
Negative input of internal AC to DC OP Amp for ACV mode.
Output of internal AC to DC OP Amp for ACV mode.
Buffer output of OVSG for ACV mode
Signal Ground.
AC-coupled cap. for ACA Hz mode
AC-coupled cap. for ACA Hz mode
Connect to a 9KΩ resister for duty cycle measurement.
Connect to a 1KΩ resister for duty cycle measurement.
Sense input for resistance measurement
Output connection for resistance measurement
Output connection for resistance measurement (Optional)
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ES51945(5000counts)
Dual Display/No Cap
53
54
55
56
57
58
59
60
61
62
63-86
87-90
91
LPFC1
LPFC2
LPFC3
LPFOUT
SLEEP
BUZIN
FREQ
CAL_EN
SDA
SCL
SEG24-SEG01
BP4-BP1
ALARM
O
O
O
O
O
I
I
I
I/O
O
O
O
O
92
BUZOUT
O
93
BKOUT
O
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115-118
119
120
OSC1
OSC2
LCDCAP
NC
NC
S50V
SVR
APOSEL
NC
CESEL
TSEL
ALARM1
DIS_LPF
DIS_DGB
DIS_DCA
NC
BKLIT
SEL
HOLD
RANGE
SAC
FC4-FC1
CC+
I
O
I
I
I
I
I
I
O
I
I
I
I
I
I
I
I
I
O
O
121
LBAT9
I
122
123
124
125
126
127
128
VVV+
V+
DGND
AGND
AGND
P
P
O
O
P/G
P/G
P/G
v2.3
Capacitor C1 connection for internal low-pass filter
Capacitor C2 connection for internal low-pass filter
Capacitor C3 connection for internal low-pass filter
Capacitor C1 connection for internal low-pass filter
Sleep mode indicator, asserts low in SLEEP mode.
Pull to V- to enable the BUZOUT.
Frequency counter input, offset V-/2 internally by the chip.
Pulled to V- to enable the semi-auto calibration scheme.
Input/Output from/to EEPROM 24C02 data
Output to EEPROM 24C02 clock
LCD segment output driver 01-24 (SEG signals)
LCD backplane 1-4 (COM signals)
LED control output driver for HV indication and NCV detection
Outputs a 2KHz audio frequency signal for driving piezoelectric
buzzer when BUZIN is low or functional key is active.
If BKLIT function is enabled, this pin will change from V- to V+
For 60 sec, once press BKLIT pin again within 60 sec, this pin will
Change back to V-.
Crystal oscillator input connection
Crystal oscillator output connection
LCD bias voltage bypass capacitor connection
Not connected
Not connected
Switch control for function selection
Switch control for function selection
Auto power off idle time selection
Not connected
OL selection feature control pin in Voltage mode.
Pulled to V- to cancel the 500oC auto range mode
LED control output driver for short-circuit detected in Cont. mode.
Pulled to V- to disable the low-pass-filter path in ACA mode
Pulled to V- to disable the buzzer beeper when HV danger appears.
Pulled to V- to disable DCA function in DCV mode.
Not connected
Back light function. Pulse to V- to set BKOUT pin output.
Pulse to V- to enable function selection
Pulse to V- to enable HOLD function.
Pulse to V- to enable manual mode and manual range selection.
Switch for AC/DC function selection.
Switches for function selection.
Negative capacitor connection for on-chip DC-DC converter.
Positive capacitor connection for on-chip DC-DC converter.
Multi-level low battery configuration input. Simple external resistor
divider is required.
Negative supply voltage.
Negative supply voltage.
Output of on-chip DC-DC converter and positive supply voltage.
Output of on-chip DC-DC converter and positive supply voltage.
Digital ground.
Analog ground.
Analog ground.
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ES51945(5000counts)
Dual Display/No Cap
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- = -3.0V
Parameter
Power supply
Operating supply current
In DCV+DCA mode
Voltage roll-over error
Voltage nonlinearity
Symbol
Test Condition
VNormal operation
IDD
In sleep mode
ISS
REV 10MΩ input resistor
Best case straight
NLV
line
Input Leakage
Zero input reading
Band-gap reference voltage
VREF
Open circuit voltage for 500Ω
measurement
Open circuit voltage for other Ω
measurement
Peak to peak backplane
drive voltage
10MΩ input resistor
100KΩ resistor
between VRH and
AGND
-3.5V≤ V- ≤-2.5V
Min.
-2.5
—
—
—
Typ.
-3.0
1.9
5
—
Max
-3.5
2.2
10
±0.1
Units
V
mA
µA
%F.S1
—
—
±0.1
%F.S1
-10
-000
1
000
10
+000
PA
counts
-1.29
-1.23
-1.17
V
—
-3.0
—
V
-1.19
-1.08
-0.97
V
2.9
3.1
3.3
V
—
1.2
—
µA
—
—
—
—
40-400
400-2000
2.15
1.82
—
—
—
—
Pin97-118 inputs
Internal pull-high to 0V
current
Ipull-up
AC frequency response at 5.000V
range
±1%
±5%
Multi-level low battery detector
Vt1
Vt2
LBAT9 vs. V-
3dB Bandwidth for ACA mode
f3dB
Low-pass-filter ON
Reference voltage temperature
coefficient
TCRF
100KΩ resister
between VRH/GND
0℃<TA<70℃
4
—
100
HZ
V
kHz
—
ppm/℃
Note:
1. Full Scale
v2.3
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10/06/25
ES51945(5000counts)
Dual Display/No Cap
Function Description
1. Dual Display
1.1 Introduction
ES51945 configures a dual display LCD driver for DMM applications. The dual display
includes first-display and second-display. Each display has 4 digits to show up to 5000
counts. The simplified representation of dual display is shown below. First-display usually
shows Volts readings in ACV/DCV mode or Hz readings in Frequency mode.
Second-display usually shows Amps/Hz readings in ACA/DCA mode or Duty-cycle
readings in Frequency mode. By the dual display feature, ES51945 can shows Amps and
Volts readings at the same time. Other features achieved by dual display will be introduced
in later sections. The full LCD configuration is shown at section 3.4 of page 23.
Second Display
A
First Display
V
v2.3
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ES51945(5000counts)
Dual Display/No Cap
1.2 Dual display V.S. measurement mode
The dual display default mode configuration is shown at the table below.
Main measurement mode
DC voltage
AC voltage
NCV mode
Resistance mode
Frequency mode
Continuity Check
Diode mode
Temperature mode
DCuA mode
First-display
DC voltage
AC voltage
EF
Resistance
Frequency
Resistance
Voltage
o
C
N/A
Second-display (defaulted)
N/A
N/A
Electrical field strength
N/A
Duty cycle
N/A
N/A
o
F
DCuA
1.3 Push key operation
With dual display, user can use single push key “SEL” to active the Volts and Amps
readings simultaneously.
Push function
First-display
Second-display
SEL in DCV mode
DC Voltage
DCA1 Æ DCA/Zero2
(function selection)
See Fig.1
SEL in ACV mode
AC Voltage
ACA ÅÆ ACA Hz3
(function selection)
See Fig.2
Hold
Stop updating
Stop updating
NOTE:
1.
DCA mode is not available if DIS_DCA (pin108) is pulled to V-.
2.
DCA/Zero means the readings shown on LCD is offset-cancelled readings.
3.
Hz mode is the frequency reading of ACA mode.
v2.3
7
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ES51945(5000counts)
Dual Display/No Cap
Fig.1 SEL key operation in DCV + DCA(zero) mode
DCV
DCV+DCA
DCV+DCA ZERO
DC
DC
DC
0.0 5
Push <1S
AUTO
A
4.8 9 9
A
4.8 9 9
V
AUTO
4.8 9 9
V
0.0 0
Push <1S
AUTO
ZERO
V
Push >1S
Fig. 2 SEL key operation in ACV + ACA(Hz) mode
ACV
ACV+ACA
ACV+Hz of ACA
AC
AC
AC
Push <1S
AUTO
2 1 9.9
9 0.9 3
A
AUTO
V
2 1 9.9
Push <1S
6 0.0
Hz
AUTO
V
2 1 9.9
V
Push >1S
High Voltage warning
v2.3
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ES51945(5000counts)
Dual Display/No Cap
2.
Operating Modes
2.1. Semi-auto calibration scheme
ES51945 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. ES51945 provide another
calibration scheme and the variable resistors could be ignored. When ES51945 is at
OFF-state, pull CAL_EN (pin 60) to V- to active the calibration scheme after re-power on.
A digital controlled voltage output will be active from DAC_AO & DAC_VO. When
semi-auto calibration scheme is active, use HOLD (or BKLIT) key to decrease voltage and
use RANGE 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 BKLIT) and RANGE larger than one second to speed up to
approximate 30 counts per second. After calibration process is finished, push HOLD (or
BKLIT) and RANGE (less than one second) simultaneously to save the digital control code
to external EEPROM (24C02).
HOLD or BKLIT
RANGE
Display Count Up
Display Count Down
HOLD + RANGE
BKLIT + RANGE
v2.3
Save Calibration data to EEP
EEPROM
ROM
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10/06/25
ES51945(5000counts)
Dual Display/No Cap
The semi-auto calibration scheme supports the following seven measurement modes. When
CAL_EN pin is active, set the proper function switches and push SEL key to choose the
target measurement mode. When mode is selected, the LCD segment of Unit at related
measurement will be blinking.
Mode
DC Voltage measurement
AC Voltage measurement
Default range for CAL
Remark
Accuracy of other
5.000V
ranges is guaranteed by
external resistor
Lower range in auto
50.00A or 500.0A or 5000A
ACA mode
500uA or 5000uA
Lower range in Auto
500.0oC or 5000 oC
Temperature mode
DC Current measurement
AC Current measurement
DC uA measurement
Temperature measurement
After calibration procedure is finished, set the ES51945 to OFF-state and set CAL_EN
to DGND to return to normal mode operation after re-power on.
2.2. 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
1
VR1
VR2
VR3
VR4
VR5
Full Scale Range
500.0mV
5.000V
50.00V
500.0V
1000V
Divider Ratio
1
1/10
1/100
1/1000
1/10000
Resister Connection
VR1 (10MΩ)
VR2 (1.111MΩ)
VR3 (101KΩ)
VR4 (10.01KΩ)
VR5 (1KΩ)
Note:
1.
500.0mV range only exists in manual mode.
2.2.1 CE selection & high voltage (HV) indication
ES51945 has a CE selection feature archived by configuring the pin CESEL. In automatic voltage mode,
ES51945 will show OL when the voltage is over than the overflow level. If CESEL is connected to V- or
DGND, ES51945 will have a 610.0V or 1010V overflow level in voltage mode relatively.. The configuration
of CESEL is listed below.
For fully automatic voltage modes:
CESEL
VDGND or floating
v2.3
DCV
610V
1010V
10
ACV
610V
1010V
10/06/25
ES51945(5000counts)
Dual Display/No Cap
During voltage measurement is in operation (DCV or ACV), the HV indication will be
active when input voltage is larger than 30V or OL in manual range. The HV indication
includes:
z HV warning LCD segment active
z Buzzer output active if DIS_DGB (pin107) is kept floating
z ALARM (pin91) LED output active.
2.2.2 NCV mode
ES51945 supports a non-contact AC voltage measurement, which is called electric field
measurement also. The EF mode is selected by setting function control mode FC1-FC4 =
[1,0,0,1]. The ADC input is configured from ADP pin vs. SGND. When no or less electric
field is detected, the first-display LCD shows “EF” and the second-display LCD shows
“Blank”. If the electric field is detected, the strength will be showed on the second-display
LCD by “-“ not digits type. Level 1(equivalent to 12.5% full scale of ADC) is “-“ and the
level 4(equivalent to 100% full scale of ADC) is “----“. Additional beeper (BUZOUT pin)
and LED alarm (ALARM pin) will be output from ES51945. The frequency of buzzer and
LED alarm depends on the strength of electric field also. The Faster beeper means the
stronger electric field (AC voltage) is sensed.
MANU
LEVEL 1 (12.5%)
LEVEL 2 (25%)
LEVEL 3 (50%)
-
--
---
EF
MANU
MANU
EF
EF
LEVEL 4 (100%)
---MANU
EF
EF test circuit
100k
EFin+
ADP
88M
EFin-
SGND
AGND
-400mV
v2.3
VA-
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ES51945(5000counts)
Dual Display/No Cap
2.3 Current measurement for clampmeter
(1) ACA/DCA
ES51945 has 2 automatic and 3 manual current measurement modes for Clampmeter.
The following table summarizes the full-scale range of each mode. When ES51945
operate in the automatic VA1 ~ VA2, it takes high input from IVSH/IVSL (higher
range/lower range), low input from SGND and reference voltage from VR_A (pin29).
When ES51945 operates in the manual VA3 ~ VA5, It takes high input from ADP, low
input from SGND and reference voltage from VA- (pin8).
Mode
VA1
VA2
VA3
VA4
VA5
FC1~4
0,0,0,0
0,0,0,1
0,1,0,0
0,1,0,1
0,1,1,0
Full Scale
50.00A / 50.00A
500.0A / 5000A
50.00A
500.0A
5000A
Input Terminal
IVSL/IVSH V.S. SGND (500mV)
IVSL/IVSH V.S. SGND (500mV)
ADP V.S. SGND (500mV)
ADP V.S. SGND (500mV)
ADP V.S. SGND (500mV)
Note:
1. In DCA current modes (SAC = 0) , ES51945 provides Zero function (push SEL key) for offset removing.
(2) DCuA mode
ES51945 has 2 manual DCuA current measurement modes for flame rod application.
The following table summarizes the full scale range of each mode.
Mode
DCuA1
DCuA2
FC1~4
0,0,1,0
0,0,1,1
Full Scale
500.0uA
5000uA
Input Terminal
ADP V.S. SGND (500mV)
ADP V.S. SGND (500mV)
(3) Low pass filter (LPF) mode for ACA mode
A 3rd order low-pass filter (3dB bandwidth = 4kHz typ.) with is built in ES51945 to
reduce the influence of high frequency noise. The LPF mode is active in ACA only if
DIS_LPF is connected to DGND or floating.
v2.3
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ES51945(5000counts)
Dual Display/No Cap
2.4 Resistance Measurement ( R )
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.
Configuration
OR1
OR2
OR3
OR4
OR5
OR6
Full Scale Range
500.0Ω
5.000KΩ
50.00KΩ
500.0KΩ
5.000MΩ
50.00MΩ
Relative Resistor
OR1
VR5
VR4 || VR1
VR3 || VR1
VR2 || VR1
VR1
Equivalent value
100Ω
1KΩ
10KΩ
100KΩ
1MΩ
10MΩ
2.5 Continuity Check ( S )
Continuity check shares the same configuration with 500.0Ω manual resistance
measurement mode and has buzzer output to indicate continuity. The buzzer generates
2KHz beep and ALARM1 (pin 105) drive high output (V+ level) whenever the reading is
less than 30Ω. The ES51945 built in a high speed short detection circuit and the detection
could be less than 10ms.
2.6 Diode Measurement ( D )
Diode measurement mode shares the same configuration with 5.000V manual voltage
measurement mode and has buzzer output to indicate continuity. The buzzer generates a
2KHz sound and Alarm1 (pin 105) drive high output (V+ level) whenever the reading is less
than 30mV. If the test circuit is open or the voltage drop between the two ports of the diode
under test is larger than 2V, the LCD panel will show “OL”.
2.7 Frequency counter
In frequency mode, main-display shows frequency and sub-display shows duty cycle at the
same time. The time base of the frequency counter is derived from an external crystal
oscillator by
Tcounter =
v2.3
4,000,000
Fosc
13
10/06/25
ES51945(5000counts)
Dual Display/No Cap
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 500.0Hz
to 50.00MHz. The following table summarizes the full-scale range of the frequency counter.
Configuration
FR1
FR2
FR3
FR4
FR5
FR6
Full Scale range
500.0Hz
5.000KHz
50.00KHz
500.0KHz
5.000MHz
50.00MHz
*If input frequency is less than 5.0Hz, ES51945 will show 0.0Hz
2.8 Duty Cycle measurement
The duty cycle measurement is available in frequency mode simultaneously. The duty cycle
mode range is available within 5.0% to 95.0% (< 10kHz@3Vpp). The minimum resolution
is 0.1%. If the source frequency duty cycle is smaller than 1.0%, the 0.0% will be shown on
the LCD display. If the duty cycle is larger than 98.9%, the OL will be shown on the LCD
sub-display. When the frequency is zero, the duty cycle display will be 0.0%.
FREQ + Duty cycle
5 0.0
%
AUTO
4.0 0 0MHz
2.9 Temperature measurement mode
Temperature measurement mode takes input signal from ADP pin and reference
voltage from VA-. ES51945 has a built-in ºC-to-ºF scale translation circuit, and only needs
an external ºC scale application circuit. The application circuit for ºF scale is not required.
v2.3
14
10/06/25
ES51945(5000counts)
Dual Display/No Cap
The ºC & ºF readings are shown on the dual-display LCD simultaneously. In
temperature2 measurement mode, the default range is 5000 ºC or 9032 ºF manual range. In
temperature1 measurement mode, the default range is 500.0/5000 ºC or 932.0/9032 ºF auto
range. The TSEL pin (pin104) is pulled to V-, the temperature1 measurement mode will be
set to 500.0 ºC manual mode.
Range
Temp1
Temp2
Full scale range
Auto 500.0℃ / 5000℃
Manual 5000℃
Input terminal
ADP V.S. SGND (50mV/500mV)
ADP V.S. SGND (500mV)
2.10 Multi-level low battery voltage detection
ES51945 provides a voltage detection input (pin 121: LBAT9) for multi-level low battery
application. There are two internal voltage reference Vt1 & Vt2 for comparing with LBAT9.
If LBAT9 is larger than Vt1, the LCD segment of SLB3 – SLB1 will active always. This
status implies Full battery. When LBAT9 is less than Vt1 but larger than Vt2, the LCD
segment of SLB3 will disappear and this status implies Half battery. When LBAT9 is less
than Vt2, the LCD segment of SLB2 will disappear and this status implies Low battery.
When the Low battery status lasts for 10 seconds, the LCD segment of SLB1 will be
blinking. When the SLB1 is blinking for 20 seconds, the operation of meter will be
inhibited and LCD panel will show “ Lo.bt”. In this case, it is suggested to replace a new
battery immediately. After “Lo.bt” appears and lasts for 60 seconds, ES51945 will enter to
auto power off mode.
Full battery
Half battery
Low battery condition > 30s
Operation not allowed
Low battery
blinking
AUTO
AUTO
AUTO
AUTO
DC
DC
DC
DC
1.8 0 0
V
1.8 0 0
V
1.8 0 0
Low battery test circuit (a)
L o.b t
Low battery test circuit (b)
3V
9V
BA
150K
BA
LBAT9
TT
0.1u
470K
910K
LBAT9
TT
AGND
V-
0.1u
300K
0V
v2.3
V
AGND
V-
0V
15
10/06/25
ES51945(5000counts)
Dual Display/No Cap
2.11 Auto power off (APO) and idle time selection
ES51945 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 sign on the LCD panel indicates whether the auto power off is enabled or not. If user
might want to disable Auto power off, power on the meter when any of the push functions,
except for HOLD, is pressed down.
Note:
1.
Powering on the meter while pressing HOLD and lasts 2 seconds turns on all LCD segments until HOLD
is pressed again.
2.
When low battery status happened (LCD show “Lo.bt”), the APO idle time will be reset to 60 sec.
2.12 Sleep
The meter enters sleep mode after auto power off. The SLEEP pin asserts low (V-) in the
sleep mode, and asserts high (V+, not 0V) after re-power on.
2.13 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.
v2.3
16
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ES51945(5000counts)
Dual Display/No Cap
3. Measurement Mode Switching
Measurement mode depends on the logic level of SVR, S50V, SAC, FC1, FC2, FC3 and
FC4.
SVR
S50V
SAC
FC1
FC2
FC3
FC4
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
0
0
0
0
0
1
1
1
1
1
X
X
X
X
X
0
0
0
0
0
1
1
1
1
1
X
X
X
X
X
X
X
X
X
X
X
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
X
X
X
X
0
0
0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
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
0
0
1
1
1
0
0
1
1
1
0
0
1
1
1
0
0
1
1
1
0
0
1
1
1
0
0
1
1
1
0
0
0
0
0
0
1
1
1
1
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
0
0
0
0
1
1
1
0
0
1
1
0
0
1
0
0
0
1
0
1
0
0
1
0
1
0
0
1
0
1
0
0
1
0
1
0
0
1
0
1
0
0
1
0
1
0
0
1
0
1
0
1
0
1
0
0
1
Function mode
ACV (5.000V) + ACA (50.00A / 500.0A)
ACV (5.000V) + ACA (500.0A / 5000A)
ACV (5.000V) + ACA (50.00A)
ACV (5.000V) + ACA (500.0A)
ACV (5.000V) + ACA (5000A)
ACV (50.00V) + ACA (50.00A / 500.0A)
ACV (50.00V) + ACA (500.0A / 5000A)
ACV (50.00V) + ACA (50.00A)
ACV (50.00V) + ACA (500.0A)
ACV (50.00V) + ACA (5000A)
ACV (500.0V) + ACA (50.00A / 500.0A)
ACV (500.0V) + ACA (500.0A / 5000A)
ACV (500.0V) + ACA (50.00A)
ACV (500.0V) + ACA (500.0A)
ACV (500.0V) + ACA (5000A)
DCV (5.000V) + DCA (50.00A / 500.0A)
DCV (5.000V) + DCA (500.0A / 5000A)
DCV (5.000V) + DCA (50.00A)
DCV (5.000V) + DCA (500.0A)
DCV (5.000V) + DCA (5000A)
DCV (50.00V) + DCA (50.00A / 500.0A)
DCV (50.00V) + DCA (500.0A / 5000A)
DCV (50.00V) + DCA (50.00A)
DCV (50.00V) + DCA (500.0A)
DCV (50.00V) + DCA (5000A)
DCV (500.0V) + DCA (50.00A / 500.0A)
DCV (500.0V) + DCA (500.0A / 5000A)
DCV (500.0V) + DCA (50.00A)
DCV (500.0V) + DCA (500.0A)
DCV (500.0V) + DCA (5000A)
DCuA (500.0uA)
DCuA (5000uA)
FREQ + Duty cycle
NCV (EF)
1
Temp (500.0 oC / 5000 oC) (AUTO)
o
Temp (5000 C)
R (Resistance mode)
S (Continuity mode)
D (Diode check mode)
R,S
R,S,D
Remark
VA1
VA2
VA3
VA4
VA5
VA1
VA2
VA3
VA4
VA5
VA1
VA2
VA3
VA4
VA5
VA1
VA2
VA3
VA4
VA5
VA1
VA2
VA3
VA4
VA5
VA1
VA2
VA3
VA4
VA5
DCuA1
DCuA2
Fmode
EFmode
Temp1
Temp2
R
S
D
RS
RSD
X means “don’t care”.
1
50mV full scale is for 500 oC range and 500mV full scale is for 5000 oC range. When TSEL (pin104) is pulled to V-, the 500oC range is
fixed
v2.3
17
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ES51945(5000counts)
Dual Display/No Cap
Push function
All the enabled push functions will be reset when the measurement mode is changed by
rotary switch. The following table lists the available function versus every measurement
mode.
DCV
DCV + DCA
ACV
ACV + ACA
DCuA
Frequency
NCV ( EF )
2
Temp1
Temp2
Resistance
Continuity
Diode
R , S1
R , S1 , D
RANGE
HOLD
SEL
BKLIT
O
O
( V only)
O
O
( V only)
X
O
X
O
X
O
X
X
O
( R only)
O
( R only)
O
O
O
O
O
O
O
O
O
O
O
O
O
O
X
O
O
O
O
O
X
X
X
X
X
X
X
X
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Note:
1
Continuity mode
2
Auto range configuration
v2.3
18
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ES51945(5000counts)
Dual Display/No Cap
3.1. HOLD and Delay Hold feature
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. ES51945 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. HOLD function and the
delayed state can be cancelled by changing the measurement mode, pressing RANGE, or
push HOLD again.
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 configuration is shown below. It is available for voltage, resistance, frequency
and temperature (Temp1) modes.
1 push < 1 sec
Automatic
Mode
Manual
Mode
1 push > 1 sec
Range up
1 push < 1 sec
v2.3
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ES51945(5000counts)
Dual Display/No Cap
Measurement Mode
V(DC/AC)
Auto A(DC/AC)
Auto A(AC/DC)
Auto
Manual
VRi → VRi + 1,
VR2 – VR5
VR5 → VR1
IR1 – IR2
N/A3
IR1－IR2
N/A3
Manual A(AC/DC)
fixed
fixed
Manual DCuA
fixed
fixed
Ω
OR1 – OR6
Continuity
Diode
fixed
fixed
Temp1
T1-T2
Frequency
FR1 – FR6
ORi → ORi + 1,
OR6 → OR1
fixed
fixed
T1 → T2
T2 → T1
FRi → FRi + 1
FR6 → FR1
Control Range
Initial Range
500.0mV – 1000V
5.000V1
500.0A – 5000A
50.00A – 500.0A
50.00A
500.0A
5000A
500.0uA
5000uA
500.0A
50.00A
50.00A
500.0A
5000A
500.0uA
5000uA
500.0Ω – 50.00MΩ
500.0Ω
500.0Ω
5.000V
500.0Ω
5.000V
500.0oC – 5000oC
500.0oC
500.0Hz – 50.00MHz
500.0Hz
Note: Pushing RANGE resets all existing special modes.
1
Initial range depends on status of SVR & S50V. See Measurement Mode Switching
v2.3
20
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ES51945(5000counts)
Dual Display/No Cap
3.3. ZERO function
In manual DC 50.00A, 500.0A and 5000A, auto DC 50.00A/500.0A and auto DC
500.0A/5000A mesurement modes, ES51945 provides Zero function to remove the residual
current value. During DCV and DCA mode are active simultaneously, push SEL key less
than one second to enter Zero mode. In Zero mode, second-display shows DN+K - DN, where
N = 1, 2, 3, … , DN is the last conversion value before SEL is pushed, and DN+K is the
current conversion value. If SEL is pushed again in Zero mode, second-display will update
the DN value and displays the DN+K - DN again. The meter returns to DCV operation only if
SEL is pressed and held for longer than one second. In 2-range auto DCA modes for
clampmeter (500.0A/5000A or 50.00A/500.0A), 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 the range should stay at lower one in automatic mode. When enter
Zero mode in lower range, the system will store the nonzero counts (residual current value).
If the range goes up to higher one automatically, the non-zero counts will be divided by ten.
So this function will still work well in automatic modes.
State diagram for Zero mode:
Original State (DCV only)
Press SEL < 1s
DCV+DCA
Press SEL > 1s
Press SEL < 1s
‘Zero’ Active
Press SEL < 1s
Main-display: DN+K - DN
v2.3
21
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ES51945(5000counts)
Dual Display/No Cap
Miscellaneous
The conditions, 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 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 which 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
v2.3
22
10/06/25
ES51945(5000counts)
Dual Display/No Cap
3.4.
LCD Panel
v2.3
23
10/06/25
ES51945(5000counts)
Dual Display/No Cap
LCD Backplane Waveform
V- +3.1
V- +3.1
V-
V-
V- +3.1
V- +3.1
V-
V-
V- +3.1
V- +3.1
VV- +3.1
VV- +3.1
V-
3.5. LCD display on condition
LCD Annunciator
Condition
V
In voltage measurement mode, and diode measurement mode.
A
In current measurement mode.
Ω
In resistance measurement mode, and continuity mode.
In continuity check mode.
In diode mode.
%
In duty cycle measurement.
Hz
Hz for Frequency mode (voltage signal to FREQ input)
Hz2
Hz for ACA mode (ADP/IVSH/IVSL)
DC
In DC voltage or current mode.
AC
In AC voltage or current mode.
AUTO
When automatic range selection is enabled. (Voltage, resistance, frequency mode)
MANU
In manual mode.
HOLD
When HOLD function is enabled.
m2
In voltage measurement mode and the full scale range is in the order of 10-3.
In DCuA current measurement mode and the full scale range is in the order of uA.
µ2
M
In resistance measurement mode and the full scale range is in the order of MΩ
K
In resistance measurement mode and the full scale range is in the order of KΩ
When the reading is exceeding 30V or OL in DCV or ACV, the HV warning symbol
will be displayed.
℃
In temperature measurement mode and when the unit is ℃
℉
In temperature measurement mode and when the unit is ℉
SLB3
When voltage (ref. to V-) of LBAT9 pin is less than Vt1, SLB3 will disappear.
SLB2
When voltage (ref. to Vo) of LBAT9 pin is less than Vt2, SLB2 will disappear.
SLB1
When SLB2 disappears for 8 seconds, SLB1 will be blinking.
APO
When auto power off function is enabled.
v2.3
24
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ES51945(5000counts)
Dual Display/No Cap
3.6. Operating Timing
ES51945 incorporates a dual slope ADC with four phases: ZI, AZ, INT and DINT. The
timing of each phase is listed below.
*Voltage / Current / Ohm / ADP / Temperature (High range) measurement:
Phase
ZI
AZ
INT
DINT
Period
50ms
24ms
100ms
126ms
* Temperature mode (Low range: 500oC mode)
Phase
ZI
AZ
INT
DINT
Period
50ms
24ms
1000ms
126ms
*Frequency + Duty cycle mode measurement
In range 500.0Hz~50MHz, 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 ten times and the new measurement cycle becomes 1/10 times of
the original cycle until the range is stable.
v2.3
25
10/06/25
1
ADO_A
ADI_A
TEST5A
ACVLA
ACVHA
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHMC4
OHMC3
OHMC2
OHMC1
VR_A
DACAO
VR
DACVO
OR1
VR5
VR4
VR3
VR2
OVSG
V+ V-
2
DIS_DCA
DIS_DGBP
DIS_LPF
ALARM1
TSEL
CESEL
NC
APOSEL
SVR
S50V
NC
NC
LCDCAP
OSC2
OSC1
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
NC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
V-
U?
3
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
ES51945
R22
47K
5
6
7
8
+
2.2uF
C4
APOSEL
SVR
S50V
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
U2
SDA
SCL
WP
VCC
24C02
4
3
2
1
V-
V-
4MHz
0.1uF
Y1
GND
A2
A1
A0
R25 2.2K PTC
1
J4
Q10 C1815
BKLIT
HOLD
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
Fin
BKOUT
D3
LED
SW5
SW6
SW7
SW8
SW2
SW3
SW11
SW12
SW13
SW14
SW15
4
V-
100
R30 10K
R9
R6 100K
BKLIT
HOLD
V-
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
BZOUT
VQ11
C1815
ALARM
D1
LED
ALARM1
D2
LED
Hi-Z
R7
R1 100K
100
100
5
ADI_A
V-
V-
Q1
C1815
Q2
C1815
C34 22uF
+ VS
R32
+ VS
C30
10uF
C31
+
C35 22uF
R33
+ VS
10uF
C33
+
+ VS
C32
B
Size
Title
10uF
- VS
ADI_V
10uF
- VS
R8
R2 100K
V-
BZ1
Buzzer
R31 10K
TRMS Circuit
Q12
KN2907
- VS
200K
- VS
200K
1
2
3
4
5
6
7
1
2
3
4
5
6
7
C36
SW1
10uF
Power Switch
5.6V
0.1uF
14
13
12
11
10
9
8
14
13
12
11
10
9
8
6
2.2uF
+ C39
V-
ACVH_V
+ VS
2.2uF
+ C38
ACVH_A
+ VS
ZR2 7.5V
V+
0.1uF
10uF
Bat-
C6
3.3uF
C5
C9
C8
ZR1
Bat+ DC3.0V
U3
3.3uF
Vin
+ VS
En
NC
- VS
NC
CAV
NC
dB
COMMON
BUF out
RL
BUF in
Iout
C37
ES636 (BIN 6)
U4
Vin
+ VS
En
NC
- VS
NC
CAV
NC
dB
COMMON
BUF out
RL
BUF in
Iout
ES636 (BIN 6)
Sheet of
Drawn By:
6
Revision
ES51945_RMS Circuit
8-Jun-2010
F:\Protel file\KA030.ddb
Number
+
SW4
CAL_En
200 C29
Semi-Auto Calibrate
Active Mode to V Normal Mode to GND
R29
C1815
Date:
File:
+
C25
Q9
+
C27
Q8
C1815
5
+
1uF
R21 9K
180K
2K
2K
C26
220pF
Close to IC
Q7
C1815
4
+
ACVH_A
10nF
ADI_A
C1
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
29
30
31
32
33
34
35
36
37
38
Detailed
C22
R20 1K
R26
R27
R28
C1815
3
+
+
+
Metallized Polypropylene Film Capacitor : C11, C12
IVSL
IVSH
ADP
100K
100K
100K
0
470K
220nF
220nF
220nF
100
1K
10.0K
101K
1.111M
220nF
220nF
360K
120K
22n
47n
220nF
470n
VRH
100nF
R3
R4
R5
R10
R11
C10
C11
C15
C16
Detailed
C12
C13
R12
R13
C17
C18
C14
C19
R14
R15
R16
R17
R18
10M
Q5
C1815
Q6
0 ~ 100pF
2
+
D
C
C21
1uF
Gnd
Vin
R19
Bottom Ground Plane
SW10 ACV RMS
VR1
1
J1
1
J2
C1815
FC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
39
40
41
42
43
44
45
46
C3
470nF 47
48
49
50
51
52
C23 1nF
53
C24
220pF 54
C28 4.7nF
55
56
SLEEP
57
BUZIN
58
59
CAL_EN 60
SDA
61
SCL
62
SEG23
63
SEG22
64
C20
1uF
SW9
SW_RC
R23 2.2K PTC
R24 2.2K PTC
Q3
C1815
Q4
LBAT9
C2
470nF
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
AGND
AGND
DGND
V+
V+
VVLBAT 9
C+
CFC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
NC
DISDCA
DISDGB
DIS_LPF
ALARM1
TSEL
CESEL
VR1
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5V
SGND
CACA+
R9K
R1K
OVX
OVH
OVH1
LPC1
LPC2
LPC3
LPFOUT
SLEEP
BUZIN
FREQ
CAL_EN
SDA
SCL
SEG23
SEG22
ACVH_V
ADI_V
Ver:4
D
C
B
A
10/06/25
26
v2.3
B
A
1
+
ES51945(5000counts)
Dual Display/No Cap
4. Application Circuit
4.1 EEPROM is used (AC RMS circuit)
0 ~ 100pF
+
C1
100K
100K
100K
0
470K
220nF
220nF
220nF
ADO_A
ADI_A
TEST5_A
ACVL_A
ACVH_A
10nF
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
29
30
31
32
33
34
35
36
37
38
ADO_A
ADI_A
TEST5A
ACVLA
ACVHA
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHMC4
OHMC3
OHMC2
OHMC1
VR_A
DACAO
VR
DACVO
OR1
VR5
VR4
VR3
VR2
OVSG
V+ V-
2
C27
C25
+
220pF
DIS_DCA
DIS_DGBP
DIS_LPF
ALARM1
TSEL
CESEL
SW4
CAL_En
NC
APOSEL
SVR
S50V
NC
NC
LCDCAP
OSC2
OSC1
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
NC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
V-
200 C29
Semi-Auto Calibrate
Active Mode to V Normal Mode to GND
R29
U1
3
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
ES51945
R22
47K
5
6
7
8
2.2uF
C4
APOSEL
SVR
S50V
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
Q9
V-
V-
1
J4
Q10 C1815
4
3
2
1
4MHz
0.1uF
Y1
GND
A2
A1
A0
C1815
R25 2.2K PTC
24C02
SDA
SCL
WP
VCC
U2
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
Q8
C1815
BKLIT
HOLD
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
Fin
BKOUT
D3
LED
SW5
SW6
SW7
SW8
SW2
SW3
SW11
SW12
SW13
SW14
SW15
4
V-
100
R30 10K
R9
R6 100K
BKLIT
HOLD
V-
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
BZOUT
VQ11
C1815
ALARM
D1
LED
ALARM1
D2
LED
Hi-Z
R1 100K
R7
100
5
3.9K
V-
V-
1uF
+ C32
1uF
+ C34
B
Size
Title
1N4148
D6
3.9K
1N4148
D4
100
R36
R34
15K
R37
R32
15K
R8
R2 100K
V-
BZ1
Buzzer
R31 10K
Average Circuit
Q12
KN2907
Date:
File:
Q1
C1815
Q2
C1815
ADO_V
C35
1uF
10K
C33
1uF
10K
C6
Bat-
SW1
Power Switch
5.6V
0.1uF
6
V-
ACVL_A
C31
0.1uF
ACVH_A
ADI_A
TEST5_A
ACVL_V
C30
0.1uF
ACVH_V
ADI_V
TEST5_V
ZR2 7.5V
V+
0.1uF
10uF
10uF
C36 4.7uF
56K
56K
R42 56K
R35
15K
C37 4.7uF
R41
R40 56K
R33
15K
C5
C9
C8
ZR1
Bat+ DC3.0V
R38
R39
1N4148
D5
D7
ADO_A
1N4148
R43
Sheet of
Drawn By:
6
Revision
ES51945_AVG Circuit
8-Jun-2010
F:\Protel file\KA030.ddb
Number
+
1uF
R21 9K
180K
2K
2K
C26
Close to IC
Q7
C1815
5
+
10M
Detailed
C22
R20 1K
R26
R27
R28
C1815
4
+
100
1K
10.0K
101K
1.111M
220nF
220nF
360K
120K
22n
47n
220nF
470n
VRH
100nF
R3
R4
R5
R10
R11
C10
C11
C15
C16
Detailed
C12
C13
R12
R13
C17
C18
C14
C19
R14
R15
R16
R17
R18
R19
Bottom Ground Plane
Vin
Gnd
Q5
C1815
Q6
3
+
1
IVSL
IVSH
ADP
C21
1uF
VR1
1
J1
1
J2
C1815
0 ~ 100pF
2
+
+
+
Metallized Polypropylene Film Capacitor : C11, C12
C20
1uF
SW9
SW_RC
R23 2.2K PTC
R24 2.2K PTC
Q3
C1815
Q4
FC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
39
40
41
42
43
44
45
46
C3
470nF 47
48
49
50
51
52
53
C23 1nF
C24
220pF 54
55
C28 4.7nF
56
SLEEP
57
BUZIN
58
59
CAL_EN 60
SDA
61
62
SCL
SEG23
63
64
SEG22
D
C
B
A
1
LBAT9
C2
470nF
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
AGND
AGND
DGND
V+
V+
VVLBAT9
C+
CFC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
NC
DISDCA
DISDGB
DIS_LPF
ALARM1
TSEL
CESEL
VR1
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5V
SGND
CACA+
R9K
R1K
OVX
OVH
OVH1
LPC1
LPC2
LPC3
LPFOUT
SLEEP
BUZIN
FREQ
CAL_EN
SDA
SCL
SEG23
SEG22
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5_V
Ver:4
D
C
B
A
10/06/25
27
v2.3
+
ES51945(5000counts)
Dual Display/No Cap
4.2 EEPROM is used (AC AVG circuit)
0 ~ 100pF
+
1
+
10K
C7
R33
IVSL
IVSH
ADP
ACVH_A
10nF
ADI_A
C1
VRH_A
100K
100K
100K
0
470K
220nF
220nF
220nF
VRH
100nF
R3
R4
R5
R10
R11
C10
C11
C15
C16
ADO_A
ADI_A
TEST5A
ACVLA
ACVHA
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHMC4
OHMC3
OHMC2
OHMC1
VR_A
DACAO
VR
DACVO
OR1
VR5
VR4
VR3
VR2
OVSG
2
V+ V-
1uF
C25
+
220pF
DIS_DCA
DIS_DGBP
DIS_LPF
ALARM1
TSEL
CESEL
R29
3
NC
APOSEL
SVR
S50V
NC
NC
LCDCAP
OSC2
OSC1
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
NC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
200 C29
U1
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
ES51945
2.2uF
C4
APOSEL
SVR
S50V
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
C1815
V-
BZOUT
Q10 C1815
1
J4
4MHz
0.1uF
Y1
R25 2.2K PTC
Q9
BKLIT
HOLD
4
BKOUT
D3
LED
SW15
SW14
SW13
SW12
SW11
SW3
SW2
SW8
SW7
SW6
SW5
R30 10K
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
Fin
R6 100K
R9
V-
Q12
KN2907
BKLIT
HOLD
V-
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
100
VQ11
C1815
V-
BZ1
Buzzer
R31 10K
Hi-Z
ALARM
D1
LED
5
VR4
VR3
ALARM1
D2
LED
C30 22uF
TRMS Circuit
ADI_A
+ VS
C21
+
- VS
C20
10uF
C32 22uF
10uF
C36
+
+ VS
10uF
ADI_V
C35
- VS
10uF
R1 100K
R7
R8
R2 100K
200
+ VS
R35
200
R37
+ VS
Title
B
Size
100
100
- VS
200K
- VS
200K
V-
V-
1
2
3
4
5
6
7
1
2
3
4
5
6
7
Q1
C1815
Q2
C1815
U2
C31
R36
10K
10K
C6
6
SW1
Power Switch
5.6V
10uF
0.1uF
+
+
6
Revision
V-
Ver:4
ACVH_V
ACVH_A
ZR2 7.5V
V+
0.1uF
10uF
Bat-
+ VS
+ VS
200
R41
14
13
12
11
10
9
8
200
R38
14
13
12
11
10
9
8
C5
C9
C8
ZR1
Bat+ DC3.0V
3.3uF
500K
3.3uF
- VS
Vin
+ VS
En
NC
- VS
NC
CAV
NC
dB
COMMON
BUF out
RL
BUF in
Iout
ES636
C33
VR5
+ VS
U3
R40
500K
- VS
Vin
+ VS
En
NC
- VS
NC
CAV
NC
dB
COMMON
BUF out
RL
BUF in
Iout
ES636
VR6
+ VS
Sheet of
Drawn By:
ES51945_RMS Circuit
20-Nov-2009
F:\Protel file\KA030.ddb
Number
+
C27
Q8
C1815
+
R21 9K
180K
2K
2K
C26
Close to IC
Q7
C1815
Date:
File:
+
27K
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
29
30
31
32
33
34
35
36
37
38
Detailed
C22
R20 1K
R26
R27
R28
C1815
5
+
4.7uF
220nF
220nF
360K
120K
22n
47n
220nF
470n
VRH_A
VRH_V
100
1K
10.0K
101K
1.111M
10M
Q5
C1815
Q6
4
+
Metallized Polypropylene Film Capacitor : C11, C12
VR1
R22
27K
VRH_A
10K
VRH_V
Detailed
C12
C13
R12
R13
C17
C18
C14
C19
R14
R15
R16
R17
R18
Gnd
Vin
R19
Bottom Ground Plane
SW10 ACV RMS
VR1
1
J1
1
J2
C1815
3
+
D
C
VR2
R32
27K
SW9
SW_RC
R23 2.2K PTC
R24 2.2K PTC
Q3
C1815
Q4
2
2.2uF
FC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
39
40
41
42
43
44
45
46
C3
470nF 47
48
49
50
51
52
C23
1nF 53
C24
220pF 54
55
4.7nF
56
57
SLEEP
BUZIN
58
59
60
61
62
63
SEG23
64
SEG22
C28
C34
2.2uF
C37
LBAT9
C2
470nF
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
AGND
AGND
DGND
V+
V+
VVLBAT 9
C+
CFC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
NC
DISDCA
DISDGB
DIS_LPF
ALARM1
TSEL
CESEL
VR1
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5V
SGND
CACA+
R9K
R1K
OVX
OVH
OVH1
LPC1
LPC2
LPC3
LPFOUT
SLEEP
BUZIN
FREQ
CAL_EN
SDA
SCL
SEG23
SEG22
ACVH_V
ADI_V
D
C
B
A
10/06/25
28
v2.3
B
A
1
+
ES51945(5000counts)
Dual Display/No Cap
4.3 EEPROM is not used (AC RMS circuit)
0 ~ 100pF
0 ~ 100pF
+
+
1
+
10K
C7
R33
IVSL
IVSH
ADP
27K
C1
VRH_A
100K
100K
100K
0
470K
220nF
220nF
220nF
ADO_A
ADI_A
TEST5_A
ACVL_A
ACVH_A
10nF
VRH
100nF
R3
R4
R5
R10
R11
C10
C11
C15
C16
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
29
30
31
32
33
34
35
36
37
38
ADO_A
ADI_A
TEST5A
ACVLA
ACVHA
CSH+
CSHVAIVSL
IVSH
ADP
RAZ_A
BUF_A
CAZ_A
CINT_A
CLN_A
CLP_A
VRH
CLP_V
CLN_V
CINT_V
CAZ_V
BUF_V
RAZ
OHMC4
OHMC3
OHMC2
OHMC1
VR_A
DACAO
VR
DACVO
OR1
VR5
VR4
VR3
VR2
OVSG
2
V+ VFC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
C27
C25
220pF
Close to IC
DIS_DCA
DIS_DGBP
DIS_LPF
ALARM1
TSEL
CESEL
R29
3
NC
APOSEL
SVR
S50V
NC
NC
LCDCAP
OSC2
OSC1
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
NC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
200 C29
Q7
C1815
U1
102
101
100
99
98
97
96
95
94
93
92
91
90
89
88
87
86
85
84
83
82
81
80
79
78
77
76
75
74
73
72
71
70
69
68
67
66
65
ES51945
2.2uF
C4
APOSEL
SVR
S50V
BKOUT
BZOUT
ALARM
BP1
BP2
BP3
BP4
SEG01
SEG02
SEG03
SEG04
SEG05
SEG06
SEG07
SEG08
SEG09
SEG10
SEG11
Q9
C1815
V-
BZOUT
Q10 C1815
1
J4
4MHz
0.1uF
Y1
R25 2.2K PTC
SEG12
SEG13
SEG14
SEG15
SEG16
SEG17
SEG18
SEG19
SEG20
SEG21
Q8
C1815
BKLIT
HOLD
4
BKOUT
D3
LED
SW15
SW14
SW13
SW12
SW11
SW3
SW2
SW8
SW7
SW6
SW5
R30 10K
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
Fin
R9
R6 100K
V-
Q12
KN2907
BKLIT
HOLD
V-
RANGE
SEL
S50V
SVR
SAC
FC4
FC3
FC2
FC1
100
VQ11
C1815
V-
BZ1
Buzzer
R31 10K
Hi-Z
ALARM
D1
LED
ALARM1
D2
LED
10K
Average Circuit
VR3
+ C20
1uF
R34
15K
D4
1N4148
VR4
+ C31
10K
1N4148
1uF
R39
15K
D6
5
R7
R1 100K
R8
R2 100K
ADO_V
D5
100
100
R36
1N4148
R41
V-
V-
10K
C21
1uF
10K
C32
1uF
Q1
C1815
Q2
C1815
C30 4.7uF
R37
15K
56K
R38 56K
R43
C33 4.7uF
R42
15K
56K
R44 56K
R45
Bat+ DC3.0V
ZR1
C8
C6
C5
C9
TEST5_V
ADI_V
ACVH_V
ACVL_V
C34
0.1uF
TEST5_A
ADI_A
ACVH_A
ACVL_A
C35
0.1uF
Bat-
6
SW1
10uF
Power Switch
5.6V
0.1uF
6
Revision
V-
Ver:4
ZR2 7.5V
V+
0.1uF
10uF
Sheet of
Drawn By:
ES51945_AVG Circuit
20-Nov-2009
F:\Protel file\KA030.ddb
Number
1N4148
D7
ADO_A
Title
B
Size
Date:
File:
+
R21 9K
1uF
2K
2K
C26
180K
+
Detailed
C22
R20 1K
R26
R27
R28
C1815
5
+
4.7uF
220nF
220nF
360K
120K
22n
47n
220nF
470n
VRH_A
VRH_V
100
1K
10.0K
101K
1.111M
10M
Bottom Ground Plane
R19
Vin
Gnd
Q5
C1815
Q6
4
+
VRH_A
10K
VRH_V
Detailed
C12
C13
R12
R13
C17
C18
C14
C19
R14
R15
R16
R17
R18
VR1
1
J1
1
J2
C1815
3
+
Metallized Polypropylene Film Capacitor : C11, C12
VR1
R22
27K
VR2
R32
27K
SW9
SW_RC
R23 2.2K PTC
R24 2.2K PTC
Q3
C1815
Q4
2
+
D
C
B
A
1
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5_V
D
C
B
A
10/06/25
29
v2.3
LBAT9
C2
470nF
128
127
126
125
124
123
122
121
120
119
118
117
116
115
114
113
112
111
110
109
108
107
106
105
104
103
AGND
AGND
DGND
V+
V+
VVLBAT9
C+
CFC1
FC2
FC3
FC4
SAC
RANGE
HOLD
SEL
BKLIT
NC
DISDCA
DISDGB
DIS_LPF
ALARM1
TSEL
CESEL
VR1
ACVL_V
ACVH_V
ADI_V
ADO_V
TEST5V
SGND
CACA+
R9K
R1K
OVX
OVH
OVH1
LPC1
LPC2
LPC3
LPFOUT
SLEEP
BUZIN
FREQ
CAL_EN
SDA
SCL
SEG23
SEG22
39
40
41
42
43
44
45
46
C3
470nF 47
48
49
50
51
52
C23
1nF 53
C24
220pF 54
4.7nF
55
56
SLEEP
57
BUZIN
58
59
60
61
62
SEG23
63
SEG22
64
C28
+
ES51945(5000counts)
Dual Display/No Cap
4.4 EEPROM is not used (AC AVG circuit)
0 ~ 100pF
0 ~ 100pF
+
ES51945(5000counts)
Dual Display/No Cap
5. Package Information
8.1
128L LQFP Outline drawing
8.2
Dimension parameters
v2.3
30
10/06/25