NJU9214
PRELIMINARY
43/4 DIGIT SINGLE CHIP DIGITAL MULTIMETER LSI
The NJU9214 is a 43/4 digits single chip digital multimeter LSI with
42 segments bargraph display.
The NJU9214 realizes high precision of 40,000 counts measure-
ment by the NJRC original dual-slope A to D converter and realizes
also quick response bargragh display and auto-ranging by another high
speed dual-slope A to D converter.
The input attenuator part is simplified because the resistor for resis-
tance measurement is applied for voltage bleeder resistor.
Furthermore, the NJU9214 realizes root-mean-square measurement
for AC voltage and current by connecting a External RMS-DC Con-
verter, and Data output by the on chip RS-232C interface circuit.
The NJU9214 is suitable for high precision and high performance
multimeter.
PACKAGE OUTLINE
43/4 Digit Display (Available for UP to 39,999 Display)
42 Segments Quick Response Bargraph Display
NJRC Original Dual-Slope A to D Converter (40,000Counts)
High Speed Dual-Slope A to D Converter (400Counts)
Quick Response Auto-Ranging (20times/sec)
Frequency/Capacitance/Tachometer/Adapter Measurement
Root-Mean-Square Measurement by connecting a External RMS-DC Converter
External Relay Driving
Data Memory/Data Hold/Relative Display/MAX, MIN Display
Power-on Initializing
Auto Power-off
Buttery Life Detector
Rotary/Push SW Mode Selection
1/4 Duty LCD Display Driver
Piezo Buzzer Direct Driving
RS-232C Interface
External Reference Input required
Low Operating Current
C-MOS Technology
Package Outline TQFP100
NJU9214FG1
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GENERAL DESCRIPTION
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FEATURES
NJU9214
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FUNCTION DESCRIPTION
Each measurement functions shown below is available with the NJU9214.
T
N
E
M
E
R
U
S
A
E
M
N
O
I
T
C
N
U
F
E
G
N
A
R
l
a
u
n
a
M
/
o
t
u
A
e
g
a
tl
o
V
C
A
/
C
D
V
0
0
0
4
o
t
V
m
0
0
4
e
g
n
a
r
-
5
:l
a
u
n
a
M
/
e
g
n
a
r
-
4
:
o
t
u
A
1
*
t
n
e
r
r
u
C
C
A
/
C
D
A
m
0
0
0
4
o
t
A
m
4
e
g
n
a
r
4
-l
a
u
n
a
M
/
e
g
n
a
r
2
-l
a
u
n
a
M
o
t
u
A
2
*
t
n
e
r
r
u
C
C
A
/
C
D
A
0
4
d
e
x
i
F
(
e
c
n
a
t
s
i
s
e
R
)
0
0
4
M
0
4
o
t
e
g
n
a
r
-
6
:l
a
u
n
a
M
/
e
g
n
a
r
-
6
:
o
t
u
A
)f
(
y
c
n
e
u
q
e
r
F
z
H
k
0
0
0
1
o
t
z
H
0
0
1
e
g
n
a
r
-
5
:
o
t
u
A
)
C
(
e
c
n
a
ti
c
a
p
a
C
0
0
4
o
t
F
n
4
F
e
g
n
a
r
-
6
:l
a
u
n
a
M
/
e
g
n
a
r
-
6
:
o
t
u
A
)
m
p
r
(
o
h
c
a
T
m
p
r
K
0
0
6
o
t
m
p
r
0
0
0
6
e
g
n
a
r
-
3
:
o
t
u
A
)
(
e
d
o
i
D
d
e
x
i
F
)
(
y
ti
u
n
it
n
o
C
d
e
x
i
F
P
D
A
d
e
x
i
F
3
*
*1 400mV range (AC/DC) is selected in only manual range.
*2 4mA-4000mA range has Auto/Manual-2range and Manual-4range mode, each mode
needs its own application circuit.
*3 ADP is applied for C, hfe and other measurement.
The divided voltages which are output from each resistance R1 to R5 shown in following table are supplied to A/
D converter.
In the AC measurement, after the dividing voltage, these output voltages are converted to DC Voltages with the
external RMS/DC converter. This DC voltage is supplied into A/D converter.
10M
resistor for input terminal may be easy to be affected by noises.
Therefore 10M
and peripheral circuits require some protection like shields and so on for stable display.
The resistors for attenuating should be selected with a flat temperature characteristic. Especially, the resistors
(10M
, 10k
, 1k
) for 400V, 4000V ranges should be selected carefully. For example, when 4,000V is input,
0.4mA (4,000V
10M
) flow through 10M
, and the resistor consumes power of 1.6W (4,000V
0.4mA) and the
temperature of the reference resistor.
After measuring at 400V, 4,000V ranges, sometimes the uncorrect value is shown on the display at 4V, 40V
ranges because the value of resister as the attenuator is changed by the temperature.
( 1 - 1 ) Voltage (DCV, ACV) measurements
E
G
N
A
R
E
T
A
R
N
O
I
S
I
V
I
D
)
V
m
0
0
4
(
1
R
1
)
V
4
(
2
R
M
1
M
0
1
/
)
V
0
4
(
3
R
k
0
0
1
M
0
1
/
)
V
0
0
4
(
4
R
K
0
1
M
0
1
/
)
V
0
0
0
4
(
5
R
k
1
M
0
1
/
( 1 )Measurement function
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