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PDF ICL7139 Data sheet ( Hoja de datos )
| Número de pieza | ICL7139 | |
| Descripción | (ICL7139 / ICL7149) 33/4 Digit Autoranging Multimeter | |
| Fabricantes | Intersil Corporation | |
| Logotipo |  |
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ICL7139, ICL7149
August 1997
33/4 Digit,
Autoranging Multimeter
Features
Description
• 13 Ranges - ICL7139
The Intersil ICL7139 and ICL7149 are high performance, low
- 4 DC Voltage 400mV, 4V, 40V, 400V
power, auto-ranging digital multimeter lCs. Unlike other
- 1 AC Voltage 400V
autoranging multimeter ICs, the ICL7139 and ICL7149
- 4 DC Current 4mA, 40mA, 400mA, 4A
always display the result of a conversion on the correct
- 4 Resistance 4kΩ, 40kΩ, 400kΩ, 4MΩ
range. There is no “range hunting” noticeable in the display.
• 18 Ranges - ICL7149
- 4 DC Voltage 400mV, 4V, 40V, 400V
- 2 AC Voltage with Optional AC Circuit
m- 4 DC Current 4mA, 40mA, 400mA, 4A
- 4 AC Current with Optional AC Circuit
o- 4 Resistance 4kΩ, 40kΩ, 400kΩ, 4MΩ
.c• Autoranging - First Reading is Always on Correct Range
• On-Chip Duplex LCD Display Drive Including Three Dec-
imal Points and 11 Annunciators
U• No Additional Active Components Required
• Low Power Dissipation - Less than 20mW - 1000 Hour
t4Typical Battery Life
• Display Hold Input
e• Continuity Output Drives Piezoelectric Beeper
• Low Battery Annunciator with On-Chip Detection
e• Guaranteed Zero Reading for 0V Input on All Ranges
The unit will autorange between the four different ranges. A
manual switch is used to select the 2 high group ranges. DC
current ranges are 4mA and 40mA in the low current group,
and 400mA and 4A in the high current group. Resistance
measurements are made on 4 ranges, which are divided into
two groups. The low resistance ranges are 4/40kΩ. The high
resistance ranges are 0.4/4MΩ. Resolution on the lowest
range is 1Ω.
Ordering Information
TEMP.
PART NUMBER RANGE (oC) PACKAGE
PKG. NO.
ICL7139CPL
0 to 70 40 Ld PDIP E40.6
ICL7149CPL
0 to 70 40 Ld PDIP E40.6
ICL7149CM44
0 to 70 44 Ld MQFP Q44.10x10
hPinouts
SICL7139, ICL7149 (PDIP)
TOP VIEW
taPOL/AC 1
aBP2 2
BP1 3
.DV+ 4
V- 5
VREF 6
wLOΩ 7
HIΩ 8
wDEINT 9
COMMON 10
w omINT 1 11
.cINT V/Ω 12
UTRIPLE POINT 13
t4CAZ 14
eCINT 15
eBEEPER OUT 16
hmA/µA 17
SV/Ω/A 18
taHIΩ-DC/LOΩ-AC 19
aHOLD 20
40 ADG3/E3
39 B3/C3
38 F2/DP3
37 G2/E2
36 A2/D2
35 B2/C2
34 F1/DP2
33 G1/E1
32 A1/D1
31 B1/C1
30 F0/DP1
29 G0/E0
28 A0/D0
27 B0/C0
26 LO BAT/V
25 MΩ/µA
24 Ω/A
23 k/m
22 OSC IN
21 OSC OUT
A2/D2
G2/E2
F2/DP3
B3/C3
ADG3/E3
POL/AC
NC
BP2
BP1
V+
NC
ICL7149 (MQFP)
TOP VIEW
44 43 42 41 40 39 38 37 36 35 34
1 33
2 32
3 31
4 30
5 29
6 28
7 27
8 26
9 25
10 24
11 23
12 13 14 15 16 17 18 19 20 21 22
MΩ/µA
Ω/A
k/m
OSC IN
OSC OUT
HOLD
HIΩ-DC/LOΩ-AC
V/Ω/A
mA/µA
BEEPER OUT
NC
www.DCAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
File Number 3088.1
http://www.intersil.com or 407-727-9207 | Copyright © Intersil Corporation 1999
3-33
1 page  
ICL7139, ICL7149
Detailed Description
General
The Functional Block Diagram shows the digital section
which includes all control logic, counters, and display drivers.
The digital section is powered by V+ and Digital Common,
which is about 3V below V+. The oscillator is also in the digi-
tal section. Normally 120kHz for rejection of 60Hz AC inter-
ference and 100kHz for rejection of 50Hz AC should be
used. The oscillator output is divided by two to generate the
internal master clock. The analog section contains the inte-
grator, comparator, reference section, analog buffers, and
several analog switches which are controlled by the digital
logic. The analog section is powered from V+ and V-.
DIGIT 3
LOW
BATT
AC
2
10
a
f g b kΩ MΩ
e d c mAV µA
DP3 DP2 DP1
FIGURE 2. DISPLAY SEGMENT NOMENCLATURE
DC Voltage Measurement
Autozero
Only those portions of the analog section which are used
during DC voltage measurements are shown in Figure 3. As
shown in the timing diagram (Figure 1), each measurement
starts with an autozero (AZ) phase. During this phase, the
integrator and comparator are configured as unity gain buff-
ers and their non-inverting inputs are connected to Common.
The output of the integrator, which is equal to its offset, is
stored on CAZ - the autozero capacitor. Similarly, the offset of
the comparator is stored in ClNT. The autozero cycle equals
1000 clock cycles which is one 60Hz line cycle with a 120kHz
oscillator, or one 50Hz line cycle with a 100kHz oscillator.
Range 1 Integrate
The ICL7139 and ICL7149 perform a full autorange search
for each reading, beginning with range 1. During the range 1
integrate period, internal switches connect the INT V/Ω
terminal to the Triple Point (Pin 13). The input signal is inte-
grated for 10 clock cycles, which are gated out over a period
of 1000 clock cycles to ensure good normal mode rejection
of AC line interference.
TRIPLE
POINT
CAZ
CINT
CAZ
RDEINT
CINT
RDEINT
INT V/Ω
VIN
RINTV
T
T AZ
VREF
DEINT+
AZ
AZ
DEINT-
AZ
DEINT-
VREF
-
+
INTEGRATOR
-
+
DEINT+
COMPARATOR
TO LOGIC SECTION
V+
COMMON
ANALOG
COMMON
V-
6.7V
-
+
80µA
T = (INT)(AR)(AZ)
AR = AUTORANGE CHOPPER
AZ = AUTOZERO
INT = INTEGRATE
FIGURE 3. DETAILED CIRCUIT DIAGRAM FOR DC VOLTAGE MEASUREMENT
3-37
5 Page 
ICL7139, ICL7149
Integrator Capacitor, ClNT
As with all dual-slope integrating convertors, the integration
capacitor must have low dielectric absorption to reduce
linearity errors. Polypropylene capacitors add undetectable
errors at a reasonable cost, while polystyrene and
polycarbonate may be used in less critical applications. The
ICL7139 and ICL7149 are designed to use a 3.3nF
(0.0033µF) ClNT with an oscillator frequency of 120kHz and
an RlNTV of 10MΩ. With a 100kHz oscillator frequency (for
50Hz line frequency rejection), ClNT and RINTV affects the
voltage swing of the integrator. Voltage swing should be as
high as possible without saturating the integrator. Saturation
occurs when the integrator output is within 1V of either V+ or
V-. Integrator voltage swing should be about ±2V when using
standard component values. For different RlNTV and
oscillator frequencies the value of ClNT can be calculated
from:
CINT = (---I--n---t--e---g--(-r--Da----te-e--s---iT--r--ei-m--d---e--I--n)---t-×-e---g-(--Ir--na---t-t-eo---g-r--r-S-a---w-t-e---i-n-C---g--u-)--r--r--e---n----t--)
= -(--1---0----,-0----0---0-----x-----2-----x----O-----s---c---i-l--l-a---(-t-o-2---r-V--P--)--e----r--i-o---d----)----×----0----.-4----V----/--R----I--N-----T---V--
The ideal CAZ is a low leakage polypropylene or Teflon
capacitor. Other film capacitors such as polyester, polysty-
rene, and polycarbonate introduce negligible errors. If a few
seconds of settling time upon power-up is acceptable, the
CAZ may be a ceramic capacitor, provided it does not have
excessive leakage.
Ohm Measurement Resistors
Because the ICL7139 and ICL7149 use a ratiometric ohm
measurement technique, the accuracy of ohm reading is pri-
marily determined by the absolute accuracy of the
RKNOWN1 and RKNOWN2. These should normally be 10kΩ
and 1MΩ, with an absolute accuracy of at least 0.5%.
Current Sensing Resistors
The 0.1Ω and 9.9Ω current sensing resistors convert the
measured current to a voltage, which is then measured
using RlNT l. The two resistors must be closely matched, and
the ratio between RlNT l and these two resistors must be
accurate - normally 0.5%. The 0.1Ω resistor must be capa-
ble of handling the full scale current of 4A, which requires it
to dissipate 1.6W.
Continuity Beeper
Integrator Resistors
The normal values of the RlNT V and RlNT l resistors are
10MΩ and 1MΩ respectively. Though their absolute values
are not critical, unless the value of the current sensing resis-
tors are trimmed, their ratio should be 10:1, within 0.05%.
Some carbon composition resistors have a large voltage
coefficient which will cause linearity errors on the 400V scale.
Also, some carbon composition resistors are very noisy. The
class “A” output of the integrator begins to have nonlinearities
if required to sink more than 70µA (the sourcing limit is much
higher). Because RlNT V drives a virtual ground point, the
input impedance of the meter is equal to RlNT V.
Deintegration Resistor, RDElNT
Unlike most dual-slope A/D converters, the ICL7139 and
ICL7149 use different resistors for integration and deintegra-
tion. RDElNT should normally be the same value as RlNT V,
and have the same temperature coefficient. Slight errors in
matching may be corrected by trimming the reference voltage.
Autozero Capacitor, CAZ
The CAZ is charged to the integrator’s offset voltage during
the autozero phases, and subtracts that voltage from the
input signal during the integrate phases. The integrator thus
appears to have zero offset voltage. Minimum CAZ value is
determined by: 1) Circuit leakages; 2) CAZ self-discharge;
3) Charge injection from the internal autozero switches.
To avoid errors, the CAZ voltage change should be less than
1/10 of a count during the 10,000 count clock cycle integra-
tion period for the 400mV range. These requirements set a
lower limit of 0.047µF for CAZ but 0.1µF is the preferred
value. The upper limit on the value of CAZ is set by the time
constant of the autozero loop, and the 1 line cycle time
period allotted to autozero. CAZ may be several 10s of µF
before approaching this limit.
The Continuity Beeper output is designed to drive a piezo-
electric transducer at 2kHz (using a 120kHz crystal), with a
voltage output swing of V+ to V-. The beeper output off state
is at the V+ rail. When crystals with different frequencies are
used, the frequency needed to drive the transducer can be
calculated by dividing the crystal frequency by 60.
Display
The ICL7139 and ICL7149 use a custom, duplexed drive dis-
play with range, polarity, and low battery annunciators. With
a 3V peak display voltage, the RMS ON voltage will be
2.37V minimum; RMS OFF voltage will be 1.06V maximum.
Because the display voltage is not adjustable, the display
should have a 10% ON threshold of about 1.4V. Most display
manufacturers supply a graph that shows contrast versus
RMS drive voltage. This graph can be used to determine
what the contrast ratio will be when driven by the ICL7139
and ICL7149. Most display thresholds decrease with
increasing temperature. The threshold at the maximum
operating temperature should be checked to ensure that the
“off” segments will not be turned “on” at high temperatures.
Crystal
The ICL7139 and ICL7149 are designed to use a parallel
resonant 120kHz or 100kHz crystal with no additional exter-
nal components. The RS parameter should be less than
25kΩ to ensure oscillation. Initial frequency tolerance of the
crystal can be a relatively loose 0.05%.
Switches
Because the logic input draws only about 5µA, switches
driving these inputs should be rated for low current, or “dry”
operations. The switches on the external inputs must be able
to reliably switch low currents, and be able to handle
voltages in excess of 400VAC.
3-43
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet ICL7139.PDF ] | |
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