ICL7139CPL 데이터 시트보기 (PDF) - Intersil
부품명
상세내역
일치하는 목록
ICL7139CPL Datasheet PDF : 13 Pages
| |||
ICL7139, ICL7149
TRIPLE CAZ
CINT
POINT
CAZ
RDEINT
CINT
RDEINT
INT V/Ω
RINTV
LOΩ
-
RX
RKNOWN 1
+
LOW Ω
HIΩ
RKNOWN 2
COMMON
-
+
LOW Ω
T
T AZ
DEINT+
AZ
AZ
AZ
-
+
INTEGRATOR
-
+
DEINT+
COMPARATOR
TO LOGIC SECTION
VREF
T = INT + DEINT
AZ = AUTOZERO
INT = INTEGRATE
FIGURE 8. DETAILED CIRCUIT DIAGRAM FOR RATIOMETRIC Ω MEASUREMENT
Ratiometric Ω Measurement
Common Voltage
The ratiometric Ω measurement is performed by first
integrating the voltage across an unknown resistor, RX, then
effectively deintegrating the voltage across a known resistor
(RKNOWN1 or RKNOWN2 of Figure 8). The shunting effect of
RINTV does not affect the reading because it cancels exactly
between integration and deintegration. Like the current mea-
surements, the Ω measurements are split into two sets of
ranges. LO Ω measurements use a 10kΩ reference resistor,
and the full scale ranges are 4kΩ and 40kΩ. HI Ω measure-
ments use a 1MΩ reference resistor, and the full scale ranges
are 0.4MΩ and 4MΩ. The measurement phases and timing
are the same as the measurement phases and timing for DC
current except: 1) During the integrate phases the input volt-
age is the voltage across the unknown resistor RX, and; 2)
During the deintegrate phases, the input voltage is the voltage
across the reference resistor RKNOWN1 or RKNOWN2.
Continuity Indication
When the ICL7139 and ICL7149 are in the LO Ω
measurement mode, the continuity circuit of Figure 9 will be
active. When the voltage across RX is less than approximately
100mV, the beeper output will be on. When RKNOWN is 10kΩ,
the beeper output will be on when RX is less than 1kΩ.
LOΩ
The analog and digital common voltages of the ICL7139 and
ICL7149 are generated by an on-chip resistor/zener/diode
combination, shown in Figure 10. The resistor values are
chosen so the coefficient of the diode voltage cancels the
positive temperature coefficient of the zener voltage. This
voltage is then buffered to provide the analog common and
the digital common voltages. The nominal voltage between
V+ and analog common is 3V. The analog common buffer
can sink about 20mA, or source 0.01mA, with an output
impedance of 10Ω. A pullup resistor to V+ may be used if
more sourcing capability is desired. Analog common may be
used to generate the reference voltage, if desired.
6.7V
5K
80µA
+
+
3V
125K
-
3.1V
ANALOG
-
+
COMMON
P (PIN 10)
-
+
LOGIC
SECTION
DIGITAL
COMMON
P (INTERNAL)
V+
LO BAT
180K
-+
-
0.3V
+
V-
RKNOWN
HIΩ
+-
LOΩ
- VREF
+
V+
BEEPER
OUTPUT
RUNKNOWN RX
COM
+-
VX
2kHz
V+
VX = 100mV
FIGURE 9. CONTINUITY BEEPER DRIVE CIRCUIT
FIGURE 10. ANALOG AND DIGITAL COMMON VOLTAGE
GENERATOR CIRCUIT
Oscillator
The ICL7139 and ICL7149 use a parallel resonant-type
crystal in a Pierce oscillator configuration, as shown in
Figure 11, and requires no other external components. The
crystal eliminates the need to trim the oscillator frequency.
An external signal may be capacitively coupled in OSC IN,
with a signal level between 0.5V and 3VP-P. Because the
3-41
Share Link: 