TC7136CPL Microchip Technology, TC7136CPL Datasheet - Page 13

• Manufacturer Part Number: TC7136CPL
• Description: IC ADC 3 1/2DGT LOW PWR 40-DIP
• Manufacturer: Microchip Technology

Specifications of TC7136CPL

• Display Type: LCD
• Configuration: 7 Segment
• Digits Or Characters: A/D 3.5 Digits
• Current - Supply: 70µA
• Voltage - Supply: 9V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Through Hole
• Package / Case: 40-DIP (0.600", 15.24mm)
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Interface: -

7.0
7.1
The TC7136/A is designed with true differential inputs
and accepts input signals within the input stage Com-
mon mode voltage range (V
FIGURE 7-1:
In systems where Common mode voltages exist, the
86dB Common mode rejection ratio minimizes error.
Common mode voltages do, however, affect the inte-
grator output level. A worst case condition exists if a
large positive V
negative differential signal. The negative signal drives
the integrator output positive along with V
Figure 7-2.) For such applications, the integrator out-
put swing can be reduced below the recommended 2V
full scale swing. The integrator output will swing within
0.3V of V+ or V- without increased linearity error.
FIGURE 7-2:
© 2005 Microchip Technology Inc.
–
+
V
V
CM
IN
DEVICE PIN FUNCTIONAL
DESCRIPTION
Differential Signal Inputs
V
IN
+
–
+ (Pin 31), V
Input Buffer
CM
Where:
exists in conjunction with a full scale
V+
Source
COMMON MODE VOLTAGE REMOVED IN BATTERY OPERATION WITH
V
Power
COMMON MODE
VOLTAGE REDUCES
AVAILABLE INTEGRATOR
SWING
V-
V
IN
I
C
R
t
I
I
=
I
R
= ANALOG COMMON
= Integration capacitor
= Integration resistor
= Integration time =
GND
I
IN
CM
C
t
I
I
V+
V-
- (Pin 30)
Measured
). The typical range is
(V
System
[
V
COM
CM
GND
–
+
= V
C
Integrator
I
≠ V
IN
[
IN
CM
4000
F
)
OSC
(see
V
I
ANALOG
COMMON
V+
V-
V
BUF
V
REF
V+ – 1V to V- + 1V. Common mode voltages are
removed from the system when the TC7136A operates
from a battery or floating power source (isolated from
measured system), Common mode voltage removed
in battery operation with V
is connected to analog common (V
Figure 7-1).
7.2
The reference voltage can be generated anywhere
within the V+ to V- power supply range.
To prevent rollover type errors being induced by large
Common mode voltages, C
pared to stray node capacitance. The TC7136/A offers
a significantly improved analog common temperature
coefficient. This potential provides a very stable volt-
age, suitable for use as a voltage reference. The
temperature coefficient of analog common is typically
35ppm/°C.
7.3
The analog common pin is set at a voltage potential
approximately 3V below V+. The potential is between
2.7V and 3.35V below V+. Analog common is tied inter-
nally to an N-channel FET, capable of sinking 100μA.
This FET will hold the common line at 3V below V+ if an
external load attempts to pull the common line toward
V+. Analog common source current is limited to 1μA.
Analog common is, therefore, easily pulled to a more
negative voltage (i.e., below V+ – 3V).
TC7136A
C
TC7136
AZ
-
V
REF
V
INT
+
Differential Reference
V
Analog Common (Pin 32)
TC7136/TC7136A
V+
REF
+
Segment
9V
Drive
+ (Pin 36), V
POL
OSC1
OSC3
OSC2
V-
BP
IN
= analog common and V
REF
LCD
REF
should be large com-
- (Pin 35)
DS21461C-page 13
COM
) (see
IN
-