TC826 Datasheet, PDF (1/12 Pages) TelCom Semiconductor, Inc – A/D CONVERTER WITH BAR GRAPH DISPLAY OUTPUT

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TC826
A/D CONVERTER WITH BAR GRAPH DISPLAY OUTPUT
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FEATURES
GENERAL DESCRIPTION
s Bipolar A/D Conversion
s 2.5% Resolution
s Direct LCD Display Drive
s ‘Thermometer’ Bar or Dot Display
s 40 Data Segments Plus Zero
s Overrange Plus Polarity Indication
s Precision On–Chip Reference ................ 35ppm/°C
s Differential Analog Input
s Low Input Leakage .......................................... 10pA
s Display Flashes on Overrange
s Display Hold Mode
s Auto–Zero Cycle Eliminates Zero Adjust
Potentiometer
s 9V Battery Operation
s Low Power Consumption ............................ 1.1mW
s 20mV to 2.0 V Full–Scale Operation
s Non–Multiplexed LCD Drive for Maximum
Viewing Angle
PIN CONFIGURATION
64 63 62 61 60 59 58 57 56 55 54 53 52 51 50 49
NC 1
ANALOG
COMMON ²
+IN ₃
– IN 4
REF IN ₅
CR+EF 6
CR–EF ₇
VDD ₈
VBUF ₉
CAZ ₁₀
VINT ₁₁
VSS ₁₂
OSC1 ₁₃
OSC2 14
BP 15
BAR 0 16
TC826CBU
48 NC
47 BAR 30
46 BAR 29
45 BAR 28
44 BAR 27
43 BAR 26
42 BAR 25
41 BAR 24
40 BAR 23
39 BAR 22
38 BAR 21
37 BAR 20
36 BAR 19
35 BAR 18
34 BAR 17
33 BAR 16
17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32
In many applications a graphical display is preferred
over a digital display. Knowing a process or system oper-
ates, for example, within design limits is more valuable than
a direct system variable readout. A bar or moving dot display
3 ^{supplies information precisely without requiring further inter-}
pretation by the viewer.
The TC826 is a complete analog–to–digital converter
with direct liquid crystal (LCD) display drive. The 40 LCD
data segments plus zero driver give a 2.5% resolution bar
display. Full–scale differential input voltage range extends
from 20mV to 2V. The TC826 sensitivity is 500µv. A low drift
35 ppm/°C internal reference, LCD backplane oscillator and
4 ^{driver, input polarity LCD driver, and overrange LCD driver}
make designs simple and low cost. The CMOS design
required only 125µA from a 9V battery. In +5V systems a
TC7660 DC to DC converter can supply the –5V supply. The
differential analog input leakage is a low 10pA.
Two display formats are possible. The BAR mode
display is like a ‘thermometer’ scale. The LCD segment
driver that equals the input plus all below it are on. The DOT
5 ^{mode activates only the segment equal to the input. In either}
mode the polarity signal is active for negative input signals.
An overrange input signal causes the display to flash and
activates the overrange annunciator. A hold mode can be
selected that freezes the display and prevents updating.
The dual slope integrating conversion method with
auto–zero phase maximizes noise immunity and eliminates
zero–scale adjustment potentiometers. Zero–scale drift is a
6 ^{low 5 µV/°C. Conversion rate is typically 5 per second and}
is adjustable by a single external resistor.
A compact, 0.5" square, flat package minimizes PC
board area. The high pin count LSI package makes multi-
plexed LCD displays unnecessary. Low cost, direct drive
LCD displays offer the widest viewing angle and are readily
available. A standard display is available now for TC826
prototyping work.
ORDERING INFORMATION
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Part No.
TC826CBU
Package
64–Pin PFP
Temperature
0°C to +70°C
TELCOM SEMICONDUCTOR, INC.
TC826-6 11/6/96
3-171
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