tc7107a Microchip Technology Inc., tc7107a Datasheet - Page 19

• Manufacturer Part Number: tc7107a
• Description: 3-1/2 Digit Analog-to-digital Converters
• Manufacturer: Microchip Technology Inc.

10.0
10.1
Several manufacturers supply standard LCDs to inter-
face with the TC7106A 3-1/2 digit analog-to-digital
converter.
10.2
Several LED manufacturers supply seven segment
digits with and without decimal point annunciators for
the TC7107A.
10.3
The TEST pin is connected to the internally generated
digital logic supply ground through a 500Ω resistor. The
TEST pin may be used as the negative supply for exter-
nal CMOS gate segment drivers. LCD display annunci-
ators for decimal points, low battery indication, or
function indication may be added without adding an
additional supply. No more than 1mA should be
supplied by the TEST pin; its potential is approximately
5V below V+ (see Figure
© 2006 Microchip Technology Inc.
Manufacturer
Crystaloid
Electronics
AND
Epson
Hamlin, Inc.
Hewlett-Packard
Components
AND
Note:
Manufacturer
TYPICAL APPLICATIONS
Liquid Crystal Display Sources
Light Emitting Diode Display
Sources
Decimal Point and Annunciator
Drive
Contact LCD manufacturer for full product listing
and specifications.
5282 Hudson Dr.
Hudson, OH 44236
216-655-2429
720 Palomar Ave.
Sunnyvale, CA 94086
408-523-8200
3415 Kashikawa st.
Torrance, CA 90505
213-534-0360
612 E. Lake St.
Lake Mills, WI 53551
414-648-236100
Address/Phone
640 Page Mill Rd.
Palo Alto, CA 94304
720 Palomar Ave.
Sunnyvale, CA 94086
408-523-8200
).
Address/Phone
C5335, H5535,
T5135, SX440
FE 0201, 0701
FE 0203, 0701
FE 0501
LD-B709BZ
LD-H7992AZ
3902, 3933, 3903
Representative
Part Numbers*
LED
LED
Display
FIGURE 10-1:
Test as Logic Ground
10.4
The true differential input and differential reference
make ratiometric reading possible. Typically in a ratio-
metric operation, an unknown resistance is measured,
with respect to a known standard resistance. No
accurately defined reference voltage is needed.
The unknown resistance is put in series with a known
standard and a current passed through the pair. The
voltage developed across the unknown is applied to the
input and the voltage across the known resistor is
applied to the reference input. If the unknown equals
the standard, the display will read 1000.
The displayed reading can be determined from the
following expression:
The display will over range for:
TC7106/A/TC7107/A
TC7106A
TC7106A
Displayed Reading
TEST
V+
V+
Ratiometric Resistance
Measurements
R
TEST
UNKNOWN
BP
BP
21
37
(
Decimal
Select
Point
≥ 2 x R
Decimal Point Drive Using
)
=
STANDARD
RUnknown
-------------------------------x1000
RS
4030
4049
tan
GND
GND
V+
V+
DS21455C-page 19
dard
To LCD
Decimal
Point
To LCD
Backplane
To LCD
Decimal
Point