TC820 TelCom Semiconductor, TC820 Datasheet - Page 12

• Manufacturer Part Number: TC820
• Description: 3-3/4 DIGIT A/D CONVERTER WITH FREQUENCY COUNTER AND LOGIC PROBE
• Manufacturer: TelCom Semiconductor

TC820
3-160
PROBE
LOGIC
INPUT
Figure 5. TC820 Auto-Range Decimal Point Selection
40kHz – 399.9kHz
4kHz – 39.99kHz
0Hz – 3999Hz
400kHz
f IN
vs Frequency Counter Input
DP3
EXTERNAL
LOGIC LEVEL
DETECTION
AND PULSE
STRETCHING
DP2
DECIMAL POINT
DP1
CMOS
LOGIC
LEVELS
NONE
DP3
DP2
DP1
Figure 6. Logic Probe Simplified Schematic
V
DD
DP0/LO
DP1/HI
LOGIC
86dB common-mode rejection ratio minimizes error. Com-
mon-mode voltages do, however, affect the integrator out-
put level. A worst-case condition exists if a large, positive
V
tial signal. The negative signal drives the integrator output
positive along with V
integrator output swing can be reduced below the recom-
mended 2V full-scale swing. The integrator output will swing
within 0.3V of V
Reference (V
true differential inputs. In addition, the reference voltage can
be generated anywhere within the power supply voltage of
the converter. The differential reference inputs permit
ratiometric measurements and simplify interfacing with sen-
sors, such as load cells and temperature sensors.
CM
In systems where common-mode voltages exist, the
The TC820 reference, like the analog signal input, has
exists in conjunction with a full-scale, negative differen-
DD
DRIVERS
3-3/4 A/D CONVERTER WITH
DD
, V
LCD
NC
or V
SS
CM
HIGH
LOW
)
TELCOM SEMICONDUCTOR, INC.
FREQUENCY COUNTER
(Figure 9). For such applications, the
DD
without increased linearity error.
AND LOGIC PROBE
DISABLE A/D CONVERTER
LCD
TO
BUZZER
TC820