HA17339A Series
4. Basic Comparator
The circuit shown in figure 6 is a basic comparator. When the input voltage VIN exceeds the reference voltage VREF
,
the output goes to the high level.
VCC
3kΩ
Vin
+
HA17339A
VREF
−
Figure 6 Basic Comparator
5. Noninverting Comparator (with Hysteresis)
Assuming +VIN is 0V, when VREF is applied to the inverting input, the output will go to the low level (approximately
0V). If the voltage applied to +VIN is gradually increased, the output will go high when the value of the noninverting
input, +VIN × R2/(R1 + R2), exceeds +VREF. Next, if +VIN is gradually lowered, Vout will be inverted to the low
level once again when the value of the noninverting input, (Vout – VIN) × R1/(R1 + R2), becomes lower than VREF
.
With the circuit constants shown in figure 7, assuming VCC = 15V and +VREF = 6V, the following formula can be
derived, i.e. +VIN × 10M/(5.1M + 10M) > 6V, and Vout will invert from low to high when +VIN is > 9.06V.
R1
R1 + R2
(Vout − VIN) ×
+ VIN < 6V
(Assuming Vout = 15V)
When +VIN is lowered, the output will invert from high to low when +VIN < 1.41V. Therefore this circuit has a
hysteresis of 7.65V. Figure 8 shows the input characteristics.
VCC
VCC
3k
+VREF
+Vin
−
Vout
HA17339A
R1
+
5.1M
10M
R2
Figure 7 Noninverting Comparator
20
VCC = 15 V, +VREF = 6 V
+Vin = 0 to 10 V
16
12
8
4
0
0
5
10
15
Input Voltage VIN (V)
Figure 8 Noninverting Comparator I/O Transfer Characteristics
Rev.3.00 Mar 10, 2006 page 11 of 14
RENESAS [ RENESAS TECHNOLOGY CORP ]
