HA17901 Datasheet, PDF (12/16 Pages) Hitachi Semiconductor – Quadruple Comparators

HA17901, HA17339 Series
V_CC
V_CC
500p
100k
–
A₁
3k
5.1k
+V_C
10 _HA17901
0.1µ
+
0.01µ
Frequency
control
20k
20k
V_CC/2
voltage
input
50k
V_CC
A₃
–
V_CC/2
V_CC = 30V
+250mV < +V_C < +50V
700Hz < / < 100kHz
HA17901
+
100k
V_CC
+
A₂
HA17901
–
Figure 5 Voltage Controlled Oscillator
V_CC
3k
Output 1
Output 2
4. Basic Comparator
The circuit shown in figure 6 is a basic comparator. When the input voltage V_IN exceeds the reference
voltage V_REF, the output goes to the high level.
V_CC
Vin
+
3kΩ
V_REF
–
Figure 6 Basic Comparator
5. Noninverting Comparator (with Hysteresis)
Assuming +V_IN is 0V, when V_REF is applied to the inverting input, the output will go to the low level
(approximately 0V). If the voltage applied to +V_IN is gradually increased, the output will go high when
the value of the noninverting input, +V_IN × R₂/(R₁ + R₂), exceeds +V_REF. Next, if +V_IN is gradually
lowered, Vout will be inverted to the low level once again when the value of the noninverting input,
(Vout – V_IN) × R₁/(R₁ + R₂), becomes lower than V_REF. With the circuit constants shown in figure 7,
assuming V_CC = 15V and +V_REF = 6V, the following formula can be derived, i.e. +V_IN × 10M/(5.1M +
10M) > 6V, and Vout will invert from low to high when +V_IN is > 9.06V.
(Vout
–
V_IN)
×
R₁
R₁ + R₂
+
V_IN
<
6V
(Assuming Vout = 15V)
When +V_IN is lowered, the output will invert from high to low when +V_IN < 1.41V. Therefore this
circuit has a hysteresis of 7.65V. Figure 8 shows the input characteristics.
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