HA17901A_15 Datasheet, PDF (14/18 Pages) Renesas Technology Corp – Quadruple Comparators

HA17901A Series
5. Noninverting Comparator (with Hysteresis)
Assuming +V_IN is 0 V, when V_REF is applied to the inverting input, the output will go to the low level
(approximately 0 V). 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 = 15 V and +V_REF = 6 V, the following
formula can be derived, i.e. +V_IN × 10 M/(5.1 M + 10 M) > 6 V, and Vout will invert from low to high when +V_IN is
> 9.06 V.
(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 < 1.41 V. Therefore this circuit has a
hysteresis of 7.65 V. Figure 8 shows the input characteristics.
+V_REF
+Vin
R₁
5.1 M
V_CC
−
HA17901A
+
10 M
R₂
V_CC
3k
Vout
Figure 7 Noninverting Comparator
20
V_CC = 15 V, +V_REF = 6 V
+Vin = 0 to 10 V
16
12
8
4
0
0
5
10
15
Input Voltage V_IN (V)
Figure 8 Noninverting Comparator I/O Transfer Characteristics
Rev.1.00 Mar 10, 2006 page 12 of 15