OPA369 Datasheet, PDF (11/19 Pages) Burr-Brown (TI) – 1.8V, 1μA max, Zerø-Crossover RAIL-TO-RAIL I/O OPERATIONAL AMPLIFIER

OPA369
OPA2369
www.ti.com ............................................................................................................................................ SBOS414B – AUGUST 2007 – REVISED DECEMBER 2008
WINDOW COMPARATOR
Figure 26 shows the OPA2369 used as a window
comparator. The threshold limits are set by V_H and
V_L, with V_H > V_L. When V_IN < V_H, the output of A1 is
low. When V_IN > V_L, the output of A2 is low.
Therefore, both op amp outputs are at 0V as long as
V_IN is between V_H and V_L. This architecture results in
no current flowing through either diode, Q1 in cutoff,
with the base voltage at 0V, and V_OUT forced high.
If V_IN falls below V_L, the output of A2 is high, current
flows through D2, and V_OUT is low. Likewise, if V_IN
rises above V_H, the output of A1 is high, current flows
through D1, and V_OUT is low. The window comparator
threshold voltages are set as follows:
R
´ V = ²
V
H _{R +R}
1
2
S
(5)
R
V= ⁴
L _{R +R}
´
V
S
3
4
(6)
V_S
R₁
R₂
V_S
V_H
A1
1/2
OPA2369
(2)
D1
R_IN(1)
2kW
V_IN
R₅
10kW
V_S
R₃
V_S
A2
1/2
V_L ^OPA2369
(2)
D2
V_S
R₇
5.1kW
V_OUT
(3)
Q1
R₆
5.1kW
R₄
NOTES: (1) R_IN protects A1 and A2 from possible excess current flow.
(2) IN4446 or equivalent diodes.
(3) 2N2222 or equivalent NPN transistor.
Figure 26. OPA2369 as a Window Comparator
Copyright © 2007–2008, Texas Instruments Incorporated
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