LTC1843 Просмотр технического описания (PDF) - Linear Technology
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LTC1843 Datasheet PDF : 12 Pages
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LTC1841/LTC1842/LTC1843
APPLICATIONS INFORMATION
5V
TO
8V
R2
10k
3 IN A+
7
V+
+
–
5 HYST
6 REF
LTC1843
5V
1M
OUT A 1
OUT A
IREF
R1
R2
6 REF
LTC1843
5
HYST
V–
2
R1 = VHB
(2)(IREF)
( ) 1.182V – VHB
R2 =
2
IREF
1841/43 F04
Figure 4. Programmable Hysteresis
R3
R1
2.4M
430Ω
V–
C1
2
1µF
1841/43 F03a
Figure 3a. Power Supply Transient Test Circuit
15%. If hysteresis is not wanted, the HYST pin should be
shorted to REF. Acceptable values for IREF range are from
0.1µA to 5µA. If 2.4M is chosen for R2, then the value of
R1 is equal to the value of VHB.
Window Detector
The LTC1843 is ideal for use as a micropower window
8V
detector as shown in Figure 5. The values of R1, R2 and R3
V+
5V
are selected for a 4.5V undervoltage threshold and a 5.5V
overvoltage threshold. R4 and R5 set the hysteresis volt-
VREF
age. The following design procedure can be used to select
the component values:
OUT
2ms/DIV
1841/1843 F03b
Figure 3b. Power Supply Transient Rejection
Hysteresis
Hysteresis can be added to the LTC1842/LTC1843 by
connecting a resistor (R1) between the REF and HYST pins
and a second resistor (R2) from HYST to V – (Figure 4).
The difference between the upper and lower threshold
voltages, or hysteresis voltage band (VHB), is equal to twice
the voltage difference between the REF and HYST pins.
As more hysteresis is added, the upper threshold in-
creases the same amount as the low threshold decreases.
The maximum voltage allowed between REF and HYST
pins is 50mV, producing a maximum hysteresis voltage
band of 100mV. The hysteresis band may vary by up to
VIN
R3
1M
R2
62.2k
R1
294k
5V
7
V + LTC1843
1M
3 IN A+
+
OUT A 1
–
5 HYST
6 REF
R5
+
10k
4 IN B–
–
R4
2.4M
V–
2
OUT B 8
VOTH = 5.5V
VUTH = 4.5V
1841/43 F05
Figure 5. Dual Level Detector
8
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