MIC841NYMT(2015) 查看數據表（PDF） - Micrel
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MIC841NYMT Datasheet PDF : 11 Pages
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Micrel, Inc.
Using 3.1V for the VIN(LO) threshold allows calculation of
the two remaining resistor values:
VIN(LO)
=
3.1V
=
1.24V
R2
1MΩ
+ 344kΩ
Eq. 4
MIC841/842
Where:
R2 = 56kΩ
R1 = 1MΩ − R2 − R3
R1 = 600kΩ
The accuracy of the resistors can be chosen based upon
the accuracy required by the system.
VIN
VIN(HI)
VIN(LO)
0V
VHYSTERISIS
OUT
H AND N VERSIONS 0V
OUT
L VERSION
0V
Figure 2. Output Response and Hysteresis
Programming the MIC842 Thresholds
The voltage threshold is calculated using Equation 5:
Figure 3. MIC842 Example Circuit
In order to provide the additional criteria needed to solve
for the resistor values, the resistors can be selected such
that they have a given total value, that is, R1 + R2 =
RTOTAL. A value such as 1MΩ for RTOTAL is a reasonable
value because it draws minimum current but has no
significant effect on accuracy.
Input Transients
The MIC841/2 is inherently immune to very short
negative-going “glitches.” Very brief transients may
exceed the VIN(LO) threshold without tripping the output.
As shown in Figure 4, the narrower the transient, the
deeper the threshold overdrive that will be ignored by the
MIC841/2. The graph represents the typical allowable
transient duration for a given amount of threshold
overdrive that will not generate an output.
VIN(LO)
=
VREF
R1+ R2
R2
Eq. 5
Where:
VREF = 1.240V
Figure 4. Input Transient Response
July 24, 2015
7
Revision 5.0
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