HEF4938B Ver la hoja de datos (PDF) - NXP Semiconductors.
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HEF4938B Datasheet PDF : 17 Pages
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NXP Semiconductors
HEF4938B
Dual precision monostable multivibrator
5.2 Pin description
Table 2. Pin description
Symbol
1CEXT, 2CEXT
1REXT/CEXT, 2REXT/CEXT
1CD, 2CD
1B, 2B
1A, 2A
1Q, 2Q
1Q, 2Q
VSS
VDD
Pin
1, 15
2, 14
3, 13
4, 12
5, 11
6, 10
7, 9
8
16
Description
external capacitor connection (always connected to ground)
external capacitor/resistor connection
direct reset input (active LOW)
input (LOW-to-HIGH triggered)
input (HIGH-to-LOW triggered)
output
complementary output (active LOW)
ground supply voltage
supply voltage
6. Functional description
Table 3.
Inputs
nA
Function table[1]
nB
L
nCD
H
Outputs
nQ
nQ
H
H
X
X
L
L
H
[1] H = HIGH voltage level; L = LOW voltage level; X = don’t care; = positive-going transition; = negative-going transition;
= one HIGH level output pulse, with the pulse width determined by CEXT and REXT;
= one LOW level output pulse, with the pulse width determined by CEXT and REXT.
CEXT
REXT
VDD
nCEXT
nREXT/CEXT
nQ
T
nA
T = REXT × CEXT
nB
nQ
nCD
001aae735
Fig 4.
The external timing resistor REXT minimum value is 5 k Its maximum permissible resistance, which holds the specified
accuracy of tW (nQ, nQ output), depends on the leakage current of the capacitor CEXT and the leakage of the HEF4938B.
The external timing capacitor CEXT minimum value is 2000 pF with no upper limit.
Connection of the external timing components REXT and CEXT
HEF4938B
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 6 — 15 November 2011
© NXP B.V. 2011. All rights reserved.
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