HEF4938B View Datasheet(PDF) - Philips Electronics
Part Name
Description
MFG CO.
HEF4938B Datasheet PDF : 8 Pages
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Philips Semiconductors
Dual precision monostable multivibrator
Preliminary specification
HEF4938B
FEATURES
• Separate reset inputs
• Triggering from leading or
trailing edge
• ICC category: MSI
ORDERING AND PACKAGE INFORMATION
TYPE NUMBER
HEF4938B
PINS
16
PACKAGES
PIN POSITION MATERIAL
DIL
plastic
CODE
SOT38Z
DESCRIPTION
The HEF4938B is a dual
retriggerable-resettable monostable
multivibrator. Each multivibrator has
an active LOW trigger/retrigger input
(I0), an active HIGH trigger/retrigger
input (I1), an overriding active LOW
direct reset input (CD), an output (O)
and its complement (O), and two pins
(CTC and RCTC) for connecting the
external timing components Ct and
Rt. Typical pulse width variation over
temperature range is ±0.2%.
The HEF4938B may be triggered by
either the positive or the negative
edges of the input pulse and will
produce an accurate output pulse
with a pulse width range of 10 µs to
infinity. The duration and accuracy of
the output pulse are determined by
the external timing components
Ct and Rt. The output pulse width (T)
is equal to Rt × Ct. The linear design
techniques in LOCMOS guarantee
precise control of the output pulse
width. A LOW level at CD terminates
the output pulse immediately.
Schmitt-trigger action in the inputs
makes the circuit highly tolerant for
slower rise and fall times.
PIN DESCRIPTION
PIN NO.
1, 15
2, 14
3, 13
4, 12
5, 11
6, 10
7, 9
8
16
SYMBOL
CTC A, CTC B
RCTC A, RCTC B
CDA, CDB
I1A, I1B
I0A, I0B
OA, OB
OA, OB
VSS
VDD
NAME AND FUNCTION
external capacitor connections
external capacitor/resistor connections
direct reset input (active LOW)
input (LOW-to-HIGH triggered)
input (HIGH-to-LOW triggered)
output
complementary output (active LOW)
ground (0 V)
positive supply voltage
FUNCTION TABLE
INPUTS
OUTPUTS
I0
I1 CD
O
O
↑LH
H↑ H
XX L
L
H
Notes
1. H = HIGH voltage level
2. L = LOW voltage level
Fig.1 Pin configuration.
3. X = state is immaterial
4. ↑ = positive-going transition
5. ↓ = negative-going transition
6.
= positive output pulse
7.
= negative output pulse
Fig.2 Functional diagram.
January 1995
2
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