HCC4047BF STMICROELECTRONICS [STMicroelectronics], HCC4047BF Datasheet - Page 7

• Manufacturer Part Number: HCC4047BF
• Description: LOW-POWELOW-POWER MONOSTABLE/ASTABLE MULTIVIBRATOR
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Typical Output High (source) Current Charac-
teristics.
APPLICATION INFORMATION
1 - CIRCUIT DESCRIPTION
Astable operation is enabled by a high level on the
ASTABLE input. The period of the square wave at
the Q and Q Outputs in this mode of operation is a
function of the external components employed.
”True” input pulses on the ASTABLE input or ”Com-
plement” pulses on the ASTABLE input allow the cir-
cuit to be used as a gatable multivibrator. The
OSCILLATOR output period will be half of the Q ter-
minal output in the astable mode. However, a 50%
duty cycle is not guaranteed at this output. In the
monostable mode, positive-edge triggering is ac-
complished by application of a leading-edge pulse
to the +TRIGGER input and a low level to the –TRI-
GGER input. For negative-edge triggering, a trail-
ing-edge pulse is applied to the –TRIGGER and a
high level is applied to the +TRIGGER. Input pulses
may be of any duration relative to the output pulse.
The multivibrator can be retriggered (on the leading
edge only) by applying a common pulse to both the
RETRIGGER and +TRIGGER inputs. In this mode
Minimum Output High (source) Current Charac-
teristics.
the output pulse remains high as long as the input
pulse period is shorter than the period determined
by the RC components. An external countdown op-
tion can be implemented by coupling ”Q” to an ex-
ternal ”N” counter and resetting the counter with the
trigger pulse. The counter output pulse is fed back
to the ASTABLE input and has a duration equal to
N times the period of the multivibrator. A high level
on the EXTERNAL RESET input assures no output
pulse during an ”ON” power condition. This input
can also be activated to terminate the output pulse
at any time. In the monostable mode, a high-level or
power-on reset pulse, must be applied to the EX-
TERNAL RESET whenever V
2 - ASTABLE MODE
The following analysis presents worst-case vari-
ations from unit-to-unit as a function of transfer-volt-
age (V
(astable) operation.
TR
) shift (33% – 67% V
HCC/HCF4047B
DD
DD
is applied.
) for free-running
7/15