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MM74HC4538SJ

P1-P3P4-P6P7-P9P10-P10
www.fairchildsemi.com 4
MM74HC4538
Circuit Operation (Continued)
toggle, taking the Q output of the HC4538 to a LOW State
(#19), and completing the time-out cycle.
RESET OPERATION
A low voltage applied to the Reset pin always forces the Q
output of the HC4538 to a LOW State.
The timing diagram illustrates the case in which reset
occurs (#20) while C
X
is charging up toward the reference
voltage of the upper reference circuit (#21). When a reset
occurs, the output of the reset latch goes LOW (#22), turn-
ing ON transistor M1. Thus C
X
is allowed to quickly charge
up to V
CC
(#23) to await the next trigger signal.
Recovery time is the required delay after reset goes inac-
tive to a new trigger rising edge. On the diagram it is shown
as (#26) to (#27).
RETRIGGER OPERATION
In the retriggerable mode, the HC4538 may be retriggered
during timing out of the output pulse at any time after the
trigger-control circuit flip-flop has been reset (#24).
Because the trigger-control circuit flip-flop resets shortly
after C
X
has discharged to the reference voltage of the
lower reference circuit (#25), the minimum retrigger time, t
rr
is a function of internal propagation delays and the dis-
charge time of C
X
:
at room temperature
POWER-DOWN CONSIDERATIONS
Large values of C
X
may cause problems when powering
down the MM74HC4538 because of the amount of energy
stored in the capacitor. When a system containing this
device is powered down, the capacitor may discharge from
V
CC
through the input protection diodes at pin 2 or pin 14.
Current through the protection diodes must be limited to 30
mA; therefore, the turn-off time of the V
CC
power supply
must not be faster than t
= V
CC
•C
X
/(30 mA). For example, if
V
CC
= 5V and C
X
= 15 µF, the V
CC
supply must turn OFF
no faster than t
= (15V)•(15 µF)/30 mA = 2.5 ms. This is
usually not a problem because power supplies are heavily
filtered and cannot discharge at this rate.
When a more rapid decrease of V
CC
to zero volts occurs,
the MM74HC4538 may sustain damage. To avoid this pos-
sibility, use an external clamping diode, D
X
, connected
from V
CC
to the C
X
pin.
SET UP RECOMMENDATIONS
Minimum R
X
= 1 kΩ
Minimum C
X
= 0 pF.
5 www.fairchildsemi.com
MM74HC4538
Absolute Maximum Ratings(Note 1)
(Note 2)
Recommended Operating
Conditions
Note 1: Maximum Ratings are those values beyond which damage to the
device may occur.
Note 2: Unless otherwise specified all voltages are referenced to ground.
Note 3: Power Dissipation Temperature Derating: Plastic “N” Package: −
12mW/°C from 65°C to 85°C.
DC Electrical Characteristics (Note 4)
Note 4: For a power supply of 5V ±10% the worst case output voltages (V
OH
, and V
OL
) occur for HC at 4.5V. Thus the 4.5V values should be used when
designing with this supply. Worst case V
IH
and V
IL
occur at V
CC
= 5.5V and 4.5V respectively. (The V
IH
value at 5.5V is 3.85V.) The worst case leakage cur-
rent (I
IN
, I
CC
, and I
OZ
) occur for CMOS at the higher voltage and so the 6.0V values should be used.
Supply Voltage (V
CC
) −0.5 to +7.0V
DC Input Voltage (V
IN
) −1.5 to V
CC
+1.5V
DC Output Voltage (V
OUT
) −0.5 to V
CC +
0.5V
Clamp Diode Current (I
IK
, I
OK
) ±20 mA
DC Output Current, per pin (I
OUT
) ±25 mA
DC V
CC
or GND Current, per pin (I
CC
) ±50 mA
Storage Temperature Range (T
STG
) −65°C to +150°C
Power Dissipation (P
D
)
(Note 3) 600 mW
S.O. Package only 500 mW
Lead Temperature (T
L
)
(Soldering 10 seconds) 260
°C
Min Max Units
Supply Voltage (V
CC
)26V
DC Input or Output Voltage 0 V
CC
V
(V
IN
, V
OUT
)
Operating Temperature Range (T
A
) −40 +85 °C
Input Rise or Fall Times
(Reset only)
(t
r
, t
f
) V
CC
= 2.0V 1000 ns
V
CC
= 4.5V 500 ns
V
CC
= 6.0V 400 ns
Symbol Parameter Conditions
V
CC
T
A
= 25°CT
A
= −40 to 85°CT
A
= −55 to 125°C
Units
Typ Guaranteed Limits
V
IH
Minimum HIGH Level Input 2.0V 1.5 1.5 1.5 V
Voltage 4.5V 3.15 3.15 3.15 V
6.0V 4.2 4.2 4.2 V
V
IL
Maximum LOW Level Input 2.0V 0.5 0.5 0.5 V
Voltage 4.5V 1.35 1.35 1.35 V
6.0V 1.8 1.8 1.8 V
V
OH
Minimum HIGH Level Output V
IN
= V
IH
or V
IL
Voltage |I
OUT
| ≤ 20 µA 2.0V 2.0 1.9 1.9 1.9 V
4.5V 4.5 4.4 4.4 4.4 V
6.0V 6.0 5.9 5.9 5.9 V
V
IN
= V
IH
or V
IL
|I
OUT
| ≤ 4.0 mA 4.5V 3.98 3.84 3.7 V
|I
OUT
| ≤ 5.2 mA 6.0V 5.48 5.34 5.2 V
V
OL
Maximum LOW Level Output V
IN
= V
IH
or V
IL
2.0V 0 0.1 0.1 0.1 V
Voltage |I
OUT
| ≤ 20 µA 4.5V 0 0.1 0.1 0.1 V
6.0V 0 0.1 0.1 0.1 V
V
IN
= V
IH
or V
IL
|I
OUT
| ≤ 4.0 mA 4.5V 0.26 0.33 0.4 V
|I
OUT
| ≤ 5.2 mA 6.0V 0.26 0.33 0.4 V
I
IN
Maximum Input Current V
IN
= V
CC
or GND 6.0V ±0.1 ±1.0 ±1.0 µA
(Pins 2, 14) (Note 5)
I
IN
Maximum Input Current V
IN
= V
CC
or GND 6.0V ±0.1 ±1.0 ±1.0 µA
(all other pins)
I
CC
Maximum Active Supply Pins 2, 14 = 0.5 V
CC
Active Current Q1, Q2 = HIGH 6.0V 150 250 400 µA
V
IN
= V
CC
or GND
I
CC
Maximum Quiescent Supply Pins 2, 14 = OPEN
Quiescent Current Q1, Q2 = LOW 6.0V 130 220 350 µA
V
IN
= V
CC
or GND
www.fairchildsemi.com 6
MM74HC4538
DC Electrical Characteristics (Continued)
Note 5: The device must be set up with 3 steps before measuring I
IN
:
AC Electrical Characteristics
V
CC
= 5V, T
A
= 25° C, C
L
= 15 pF, t
r
= t
f
= 6 ns
AC Electrical Characteristics
C
L
= 50 pF, t
r
= t
f
= 6 ns (unless otherwise specified)
Clear A B
1. H L H
2. H H H
3. H L H
Symbol Parameter Conditions Typ Limit Units
t
PLH
Maximum Propagation Delay A, or B to Q 23 45 ns
t
PHL
Maximum Propagation Delay A, or B to Q 26 50 ns
t
PHL
Maximum Propagation Delay Clear to Q 23 45 ns
t
PLH
Maximum Propagation Delay Clear to Q 26 50 ns
t
W
Minimum Pulse Width A, B or Clear 10 16 ns
Symbol Parameter Conditions
V
CC
T
A
=25°CT
A
=−40 to 85°CT
A
= −55 to 125°C
Units
Typ Guaranteed Limits
t
PLH
Maximum Propagation 2.0V 100 250 315 373 ns
Delay A, or B to Q 4.5V 25 50 63 75 ns
6.0V 21 43 54 63 ns
t
PHL
Maximum Propagation 2.0V 110 275 347 410 ns
Delay A, or B to Q 4.5V 28 55 69 82 ns
6.0V 23 47 59 70 ns
t
PHL
Maximum Propagation 2.0V 100 250 315 373 ns
Delay Clear to Q 4.5V 25 50 63 75 ns
6.0V 21 43 54 63 ns
t
PLH
Maximum Propagation 2.0V 110 275 347 410 ns
Delay Clear to Q 4.5V 28 55 69 82 ns
6.0V 23 47 59 70 ns
t
TLH
, t
THL
Maximum Output 2.0V 30 75 95 110 ns
Rise and Fall 4.5V 10 15 19 22 ns
Time 6.0V 8 13 16 19 ns
t
r
, t
f
Maximum Input 2.0V 1000 1000 1000 ns
Rise and Fall 4.5V 500 500 500 ns
Time (Reset only) 6.0V 400 400 400 ns
t
W
Minimum Pulse Width 2.0V 80 101 119 ns
A, B, Clear 4.5V 16 20 24 ns
6.0V 14 17 20 ns
t
REC
Minimum Recovery 2.0V −50 0 0 ns
Time, Clear 4.5V 0 0 0 ns
Inactive to A or B 6.0V 0 0 0 ns
t
WQ
Output Pulse Width C
X
= 12 pF Min 3.0V 283 190 ns
R
X
= 1 kΩ 5.0V 147 120 ns
Max 3.0V 283 400 ns
5.0V 147 185 ns
t
WQ
Output Pulse Width C
X
= 100 pF Min 3.0V 1.2 µs
R
X
= 10 kΩ 5.0V 1.0 µs
Max 3.0V 1.2 µs
5.0V 1.0 µs
P1-P3P4-P6P7-P9P10-P10

MM74HC4538SJ

Mfr. #:
Buy MM74HC4538SJ
Manufacturer:
ON Semiconductor / Fairchild
Description:
Monostable Multivibrator Dual Multivibrator
Lifecycle:
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