Device Operating
Temperature Range Package
SEMICONDUCTOR
TECHNICAL DATA
DUAL TIMING CIRCUIT
ORDERING INFORMATION
MC3456P
NE556D 0° to +70°CPlastic DIP
SO–14
PIN CONNECTIONS
Order this document by MC3456/D
P SUFFIX
PLASTIC PACKAGE
CASE 646
D SUFFIX
PLASTIC PACKAGE
CASE 751
(SO–14)
(Top View)
Discharge A
Threshold A
Control A
Reset A
Output A
T rigger A
Gnd
VCC
Discharge B
Threshold B
Control B
Reset B
Output B
T rigger B
1
2
3
4
5
6
78
9
10
11
12
13
14
1
MOTOROLA ANALOG IC DEVICE DATA
The MC3456 dual timing circuit is a highly stable controller capable of
producing accurate time delays, or oscillation. Additional terminals are
provided for triggering or resetting if desired. In the time delay mode of
operation, the time is precisely controlled by one external resistor and
capacitor per timer. For astable operation as an oscillator, the free running
frequency and the duty cycle are both accurately controlled with two external
resistors and one capacitor per timer . The circuit may be triggered and reset
on falling waveforms, and the output structure can source or sink up to
200 mA or drive MTTL circuits.
•Direct Replacement for NE556/SE556 Timers
•Timing from Microseconds through Hours
•Operates in Both Astable and Monostable Modes
•Adjustable Duty Cycle
•High Current Output can Source or Sink 200 mA
•Output can Drive MTTL
•Temperature Stability of 0.005% per °C
•Normally “On” or Normally “Off” Output
•Dual Version of the Popular MC1455 T imer
Figure 1. 22 Second Solid State Time Delay Relay Circuit
Figure 2. Block Diagram (1/2 Shown)
Figure 3. General Test Circuit
Test circuit for measuring DC parameters (to set output and measure parameters):
a) When VS
w
2/3 VCC, VO is low.
b) When VS
v
1/3 VCC, VO is high.
c) When VO is low, Pin 7 sinks current. To test for Reset, set VO high,
c) apply Reset voltage, and test for current flowing into Pin 7. When Reset
c) is not in use, it should be tied to VCC.
1.0 k Load
MT2
10 k
0.1
µ
F 0.01
µ
F1
52
4386
7
1.0
µ
FC
20 M GMT1
–10 V 1N4003
117 Vac/60 Hz
1N4740 3.5 k
250 V –
+
t = 1.1; R and C = 22 sec
Time delay (t) is variable by
changing R and C (see Figure 16). 10
µ
F
VCC
Threshold
Control Voltage
Trigger
2 (12)
3 (11)
6 (8)
5 k
14
5 k
5 k
+
–
Comp
A
+
–
Comp
B
7
Gnd Reset
4 (10)
R
S
Flip
Flop Q
Inhibit/
Reset
1 (13)
5 (9)
Discharge
Output
R
1/2
MC3456
VR
Reset 4 8
ICC VCC
700
Discharge
6
Threshold
7
Ith 2.0 k VS
Trigger
2
Gnd
1
3
ISink
ISource
VO
0.01
µ
F+5
Control
Voltage
Output
VCC
1/2
MC3456
Motorola, Inc. 1996 Rev 2
MC3456
2MOTOROLA ANALOG IC DEVICE DATA
MAXIMUM RATINGS (TA = +25°C, unless otherwise noted.)
Rating Symbol Value Unit
Power Supply Voltage VCC +18 Vdc
Discharge Current Idis 200 mA
Power Dissipation (Package Limitation)
P Suffix, Plastic Package, Case 646
Derate above TA = +25°C
D Suffix, Plastic Package, Case 751
Derate above TA = +25°C
PD625
5.0
1.0
8.0
mW
mW/°C
W
mW/°C
Operating Ambient Temperature Range TA0 to +70 °C
Storage Temperature Range Tstg –65 to +150 °C
ELECTRICAL CHARACTERISTICS (TA = +25°C, VCC = +15 V, unless otherwise noted.)
Characteristics Symbol Min Typ Max Unit
Supply Voltage VCC 4.5 – 16 V
Supply Current
VCC = 5.0 V, RL = ∞
VCC = 15 V, RL = ∞Low State, (Note 1)
ICC –
–6.0
20 12
30
mA
T iming Error (Note 2)
Monostable Mode (RA = 2.0 kΩ; C = 0.1 µF)
Initial Accuracy
Drift with Temperature
Drift with Supply Voltage
Astable Mode (RA = RB = 2.0 kΩ to 100 kΩ; C = 0.01 µF)
Initial Accuracy
Drift with Temperature
Drift with Supply Voltage
–
–
–
–
–
–
0.75
50
0.1
2.25
150
0.3
–
–
–
–
–
–
%
PPM/°C
%/V
%
PPM/°C
%/V
Threshold V oltage Vth –2/3 – xVCC
T rigger Voltage
VCC = 15 V
VCC = 5.0 V
VT–
–5.0
1.67 –
–
V
T rigger Current IT– 0.5 – µA
Reset Voltage VR0.4 0.7 1.0 V
Reset Current IR– 0.1 – mA
Threshold Current (Note 3) Ith –0.03 0.1 µA
Control V oltage Level
VCC = 15 V
VCC = 5.0 V
VCL 9.0
2.6 10
3.33 11
4.0
V
Output V oltage Low
(VCC = 15 V)
ISink = 10 mA
ISink = 50 mA
ISink = 100 mA
ISink = 200 mA
(VCC = 5.0 V)
ISink = 5.0 mA
VOL
–
–
–
–
–
0.1
0.4
2.0
2.5
0.25
0.25
0.75
2.75
–
0.35
V
Output V oltage High
(ISource = 200 mA)
VCC = 15 V
(ISource = 100 mA)
VCC = 15 V
VCC = 5.0 V
VOH
–
12.75
2.75
12.5
13.3
3.3
–
–
–
V
Toggle Rate RA = 3.3 kΩ, RB = 6.8 kΩ, C = 0.003 µF (Figure 17, 19) – – 100 – kHz
Discharge Leakage Current Idis –20 100 nA
Rise Time of Output tOLH –100 – ns
Fall T ime of Output tOHL –100 – ns
Matching Characteristics Between Sections
Monostable Mode
Initial T iming Accuracy
T iming Drift with Temperature
Drift with Supply Voltage
–
–
–
1.0
±10
0.2
2.0
–
0.5
%
ppm/°C
%/V
NOTES: 1.Supply current is typically 1.0 mA less for each output which is high.
2.Tested at VCC = 5.0 V and VCC = 15 V.
3.This will determine the maximum value of RA + RB for 15 V operation. The maximum total R = 20 mΩ.
MC3456
3
MOTOROLA ANALOG IC DEVICE DATA
25
°
C
ISink (mA)
ISink (mA)
VCC, SUPPLY VOLTAGE (Vdc)
ISink (mA)
ISource (mA)
Figure 4. Trigger Pulse Width
VT (min), MINIMUM TRIGGER VOLTAGE (X VCC = Vdc)
Figure 5. Supply Current
Figure 6. High Output Voltage Figure 7. Low Output Voltage
(@ VCC = 5.0 Vdc)
Figure 8. Low Output Voltage
(@ VCC = 10 Vdc) Figure 9. Low Output Voltage
(@ VCC = 15 Vdc)
0.4
150
125
100
75
50
25
0
PW, PULSE WIDTH (ns MIN)
ICC, SUPPLY CURRENT (mA)
1.0
1.0
VCC–VOH (Vdc)
VOL, (Vdc)
0.30.20.10
70
°
C
25
°
C
10
8.0
6.0
4.0
2.0
0155.0 10
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
02.0 5.0 10 20 50 100
25
°
C
5.0 V
≤
VCC
≤
15 V
10
1.0
0.1
0.011.0 2.0 5.0 10 20 50 100
2.0 5.0 10 20 50 100
10
1.0
0.1
0.01 1.0 2.0 5.0 10 20 50 100
10
1.0
0.1
0.01
25
°
C
0
°
C
25
°
C
VOL, (Vdc)
VOL, (Vdc)
25
°
C
MC3456
4MOTOROLA ANALOG IC DEVICE DATA
TA, AMBIENT TEMPERATURE (
°
C)
Figure 10. Delay Time versus Supply Voltage
VCC, SUPPLY VOLTAGE (Vdc)
Figure 11. Delay Time versus Temperature
Figure 12. Propagation Delay
versus Trigger Voltage
5.0
0VT
(
min
)
, MINIMUM TRIGGER VOLTAGE (x VCC = Vdc)
td, DELAY TIME NORMALIZED
td, DELAY TIME NORMALIZED
, PROPAGATION DELAY TIME (ns)tpd
1.015
1.010
1.005
1.000
0.995
0.990
0.985 0101510 20
1.015
1.010
1.005
1.000
0.995
0.990
0.985
–75 –50 –25 0 25 50 75 100 125
300
250
200
150
100
50
00.1 0.2 0.3 0.4
0
°
C
70
°
C25
°
C
MC3456
5
MOTOROLA ANALOG IC DEVICE DATA
Figure 13. 1/2 Representative Circuit Schematic
100
Threshold
Comparator Trigger
Comparator Flip–Flop Output
VCC
Threshold
Trigger
Reset
Discharge
Gnd
Discharge
Reset
100 k 5.0 k
5.0 k e
c b
7.0 k
6.8 k
3.9 k
cb
220
4.7 k
Output
Control Voltage
1.0 k4.7 k 830 4.7 k
10 k
4.7 k
5.0 k
GENERAL OPERATION
The MC3456 is a dual timing circuit which uses as its
timing elements an external resistor/capacitor network. It can
be used in both the monostable (one shot) and astable
modes with frequency and duty cycle, controlled by the
capacitor and resistor values. While the timing is dependent
upon the external passive components, the monolithic circuit
provides the starting circuit, voltage comparison and other
functions needed for a complete timing circuit. Internal to the
integrated circuit are two comparators, one for the input
signal and the other for capacitor voltage; also a flip–flop and
digital output are included. The comparator reference
voltages are always a fixed ratio of the supply voltage thus
providing output timing independent of supply voltage.
Monostable Mode
In the monostable mode, a capacitor and a single resistor
are used for the timing network. Both the threshold terminal
and the discharge transistor terminal are connected together
in this mode (refer to circuit Figure 15). When the input
voltage to the trigger comparator falls below 1/3 VCC the
comparator output triggers the flip–flop so that it’s output sets
low. This turns the capacitor discharge transistor “off” and
drives the digital output to the high state. This condition
allows the capacitor to charge at an exponential rate which is
set by the RC time constant. When the capacitor voltage
reaches 2/3 VCC the threshold comparator resets the
flip–flop. This action discharges the timing capacitor and
returns the digital output to the low state. Once the flip–flop
has been triggered by an input signal, it cannot be retriggered
until the present timing period has been completed. The time
that the output is high is given by the equation t = 1.1 RA C.
Various combinations of R and C and their associated times
are shown in Figure 14. The trigger pulse width must be less
than the timing period.
A reset pin is provided to discharge the capacitor thus
interrupting the timing cycle. As long as the reset pin is low,
the capacitor discharge transistor is turned “on” and prevents
the capacitor from charging. While the reset voltage is
applied the digital output will remain the same. The reset pin
should be tied to the supply voltage when not in use.
Figure 14. Time Delay
C, CAPACITANCE ( F)
µ
100
10
1.0
0.1
0.01
0.001
10
µ
s 100
µ
s 1.0 ms 10 ms 100 ms 1.0 10 100
td, TIME DELAY (s)
MC3456
6MOTOROLA ANALOG IC DEVICE DATA
Figure 15. Monostable Circuit Figure 16. Monostable Waveforms
Figure 17. Astable Circuit
(RA = 10 k
Ω
, C = 0.01
µ
F, RL = 1.0 k
Ω
, VCC = 15 V)
t = 20
µ
s/cm
(RA = 5.1 k
Ω
, C = 0.0 1
µ
F, RL = 1.0 k
Ω
, RB = 3.9 k
Ω
, VCC = 15 V)
t = 50
µ
s/cm
Figure 18. Astable Waveforms
Control
Voltage
3 (11)
RL
+VCC (5.0 to 15 V)
Reset VCC
14
Discharge
1 (13)
2 (12) Threshold
0.01
µ
F
7
6 (8)
Trigger
Output
5 (9)
4 (10)
RA
RL
C
Gnd
1/2
MC3456 RB
RL
+VCC (5.0 V to 15 V)
Reset VCC
14 Discharge
1 (13)
2 (12)
Threshold
Control
Voltage0.01
µ
F
7
6 (8)
Trigger
Output
5 (9)
4 (10)
RA
RL
C
3 (11)
Gnd
1/2
MC3456
Pin numbers in parenthesis ( ) indicate B–Channel
Astable Mode
In the astable mode the timer is connected so that it will
retrigger itself and cause the capacitor voltage to oscillate
between 1/3 VCC and 2/3 VCC (see Figure 17).
The external capacitor charges to 2/3 VCC through RA and
RB and discharges to 1/3 VCC through RB. By varying the
ratio of these resistors the duty cycle can be varied. The
charge and discharge times are independent of the supply
voltage.
The charge time (output high) is given by:
t1 = 0.695 (RA+RB) C
The discharge time (output low) by:
t2 = 0.695 (RB) C
Thus the total period is given by:
T = t1 + t2 = 0.695 (RA + 2RB) C
The frequency of oscillation is then: f = 1
T=(RA +2RB) C
1.44
and may be easily found as shown in Figure 19.
RA +2RB
RB
The duty cycle is given by: DC =
To obtain the maximum duty cycle, RA must be as small as
possible; but it must also be large enough to limit the
discharge current (Pin 7 current) within the maximum rating
of the discharge transistor (200 mA).
The minimum value of RA is given by:
RA≥VCC (Vdc)
I7 (A) ≥VCC (Vdc)
0.2
Figure 19. Free Running Frequency
C, CAPACITANCE ( F)
µ
100
10
1.0
0.1
0.01
0.001 (RA + 2 RB)
0.1 1.0 10 100 1.0 k 10 k 100 k
f, FREE RUNNING FREQUENCY (Hz)
MC3456
7
MOTOROLA ANALOG IC DEVICE DATA
APPLICATIONS INFORMATION
Tone Burst Generator
For a tone burst generator, the first timer is used as a
monostable and determines the tone duration when triggered
by a positive pulse at Pin 6. The second timer is enabled by
the high output of the monostable. It is connected as an
astable and determines the frequency of the tone.
Dual Astable Multivibrator
This dual astable multivibrator provides versatility not
available with single timer circuits. The duty cycle can be
adjusted from 5% to 95%. The two outputs provide two phase
clock signals often required in digital systems. It can also be
inhibited by use of either reset terminal.
(RA + 2RB) C
Figure 20. Tone Burst Generator
Figure 21. Dual Astable Multivibrator
RT
Trigger Trigger
Trigger
Reset
4
Discharge
Threshold
7 Gnd
1/2
MC3456
14 VCC
5
Output
10
Reset
39
Control
0.01
µ
F
Output
7 Gnd 0.01 mF C2
14 VCC 13 Discharge
12 Threshold
8
11 Control
RB
RA
+ 15 V
Gnd
C1–
R1
C1
Reset
2
Discharge
1
414 10 k
5
1N914 1N914 10 k
9
Output
Trigger
10 Reset
+15 V
R2
Threshold
12
13
Discharge
C2
Gnd
11 Control
Voltage
0.001 8
Output
0.001
Output
6
37
Gnd
f = 0.91
(R1 + R2) C for C1 = C2 Duty Cycle R2
R1 + R2
t = 1.1 RT C1 f = 1.44
Control
Voltage
Threshold
Trigger
1/2
MC3456
1/2
MC3456
1/2
MC3456
6
1
2
MC3456
8MOTOROLA ANALOG IC DEVICE DATA
Pulse Width Modulation
If the timer is triggered with a continuous pulse train in the
monostable mode of operation, the charge time of the
capacitor can be varied by changing the control voltage at
Pin 3. In this manner, the output pulse width can be
modulated by applying a modulating signal that controls the
threshold voltage.
Test Sequences
Several timers can be connected to drive each other for
sequential timing. An example is shown in Figure 24 where
the sequence is started by triggering the first timer which runs
for 10 ms. The output then switches low momentarily and
starts the second timer which runs for 50 ms and so forth.
Figure 22. Pulse Width Modulation Waveforms Figure 23. Pulse Width Modulation Circuit
t = 0.5 ms/cm
(RA = 10 kW, C = 0.02 mF, VCC = 15 V)
+VCC (5.0 V to 15 V)
RL4 (10)
Reset VCC 14
RA
Discharge
1 (13)
Threshold
2 (12)
Control
3 (11)
C
Modulation
Input
Output
5 (9)
Trigger
6 (8)
Output
Clock
Input Gnd 7
1/2
MC3456
Modulation Input Voltage 5.0 V/cm
Clock Input Voltage
5.0 V/cm
Output Voltage
5.0 V/cm
Capacitor V oltage
5.0 V/cm
Figure 24. Sequential Timing Circuit
9.1 k
Threshold
VCC Reset 27 k 9.1 k
VCC Reset
27 k 50 k
VCC Reset
Control
Output
Load
GndGnd
Load
5.0
µ
F
0.001
µ
F
GndTrigger
Discharge
1.0
µ
F
Control
Output
0.01
µ
F
0.001
µ
F
Threshold
Threshold
Discharge
Trigger
5.0
µ
F
0.01
µ
F
Discharge
Trigger
Load
VCC (5.0 V to 15 V)
0.01
µ
F
Control
Output
1/2
MC3456 1/2
MC3456 1/2
MC3456
MC3456
9
MOTOROLA ANALOG IC DEVICE DATA
P SUFFIX
PLASTIC PACKAGE
CASE 646–06
ISSUE L
D SUFFIX
PLASTIC PACKAGE
CASE 751–05
(SO–14)
ISSUE N
OUTLINE DIMENSIONS
NOTES:
1. LEADS WITHIN 0.13 (0.005) RADIUS OF TRUE
POSITION AT SEATING PLANE AT MAXIMUM
MATERIAL CONDITION.
2. DIMENSION L TO CENTER OF LEADS WHEN
FORMED PARALLEL.
3. DIMENSION B DOES NOT INCLUDE MOLD
FLASH.
4. ROUNDED CORNERS OPTIONAL.
17
14 8
B
A
F
HG D K
C
N
L
J
M
SEATING
PLANE
DIM MIN MAX MIN MAX
MILLIMETERSINCHES
A0.715 0.770 18.16 19.56
B0.240 0.260 6.10 6.60
C0.145 0.185 3.69 4.69
D0.015 0.021 0.38 0.53
F0.040 0.070 1.02 1.78
G0.100 BSC 2.54 BSC
H0.052 0.095 1.32 2.41
J0.008 0.015 0.20 0.38
K0.115 0.135 2.92 3.43
L0.300 BSC 7.62 BSC
M0 10 0 10
N0.015 0.039 0.39 1.01
____
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15 (0.006)
PER SIDE.
5. DIMENSION D DOES NOT INCLUDE DAMBAR
PROTRUSION. ALLOWABLE DAMBAR
PROTRUSION SHALL BE 0.127 (0.005) TOTAL
IN EXCESS OF THE D DIMENSION AT
MAXIMUM MATERIAL CONDITION.
SEATING
PLANE
14
58
C
K
4X P
A0.25 (0.010) MTBSS
0.25 (0.010) MBM
8X D
R
MJ
X 45
_
_
F
–A–
–B–
–T–
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A4.80 5.00 0.189 0.196
B3.80 4.00 0.150 0.157
C1.35 1.75 0.054 0.068
D0.35 0.49 0.014 0.019
F0.40 1.25 0.016 0.049
G1.27 BSC 0.050 BSC
J0.18 0.25 0.007 0.009
K0.10 0.25 0.004 0.009
M0 7 0 7
P5.80 6.20 0.229 0.244
R0.25 0.50 0.010 0.019
____
G
MC3456
10 MOTOROLA ANALOG IC DEVICE DATA
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specifically disclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including “Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
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MC3456/D
*MC3456/D*
◊
