ON MC74HC4538A Dual precision monostable multivibrator Datasheet

MC74HC4538A
Dual Precision Monostable
Multivibrator (Retriggerable,
Resettable)
The MC74HC4538A is identical in pinout to the MC14538B.
The device inputs are compatible with standard CMOS outputs; with
pullup resistors, they are compatible with LSTTL outputs.
This dual monostable multivibrator may be triggered by either the
positive or the negative edge of an input pulse, and produces
a precision output pulse over a wide range of pulse widths. Because
the device has conditioned trigger inputs, there are no trigger−input
rise and fall time restrictions. The output pulse width is determined by
the external timing components, Rx and Cx. The device has a reset
function which forces the Q output low and the Q output high,
regardless of the state of the output pulse circuitry.
Features
• Unlimited Rise and Fall Times Allowed on the Trigger Inputs
• Output Pulse is Independent of the Trigger Pulse Width
• ± 10% Guaranteed Pulse Width Variation from Part to Part
•
•
•
•
•
•
•
•
•
(Using the Same Test Jig)
Output Drive Capability: 10 LSTTL Loads
Outputs Directly Interface to CMOS, NMOS and TTL
Operating Voltage Range: 3.0 to 6.0 V
Low Input Current: 1.0 mA
High Noise Immunity Characteristic of CMOS Devices
In Compliance with the Requirements Defined by JEDEC Standard
No. 7 A
Chip Complexity: 145 FETs or 36 Equivalent Gates
NLV Prefix for Automotive and Other Applications Requiring
Unique Site and Control Change Requirements; AEC−Q100
Qualified and PPAP Capable
These Devices are Pb−Free, Halogen Free and are RoHS Compliant
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SOIC−16
D SUFFIX
CASE 751B
TSSOP−16
DT SUFFIX
CASE 948F
PIN ASSIGNMENT
GND
1
16
CX1/RX1
2
15
GND
RESET 1
3
14
CX2/RX2
A1
4
13
RESET 2
B1
5
12
A2
Q1
6
11
B2
Q1
7
10
Q2
GND
8
9
Q2
VCC
MARKING DIAGRAMS
16
HC4538AG
AWLYWW
1
SOIC−16
16
HC45
38A
ALYWG
G
1
TSSOP−16
A
L, WL
Y, YY
W, WW
G or G
= Assembly Location
= Wafer Lot
= Year
= Work Week
= Pb−Free Package
(Note: Microdot may be in either location)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 2 of this data sheet.
© Semiconductor Components Industries, LLC, 2014
August, 2014 − Rev. 15
1
Publication Order Number:
MC74HC4538A/D
MC74HC4538A
FUNCTION TABLE
Inputs
Reset
A
Outputs
B
Q
Q
H
H
H
L
H
H
X
H
L
X
Not Triggered
Not Triggered
H
H
L,H,
L
H
L,H,
Not Triggered
Not Triggered
L
X
X
X
X
L
H
Not Triggered
CX 1
RX 1
VCC
1
TRIGGER
INPUTS
A1
B1
RESET 1
2
4
6
5
7
Q1
Q1
PIN 16 = VCC
PIN 8 = GND
RX AND CX ARE EXTERNAL COMPONENTS
PIN 1 AND PIN 15 MUST BE HARD WIRED TO GND
3
CX 2
RX 2
VCC
15 14
TRIGGER
INPUTS
A2
B2
RESET 2
12
10
11
9
Q2
Q2
13
Figure 1. Logic Diagram
ORDERING INFORMATION
Package
Shipping†
MC74HC4538ADG
SOIC−16
(Pb−Free)
48 Units / Rail
MC74HC4538ADR2G
SOIC−16
(Pb−Free)
2500 / Tape & Reel
NLV74HC4538ADR2G*
SOIC−16
(Pb−Free)
2500 / Tape & Reel
MC74HC4538ADTR2G
TSSOP−16
(Pb−Free)
2500 / Tape & Reel
NLVHC4538ADTR2G*
TSSOP−16
(Pb−Free)
2500 / Tape & Reel
Device
†For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging
Specifications Brochure, BRD8011/D.
*NLV Prefix for Automotive and Other Applications Requiring Unique Site and Control Change Requirements; AEC−Q100 Qualified and PPAP
Capable
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2
MC74HC4538A
MAXIMUM RATINGS
Symbol
VCC
Parameter
Value
Unit
−0.5 to +7.0
V
−0.5 ≤ VI ≤ VCC + 0.5
V
−0.5 ≤ VO ≤ VCC + 0.5
V
±20
±30
mA
±25
mA
DC Supply Voltage
VI
DC Input Voltage
VO
DC Output Voltage
IIK
DC Input Diode Current
IOK
DC Output Diode Current
(Note 1)
A, B, Reset
CX, RX
IO
DC Output Sink Current
±25
mA
ICC
DC Supply Current per Supply Pin
±100
mA
IGND
DC Ground Current per Ground Pin
±100
mA
TSTG
Storage Temperature Range
−65 to +150
_C
TL
Lead temperature, 1 mm from Case for 10 Seconds
260
_C
TJ
Junction temperature under Bias
+150
_C
qJA
Thermal resistance
SOIC
TSSOP
112
148
_C/W
PD
Power Dissipation in Still Air at 85_C
SOIC
TSSOP
500
450
mW
MSL
Moisture Sensitivity
FR
Flammability Rating
VESD
ILatchup
Level 1
Oxygen Index: 30% − 35%
ESD Withstand Voltage
Latchup Performance
UL−94−VO (0.125 in)
Human Body Model (Note 2)
Machine Model (Note 3)
Charged Device Model (Note 4)
Above VCC and Below GND at 85_C (Note 5)
> 2000
> 100
> 500
V
±300
mA
Stresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionality
should not be assumed, damage may occur and reliability may be affected.
1. IO absolute maximum rating must be observed.
2. Tested to EIA/JESD22−A114−A.
3. Tested to EIA/JESD22−A115−A.
4. Tested to JESD22−C101−A.
5. Tested to EIA/JESD78.
RECOMMENDED OPERATING CONDITIONS
Symbol
VCC
Vin, Vout
Parameter
DC Supply Voltage (Referenced to GND)
DC Input Voltage, Output Voltage (Referenced to GND)
TA
Operating Temperature, All Package Types
tr, tf
Input Rise and Fall Time
(Figure 6)
External Timing Resistor
Cx
External Timing Capacitor
Max
Unit
2.0
6.0
V
0
VCC
V
–55
+125
_C
VCC = 2.0 V
VCC = 4.5 V
VCC = 6.0 V
0
0
0
−
1000
500
400
No Limit
ns
VCC < 4.5 V
VCC ≥ 4.5 V
1.0
2.0
†
†
kW
0
†
mF
A or B (Figure 4)
Rx
Min
Functional operation above the stresses listed in the Recommended Operating Ranges is not implied. Extended exposure to stresses beyond
the Recommended Operating Ranges limits may affect device reliability.
†The maximum allowable values of Rx and Cx are a function of the leakage of capacitor Cx, the leakage of the HC4538A, and leakage due to board layout
and surface resistance. For most applications, Cx/Rx should be limited to a maximum value of 10 mF/1.0 MW. Values of Cx > 1.0 mF may cause a
problem during power down (see Power Down Considerations). Susceptibility to externally induced noise signals may occur for Rx > 1.0 MW.
6. Unused inputs may not be left open. All inputs must be tied to a high−logic voltage level or a low−logic input voltage level.
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MC74HC4538A
DC CHARACTERISTICS
Guaranteed Limits
Symbol
Parameter
≤ 85_C
–55 to 25_C
Test Conditions
VCC
V
Min
1.5
3.15
4.2
Typ
Max
Min
Typ
≤ 125_C
Max
VIH
Minimum
High−Level
Input Voltage
Vout = 0.1 V or VCC –
0.1 V
|Iout| ≤ 20 mA
2.0
4.5
6.0
VIL
Maximum
Low−Level
Input Voltage
Vout = 0.1 V or VCC –
0.1 V
|Iout| ≤ 20 mA
2.0
4.5
6.0
VOH
Minimum
High−Level
Output Voltage
Vin = VIH or VIL
|Iout| ≤ 20 mA
2.0
4.5
6.0
1.9
4.4
5.9
1.9
4.4
5.9
1.9
4.4
5.9
4.5
6.0
3.98
5.48
3.84
5.34
3.7
5.2
Vin = VIH or VIL
|Iout| ≤ − 4.0 mA
|Iout| ≤ − 5.2 mA
VOL
Maximum
Low−Level
Output Voltage
Vin = VIH or VIL
|Iout| ≤ 20 mA
1.5
3.15
4.2
Min
Typ
Max
1.5
3.15
4.2
0.5
1.35
1.8
0.5
1.35
1.8
Unit
V
0.5
1.35
1.8
V
V
2.0
4.5
6.0
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Vin = VIH or VIL
|Iout| ≤ 4.0 mA
|Iout| ≤ 5.2 mA
4.5
6.0
0.26
0.26
0.33
0.33
0.4
0.4
V
Iin
Maximum Input
Leakage Current
(A, B, Reset)
Vin = VCC or GND
6.0
±0.1
±1.0
±1.0
mA
Iin
Maximum Input
Leakage Current
(Rx, Cx)
Vin = VCC or GND
6.0
± 50
±500
±500
nA
ICC
Maximum
Quiescent
Supply Current
(per package)
Standby State
Vin = VCC or GND
Q1 and Q2 = Low
Iout = 0 mA
6.0
130
220
350
mA
Maximum Supply
Current
(per package)
Active State
Vin = VCC or GND
Q1 and Q2 = High
Iout = 0 mA
Pins 2 and 14 = 0.5
VCC
ICC
6.0
25_C
–45_C to 85_C
400
600
–55_C to 125_C
800
mA
Product parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Product
performance may not be indicated by the Electrical Characteristics if operated under different conditions.
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MC74HC4538A
AC CHARACTERISTICS (CL = 50 pF, Input tr = tf = 6.0 ns)
Guaranteed Limits
VCC
V
Parameter
Symbol
≤ 85_C
–55 to 25_C
Min
Max
Min
Max
≤ 125_C
Min
Max
Unit
tPLH
Maximum Propagation Delay
Input A or B to Q
(Figures 5 and 7)
2.0
4.5
6.0
175
35
30
220
44
37
265
53
45
ns
tPHL
Maximum Propagation Delay
Input A or B to NQ
(Figures 5 and 7)
2.0
4.5
6.0
195
39
33
245
49
42
295
59
50
ns
tPHL
Maximum Propagation Delay
Reset to Q
(Figures 6 and 7)
2.0
4.5
6.0
175
35
30
220
44
37
265
53
45
ns
tPLH
Maximum Propagation Delay
Reset to NQ
(Figures 6 and 7)
2.0
4.5
6.0
175
35
30
220
44
37
265
53
45
ns
tTLH,
tTHL
Maximum Output Transition Time, Any Output
(Figures 6 and 7)
2.0
4.5
6.0
75
15
13
95
19
16
110
22
19
ns
−
10
25
10
25
10
25
pF
Cin
Maximum Input Capacitance
(A. B, Reset)
(Cx, Rx)
Typical @ 25°C, VCC = 5.0 V
CPD
150
Power Dissipation Capacitance (per Multivibrator)*
*Used to determine the no−load dynamic power consumption: PD = CPD VCC
2f
pF
+ ICC VCC .
TIMING CHARACTERISTICS (Input tr = tf = 6.0 ns)
Guaranteed Limits
Parameter
Symbol
≤ 85_C
–55 to 25_C
Min
Max
Min
Max
≤ 125_C
Min
Max
Unit
trr
Minimum Retrigger Time, Input A or B
(Figure 6) (Note 7)
2.0
4.5
6.0
−
−
−
−
−
−
trec
Minimum Recovery Time, Inactive to A or B
(Figure 6)
2.0
4.5
6.0
0
0
0
0
0
0
0
0
0
ns
tw
Minimum Pulse Width, Input A or B
(Figure 5)
2.0
4.5
6.0
60
12
10
75
15
13
90
18
15
ns
tw
Minimum Pulse Width, Reset
(Figure 6)
2.0
4.5
6.0
60
12
10
75
15
13
90
18
15
ns
Maximum Input Rise and Fall Times, Reset
(Figure 6)
2.0
4.5
6.0
A or B
(Figure 6)
2.0
4.5
6.0
tr, tf
7.
VCC
V
t rr(ns) +
V CC (volts) C x (pF)
30.5
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5
1000
500
400
ns
1000
500
400
No Limit
1000
500
400
ns
MC74HC4538A
OUTPUT PULSE WIDTH CHARACTERISTICS (Rx = 10 kW, Cx = 0.1 mF, CL = 50 pF)
Conditions
Symbol
Parameter
Guaranteed Limits
Timing Components
Output Pulse Width (Note 8)
(Figures 5 and 6)
τ
Pulse Width Match Between
Circuits in the same Package
Rx = 10 kW,
Cx = 0.1 mF
≤ 85_C
–55 to 25_C
VCC
V
≤ 125_C
Min
Max
Min
Max
Min
Max
Unit
0.63
0.77
0.6
0.8
0.59
0.81
ms
5.0
Pulse Width Match Variation
(Part to Part) (Note 10)
±5.0
%
±10
%
OUTPUT PULSE WIDTH CHARACTERISTICS (Rx = 100 kW, Cx = 1 nF, CL = 50 pF)
Conditions
Symbol
Parameter
Timing
Components
VCC
V
Output Pulse Width (Note 9)
τ
Pulse Width Match Between Circuits in the
same Package
Pulse Width Match Variation (Part to Part)
(Note 10)
Rx = 100 kW,
Cx = 1 nF
5.0
Guaranteed Limits
Ambient
Temperature
Min
Typ
Max
Unit
25°C
−
79
−
ms
−55 to 125°C
−5.0
−
+5.0
%
−55 to 125°C
−10
−
+10
%
−
Temperature Variance
−55 to 125°C
−
+0.05
−
ms/°C
−
Power Supply Variance
−55 to 125°C
−
−8.0
−
ms/V
8. τ = kRxCx and k = 0.7 for the output pulse width corresponding to Rx = 10 kW, Cx = 0.1 mF.
9. τ = kRxCx and k = 0.79 for the output pulse width corresponding to Rx = 100 kW, Cx = 1 nF.
10. Pulse width match variation between ICs (part−to−part) is defined with identical Rx, Cx, VCC and a specific temperature.
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MC74HC4538A
0.70
10 s
TA = 25°C
OUTPUT PULSE WIDTH (τ)
k, OUTPUT PULSE WIDTH CONSTANT
(TYPICAL)
TYPICAL CHARACTERISTICS
0.65
0.60
0.55
0.50
1
2
3
4
5
6
VCC, POWER SUPPLY VOLTAGE (VOLTS)
1s
VCC = 5 V, TA = 25°C
100 ms
10 ms
1 ms
100 ms
1 MW
10 ms
100 kW
1 ms
10 kW
1 kW
100 ns
0.00001 0.0001
7
Figure 2. Typical Output Pulse Width Constant,
k, versus Supply Voltage
(For output pulse widths > 100 ms: τ = kRxCx)
0.001
0.01
0.1
CAPACITANCE (mF)
1
10
Figure 3. Output Pulse Width versus Timing
Capacitance
OUTPUT PULSE WIDTH (τ)
(NORMALIZED TO 5 V NUMBER)
1.30
TA = 25°C
Rx = 1 MW
Cx = 0.1 mF
1.20
1.10
1.00
Rx = 100 kW
Cx = 1000 pF
0.90
0.80
1
2
3
4
5
6
VCC, POWER SUPPLY VOLTAGE (VOLTS)
7
Figure 4. Normalized Output Pulse Width versus
Power Supply Voltage
1.025
1.05
OUTPUT PULSE WIDTH (τ)
(NORMALIZED TO 25_C NUMBER)
OUTPUT PULSE WIDTH (τ)
(NORMALIZED TO 25_C NUMBER)
1.075
VCC = 6 V
1.025
1.0
0.975
VCC = 3 V
0.95
−75 −50
−25
0
25
50
75
100
125
VCC = 5.5 V
1.02
VCC = 5 V
1.015
VCC = 4.5 V
1.01
1.005
1.00
25
150
TA, AMBIENT TEMPERATURE (°C)
50
75
100
125
TA, AMBIENT TEMPERATURE (°C)
Figure 5. Normalized Output Pulse Width
versus Power Supply Voltage
Figure 6. Normalized Output Pulse Width versus
Power Supply Voltage
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MC74HC4538A
tw(H)
VCC
50%
A
GND
tw(L)
VCC
B
50%
GND
τ
tPLH
τ
tPLH
50%
Q
τ
tPHL
τ
tPHL
Q
50%
Figure 7. Switching Waveform
tr
tf
VCC
90%
10%
A
GND
trr
VCC
50%
GND
B
tf
tf
GND
trec
τ + trr
tPHL
90%
50%
50%
10%
Q
tTHL
Q
10%
tw(L)
tTLH
VCC
90%
50%
RESET
tPLH
90%
10%
50%
Figure 8. Switching Waveform
TEST POINT
OUTPUT
DEVICE
UNDER
TEST
CL *
*Includes all probe and jig capacitance
Figure 9. Test Circuit
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8
(RETRIGGERED PULSE)
MC74HC4538A
PIN DESCRIPTIONS
INPUTS
capacitors (see the Block Diagram). Polystyrene capacitors
are recommended for optimum pulse width control.
Electrolytic capacitors are not recommended due to high
leakages associated with these type capacitors.
A1, A2 (Pins 4, 12)
Positive−edge trigger inputs. A rising−edge signal on
either of these pins triggers the corresponding multivibrator
when there is a high level on the B1 or B2 input.
GND (Pins 1 and 15)
External ground. The external timing capacitors discharge
to ground through these pins.
B1, B2 (Pins 5, 11)
Negative−edge trigger inputs. A falling−edge signal on
either of these pins triggers the corresponding multivibrator
when there is a low level on the A1 or A2 input.
OUTPUTS
Q1, Q2 (Pins 6, 10)
Reset 1, Reset 2 (Pins 3, 13)
Noninverted monostable outputs. These pins (normally
low) pulse high when the multivibrator is triggered at either
the A or the B input. The width of the pulse is determined by
the external timing components, RX and CX.
Reset inputs (active low). When a low level is applied to
one of these pins, the Q output of the corresponding
multivibrator is reset to a low level and the Q output is set to
a high level.
Q1, Q2 (Pins 7, 9)
CX1/RX1 and CX2/RX2 (Pins 2 and 14)
Inverted monostable outputs. These pins (normally high)
pulse low when the multivibrator is triggered at either the A
or the B input. These outputs are the inverse of Q1 and Q2.
External timing components. These pins are tied to the
common points of the external timing resistors and
RxCx
UPPER
REFERENCE
CIRCUIT
−
+ Vre,
UPPER
VCC
VCC
OUTPUT
LATCH
LOWER
REFERENCE
CIRCUIT
M1
2 kW
−
+
M2
Q
Vre,
LOWER
M3
Q
TRIGGER
CONTROL CIRCUIT
A
C
CB
B
Q
TRIGGER CONTROL
RESET CIRCUIT
R
RESET
POWER
ON
RESET
RESET LATCH
Figure 10. Logic Detail (1/2 the Device)
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MC74HC4538A
CIRCUIT OPERATION
TRIGGER OPERATION
Figure 11 shows the HC4538A configured in the
retriggerable mode. Briefly, the device operates as follows
(refer to Figure 10): In the quiescent state, the external
timing capacitor, Cx, is charged to VCC. When a trigger
occurs, the Q output goes high and Cx discharges quickly to
the lower reference voltage (Vref Lower [ 1/3 VCC). Cx
then charges, through Rx, back up to the upper reference
voltage (Vref Upper [ 2/3 VCC), at which point the
one−shot has timed out and the Q output goes low.
The following, more detailed description of the circuit
operation refers to both the logic detail (Figure 10) and the
timing diagram (Figure 11).
The HC4538A is triggered by either a rising−edge signal
at input A (#7) or a falling−edge signal at input B (#8), with
the unused trigger input and the Reset input held at the
voltage levels shown in the Function Table. Either trigger
signal will cause the output of the trigger−control circuit to
go high (#9).
The trigger−control circuit going high simultaneously
initiates two events. First, the output latch goes low, thus
taking the Q output of the HC4538A to a high state (#10).
Second, transistor M3 is turned on, which allows the
external timing capacitor, Cx, to rapidly discharge toward
ground (#11). (Note that the voltage across Cx appears at the
input of both the upper and lower reference circuit
comparator).
When Cx discharges to the reference voltage of the lower
reference circuit (#12), the outputs of both reference circuits
will be high (#13). The trigger−control reset circuit goes high,
resetting the trigger−control circuit flip−flop to a low state
(#14). This turns transistor M3 off again, allowing Cx to begin
to charge back up toward VCC, with a time constant t = RxCx
(#15). Once the voltage across Cx charges to above the lower
reference voltage, the lower reference circuit will go low
allowing the monostable multivibrator to be retriggered.
QUIESCENT STATE
In the quiescent state, before an input trigger appears, the
output latch is high and the reset latch is high (#1 in Figure
11). Thus the Q output (pin 6 or 10) of the monostable
multivibrator is low (#2, Figure 11).
The output of the trigger−control circuit is low (#3), and
transistors M1, M2, and M3 are turned off. The external
timing capacitor, Cx, is charged to VCC (#4), and both the
upper and lower reference circuit has a low output (#5).
In addition, the output of the trigger−control reset circuit
is low.
QUIESCENT
STATE
TRIGGER CYCLE
(A INPUT)
TRIGGER CYCLE
(B INPUT)
RESET
RETRIGGER
trr
7
TRIGGER INPUT A
(PIN 4 OR 12)
TRIGGER INPUT B
(PIN 5 OR 11)
8
24
9
TRIGGER-CONTROL
CIRCUIT OUTPUT
3
14
11
4
RX/CX INPUT
(PIN 2 OR 14)
15
21
17
23
12
Vref LOWER
UPPER REFERENCE
CIRCUIT
5
LOWER REFERENCE
CIRCUIT
6
Vref UPPER
13
25
18
13
16
RESET INPUT
(PIN 3 OR 13)
20
1
RESET LATCH
22
10
Q OUTPUT
(PIN 6 OR 10)
2
19
τ
τ
Figure 11. Timing Diagram
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10
τ + trr
MC74HC4538A
occurs, the output of the reset latch goes low (#22), turning
on transistor M1. Thus Cx is allowed to quickly charge up to
VCC (#23) to await the next trigger signal.
On power up of the HC4538A the power−on reset circuit
will be high causing a reset condition. This will prevent the
trigger−control circuit from accepting a trigger input during
this state. The HC4538A’s Q outputs are low and the Q not
outputs are high.
When Cx charges up to the reference voltage of the upper
reference circuit (#17), the output of the upper reference
circuit goes low (#18). This causes the output latch to toggle,
taking the Q output of the HC4538A to a low state (#19), and
completing the time−out cycle.
POWER−DOWN CONSIDERATIONS
Large values of Cx may cause problems when powering
down the HC4538A because of the amount of energy stored
in the capacitor. When a system containing this device is
powered down, the capacitor may discharge from VCC
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 VCC power supply
must not be faster than t = VCCCx /(30 mA). For example,
if VCC = 5.0 V and Cx = 15 mF, the VCC supply must turn off
no faster than t = (5.0 V)(15 mF)/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 VCC to zero volts occurs,
the HC4538A may sustain damage. To avoid this possibility,
use an external damping diode, Dx, connected as shown in
Figure 12. Best results can be achieved if diode Dx is chosen
to be a germanium or Schottky type diode able to withstand
large current surges.
RETRIGGER OPERATION
When used in the retriggerable mode (Figure 13), the
HC4538A may be retriggered during timing out of the
output pulse at any time after the trigger−control circuit
flip−flop has been reset (#24), and the voltage across Cx is
above the lower reference voltage. As long as the Cx voltage
is below the lower reference voltage, the reset of the
flip−flop is high, disabling any trigger pulse. This prevents
M3 from turning on during this period resulting in an output
pulse width that is predictable.
The amount of undershoot voltage on RxCx during the
trigger mode is a function of loop delay, M3 conductivity,
and VDD. Minimum retrigger time, trr (Figure 7), is a
function of 1) time to discharge Rx Cx from VDD to lower
reference voltage (Tdischarge); 2) loop delay (Tdelay); 3)
time to charge Rx Cx from the undershoot voltage back to the
lower reference voltage (Tcharge).
Figure 14 shows the device configured in the
non−retriggerable mode.
For additional information, please see Application Note
(AN1558/D) titled Characterization of Retrigger Time in
the HC4538A Dual Precision Monostable Multivibrator.
RESET AND POWER ON RESET OPERATION
A low voltage applied to the Reset pin always forces the
Q output of the HC4538A to a low state.
The timing diagram illustrates the case in which reset
occurs (#20) while Cx is charging up toward the reference
voltage of the upper reference circuit (#21). When a reset
DX
CX
VCC
RX
Q
A
B
Q
RESET
Figure 12. Discharge Protection During Power Down
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11
MC74HC4538A
TYPICAL APPLICATIONS
CX
RISING−EDGE
TRIGGER
RX
CX
RX
RISING−EDGE
TRIGGER
VCC
Q
A
B
VCC
Q
A
Q
B
Q
B = VCC
RESET = VCC
RESET = VCC
CX
RX
CX
FALLING−EDGE
TRIGGER
VCC
A = GND
VCC
Q
Q
B
RX
A
B
Q
Q
FALLING−EDGE
TRIGGER
RESET = VCC
RESET = VCC
Figure 13. Retriggerable Monostable Circuitry
Figure 14. Non−retriggerable Monostable Circuitry
GND
N/C
A = GND
VCC
RX CX
Q
N/C
B
Q
RESET
N/C
Figure 15. Connection of Unused Section
ONE−SHOT SELECTION GUIDE
100 ns
MC14528B
MC14536B
MC14538B
MC14541B
HC4538A*
1 ms 10 ms 100 ms 1 ms 10 ms 100 ms 1 s
10 s
23 HR
5 MIN
*Limited operating voltage (2 −6 V)
TOTAL OUTPUT PULSE WIDTH RANGE
RECOMMENDED PULSE WIDTH RANGE
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12
MC74HC4538A
PACKAGE DIMENSIONS
TSSOP−16
CASE 948F
ISSUE B
16X K REF
0.10 (0.004)
0.15 (0.006) T U
M
T U
S
V
S
S
K
ÉÉÉ
ÇÇÇ
ÇÇÇ
ÉÉÉ
K1
2X
L/2
16
9
J1
B
−U−
L
SECTION N−N
J
PIN 1
IDENT.
N
0.25 (0.010)
8
1
M
0.15 (0.006) T U
S
A
−V−
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A DOES NOT INCLUDE MOLD
FLASH. PROTRUSIONS OR GATE BURRS.
MOLD FLASH OR GATE BURRS SHALL NOT
EXCEED 0.15 (0.006) PER SIDE.
4. DIMENSION B DOES NOT INCLUDE
INTERLEAD FLASH OR PROTRUSION.
INTERLEAD FLASH OR PROTRUSION SHALL
NOT EXCEED 0.25 (0.010) PER SIDE.
5. DIMENSION K DOES NOT INCLUDE
DAMBAR PROTRUSION. ALLOWABLE
DAMBAR PROTRUSION SHALL BE 0.08
(0.003) TOTAL IN EXCESS OF THE K
DIMENSION AT MAXIMUM MATERIAL
CONDITION.
6. TERMINAL NUMBERS ARE SHOWN FOR
REFERENCE ONLY.
7. DIMENSION A AND B ARE TO BE
DETERMINED AT DATUM PLANE −W−.
N
F
DETAIL E
−W−
C
0.10 (0.004)
−T− SEATING
PLANE
H
D
DETAIL E
G
DIM
A
B
C
D
F
G
H
J
J1
K
K1
L
M
SOLDERING FOOTPRINT*
7.06
1
0.65
PITCH
16X
0.36
16X
1.26
DIMENSIONS: MILLIMETERS
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
http://onsemi.com
13
MILLIMETERS
MIN
MAX
4.90
5.10
4.30
4.50
−−−
1.20
0.05
0.15
0.50
0.75
0.65 BSC
0.18
0.28
0.09
0.20
0.09
0.16
0.19
0.30
0.19
0.25
6.40 BSC
0_
8_
INCHES
MIN
MAX
0.193 0.200
0.169 0.177
−−− 0.047
0.002 0.006
0.020 0.030
0.026 BSC
0.007
0.011
0.004 0.008
0.004 0.006
0.007 0.012
0.007 0.010
0.252 BSC
0_
8_
MC74HC4538A
PACKAGE DIMENSIONS
SOIC−16
CASE 751B−05
ISSUE K
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.
−A−
16
9
−B−
1
P
8 PL
0.25 (0.010)
8
B
M
S
DIM
A
B
C
D
F
G
J
K
M
P
R
G
R
K
F
X 45 _
C
−T−
SEATING
PLANE
J
M
D
MILLIMETERS
MIN
MAX
9.80
10.00
3.80
4.00
1.35
1.75
0.35
0.49
0.40
1.25
1.27 BSC
0.19
0.25
0.10
0.25
0_
7_
5.80
6.20
0.25
0.50
INCHES
MIN
MAX
0.386
0.393
0.150
0.157
0.054
0.068
0.014
0.019
0.016
0.049
0.050 BSC
0.008
0.009
0.004
0.009
0_
7_
0.229
0.244
0.010
0.019
16 PL
0.25 (0.010)
M
T B
S
A
S
SOLDERING FOOTPRINT*
8X
6.40
16X
1
1.12
16
16X
0.58
1.27
PITCH
8
9
DIMENSIONS: MILLIMETERS
*For additional information on our Pb−Free strategy and soldering
details, please download the ON Semiconductor Soldering and
Mounting Techniques Reference Manual, SOLDERRM/D.
ON Semiconductor and the
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MC74HC4538A/D