1. General description
The 74HC4538; 74HCT4538 are high-speed Si-gate CMOS devices and are pin
compatible with Low-power Schottky TTL (LSTTL). They are specified in compliance with
JEDEC standard no. 7A.
The 74HC4538; 74HCT4538 are dual retriggerable-resettable monostable multivibrators.
Each multivibrator has an active LOW trigger/retrigger input (nA), an active HIGH
trigger/retrigger input (nB), an overriding active LOW direct reset input (nCD), an output
(nQ) and its complement (nQ), and two pins (nREXT/CEXT and nCEXT) for connecting
the external timing components CEXT and REXT. Typical pulse width variation over the
specified temperature range is ±0.2 %.
The multivibrator may be triggered by either the positive or the negative edges of the input
pulse. The duration and accuracy of the output pulse are determined by the external
timing components CEXT and REXT. The output pulse width (tW) is equal to
0.7 ×REXT ×CEXT. The linear design techniques guarantee precise control of the output
pulse width. A LOW level at nCD terminates the output pulse immediately. Schmitt trigger
action on pins nA and nB makes the circuit highly tolerant of slower rise and fall times.
2. Features
nTolerant of slow trigger rise and fall times
nSeparate reset inputs
nTriggering from falling or rising edge
nMultiple package options
nESD protection:
uHBM JESD22-A114E exceeds 2000 V
uMM JESD22-A115-A exceeds 200 V
nSpecified from 40 °Cto+85°C and from 40 °C to +125 °C
74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
Rev. 03 — 8 June 2009 Product data sheet
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 2 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
3. Ordering information
4. Functional diagram
Table 1. Ordering information
Type number Package
Temperature range Name Description Version
74HC4538N 40 °C to +125 °C DIP16 plastic dual in-line package; 16-leads (300 mil) SOT38-4
74HCT4538N
74HC4538D 40 °C to +125 °C SO16 plastic small outline package; 16 leads; body width 3.9 mm SOT109-1
74HCT4538D
74HC4538DB 40 °C to +125 °C SSOP16 plastic shrink small outline package; 16 leads;
body width 5.3 mm SOT338-1
74HCT4538DB
74HC4538PW 40 °C to +125 °C TSSOP16 plastic thin shrink small outline package; 16 leads;
body width 4.4 mm SOT403-1
74HCT4538PW
Fig 1. Functional diagram
001aae727
1A
1CEXT
1REXT/CEXT
7
6
1Q
1Q
1B
1CD
5
1
2
4
3
2A
2CEXT
2REXT/CEXT
9
10
2Q
2Q
2B
2CD
11
15
14
12
13
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 3 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
Fig 2. Logic diagram (one multivibrator)
mba338
Vref2
Vref1
GND
nCEXT
nREXT/CEXT
enable
enable
VCC
power-on reset
VCC
nCD
nB
nA
nQ
nQ
GND
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 4 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
5. Pinning information
5.1 Pinning
5.2 Pin description
Fig 3. Pin configuration for DIP16 and SO16 Fig 4. Pin configuration for SSOP16 and TSSOP16
74HC4538
74HCT4538
1CEXT VCC
1REXT/CEXT 2CEXT
1CD 2REXT/CEXT
1B 2CD
1A 2B
1Q 2A
1Q 2Q
GND 2Q
001aak190
1
2
3
4
5
6
7
8
10
9
12
11
14
13
16
15
74HC4538
74HCT4538
1CEXT VCC
1REXT/CEXT 2CEXT
1CD 2REXT/CEXT
1B 2CD
1A 2B
1Q 2A
1Q 2Q
GND 2Q
001aak191
1
2
3
4
5
6
7
8
10
9
12
11
14
13
16
15
Table 2. Pin description
Symbol Pin Description
1CEXT, 2CEXT 1, 15 external capacitor connection (always connected to ground)
1REXT/CEXT, 2REXT/CEXT 2, 14 external capacitor/resistor connection
1CD, 2CD 3, 13 direct reset input (active LOW)
1B, 2B 4, 12 input (LOW to HIGH triggered)
1A, 2A 5, 11 input (HIGH to LOW triggered)
1Q, 2Q 6, 10 output
1Q, 2Q 7, 9 complementary output (active LOW)
GND 8 ground (0 V)
VCC 16 supply voltage
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 5 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
6. Functional description
[1] H = HIGH voltage level; L = LOW voltage level; X = don’t care;
= positive-going transition; = negative-going transition;
= one HIGH level output pulse, with the pule width determined by CEXT and REXT;
= one LOW level output pulse, with the pulse width determined by CEXT and REXT.
Table 3. Function table
Inputs Outputs
nA nB nCD nQ nQ
LH
HH
XXLLH
(1) Positive edge triggering.
(2) Positive edge re-triggering (pulse lengthening).
(3) Negative edge triggering.
(4) Reset (pulse shortening).
(5) T = 0.7 × REXT × CEXT (see also Figure 6).
Fig 5. Timing diagram
001aae737
(1)
(3)
(5)
(4)
(1)(2)(1)
Vref1
T
Vref2 Vref2
Vref1
TT
nA input
nB input
nCD input
nREXT/CEXT input
nQ output
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 6 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
7. Limiting values
[1] The input and output voltage ratings may be exceeded if the input and output current ratings are observed.
[2] Ptot derates linearly with 12 mW/K above 70 °C.
[3] Ptot derates linearly with 8 mW/K above 70 °C.
[4] Ptot derates linearly with 5.5 mW/K above 60 °C.
Fig 6. Connection of the external timing components REXT and CEXT
001aak192
nQ
nCD
nQ
nREXT/CEXT
nB
nCEXT
GND VCC
REXT
CEXT
nA
T = 0.7 × REXT × CEXT
T
Table 4. Limiting values
In accordance with the Absolute Maximum Rating System (IEC 60134). Voltages are referenced to GND (ground = 0 V).
Symbol Parameter Conditions Min Max Unit
VCC supply voltage 0.5 +7.0 V
IIK input clamping current VI < 0.5 V or VI>V
CC + 0.5 V [1] -±20 mA
IOK output clamping current VO < 0.5 V or VO > VCC + 0.5 V [1] -±20 mA
IOoutput current VO = 0.5 V to VCC + 0.5 V - ±25 mA
ICC supply current - +50 mA
IGND ground current 50 - mA
Tstg storage temperature 65 +150 °C
Ptot total power dissipation Tamb = 40 °C to +125 °C
DIP16 package [2] - 750 mW
SO16 package [3] - 500 mW
(T)SSOP16 package [4] - 500 mW
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 7 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
8. Recommended operating conditions
9. Static characteristics
Table 5. Recommended operating conditions
Voltages are referenced to GND (ground = 0 V)
Symbol Parameter Conditions 74HC4538 74HCT4538 Unit
Min Typ Max Min Typ Max
VCC supply voltage 2.0 5.0 6.0 4.5 5.0 5.5 V
VIinput voltage 0 - VCC 0-V
CC V
VOoutput voltage 0 - VCC 0-V
CC V
Tamb ambient temperature 40 - +125 40 - +125 °C
t/V input transition rise and fall rate VCC = 2.0 V - - 625 - - - ns/V
VCC = 4.5 V - 1.67 139 - 1.67 139 ns/V
VCC = 6.0 V - - 83 - - - ns/V
Table 6. Static characteristics
At recommended operating conditions; voltages are referenced to GND (ground = 0 V).
Symbol Parameter Conditions 25 °C40 °C to +85 °C40 °C to +125 °C Unit
Min Typ Max Min Max Min Max
74HC4538
VIH HIGH-level
input voltage VCC = 2.0 V 1.5 1.2 - 1.5 - 1.5 - V
VCC = 4.5 V 3.15 2.4 - 3.15 - 3.15 - V
VCC = 6.0 V 4.2 3.2 - 4.2 - 4.2 - V
VIL LOW-level
input voltage VCC = 2.0 V - 0.8 0.5 - 0.5 - 0.5 V
VCC = 4.5 V - 2.1 1.35 - 1.35 - 1.35 V
VCC = 6.0 V - 2.8 1.8 - 1.8 - 1.8 V
VOH HIGH-level
output voltage VI = VIH or VIL
IO = 20 µA; VCC = 2.0 V 1.9 2.0 - 1.9 - 1.9 - V
IO = 20 µA; VCC = 4.5 V 4.4 4.5 - 4.4 - 4.4 - V
IO = 20 µA; VCC = 6.0 V 5.9 6.0 - 5.9 - 5.9 - V
IO = 4.0 mA; VCC = 4.5 V 3.98 4.32 - 3.84 - 3.7 - V
IO = 5.2 mA; VCC = 6.0 V 5.48 5.81 - 5.34 - 5.2 - V
VOL LOW-level
output voltage VI = VIH or VIL
IO = 20 µA; VCC = 2.0 V - 0 0.1 - 0.1 - 0.1 V
IO = 20 µA; VCC = 4.5 V - 0 0.1 - 0.1 - 0.1 V
IO = 20 µA; VCC = 6.0 V - 0 0.1 - 0.1 - 0.1 V
IO = 4.0 mA; VCC = 4.5 V - 0.15 0.26 - 0.33 - 0.4 V
IO = 5.2 mA; VCC = 6.0 V - 0.16 0.26 - 0.33 - 0.4 V
IIinput leakage
current VI = VCC or GND;
VCC = 6.0 V --±0.1 - ±1-±1µA
pin nREXT/CEXT;
VI= 2.0 V or GND; other
inputs at VCC or GND;
VCC = 6.0 V [1]
--±0.5 - ±5-±10 µA
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 8 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
[1] This measurement can only be carried out after a trigger pulse is applied.
ICC supply current VI = VCC or GND; IO=0A;
VCC = 6.0 V - - 8.0 - 80 - 160 µA
CIinput
capacitance - 3.5 - - - - - pF
74HCT4538
VIH HIGH-level
input voltage VCC = 4.5 V to 5.5 V 2.0 1.6 - 2.0 - 2.0 - V
VIL LOW-level
input voltage VCC = 4.5 V to 5.5 V - 1.2 0.8 - 0.8 - 0.8 V
VOH HIGH-level
output voltage VI = VIH or VIL; VCC = 4.5 V
IO = 20 µA 4.4 4.5 - 4.4 - 4.4 - V
IO = 4.0 mA 3.98 4.32 - 3.84 - 3.7 - V
VOL LOW-level
output voltage VI = VIH or VIL; VCC = 4.5 V
IO = 20 µA; VCC = 4.5 V - 0 0.1 - 0.1 - 0.1 V
IO = 4.0 mA; VCC = 4.5 V - 0.15 0.26 - 0.33 - 0.4 V
IIinput leakage
current VI = VCC or GND;
VCC = 5.5 V --±0.1 - ±1-±1µA
pin nREXT/CEXT;
VI= 2.0 V or GND; other
inputs at VCC or GND;
VCC = 5.5 V [1]
--±0.5 - ±5-±10 µA
ICC supply current VI = VCC or GND; IO=0A;
VCC = 5.5 V - - 8.0 - 80 - 160 µA
ICC additional
supply current VI=V
CC 2.1 V; IO=0A;
other inputs at VCC or GND;
VCC = 4.5 V to 5.5 V
pin nA, nB - 50 180 - 225 - 245 µA
pin nCD - 65 234 - 293 - 319 µA
CIinput
capacitance - 3.5 - - - - - pF
Table 6. Static characteristics
…continued
At recommended operating conditions; voltages are referenced to GND (ground = 0 V).
Symbol Parameter Conditions 25 °C40 °C to +85 °C40 °C to +125 °C Unit
Min Typ Max Min Max Min Max
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 9 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
10. Dynamic characteristics
Table 7. Dynamic characteristics
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 9.
Symbol Parameter Conditions 25 °C40 °C to
+85 °C40 °C to
+125 °CUnit
Min Typ[1] Max Min Max Min Max
74HC4538
tPLH LOW to HIGH
propagation
delay
nA, nB to nQ;
see Figure 7
VCC = 2.0 V - 85 265 - 330 - 400 ns
VCC = 4.5 V - 31 53 - 66 - 80 ns
VCC = 5.0 V; CL=15pF -27-----ns
VCC = 6.0 V - 25 45 - 56 - 68 ns
nCD to nQ; see Figure 7
VCC = 2.0 V - 83 265 - 340 - 400 ns
VCC = 4.5 V - 30 53 - 68 - 80 ns
VCC = 6.0 V - 24 45 - 58 - 68 ns
tPHL HIGH to LOW
propagation
delay
nA, nB to nQ;
see Figure 7
VCC = 2.0 V - 83 265 - 330 - 400 ns
VCC = 4.5 V - 30 53 - 66 - 80 ns
VCC = 5.0 V; CL=15pF -27-----ns
VCC = 6.0 V - 24 45 - 56 - 68 ns
nCD to nQ; see Figure 7
VCC = 2.0 V - 80 265 - 330 - 400 ns
VCC = 4.5 V - 29 53 - 66 - 80 ns
VCC = 6.0 V - 23 45 - 56 - 68 ns
tttransition time nQ and nQ; see Figure 7 [2]
VCC = 2.0 V - 19 75 - 95 - 119 ns
VCC = 4.5 V - 7 15 - 19 - 22 ns
VCC = 6.0 V - 6 13 - 16 - 19 ns
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 10 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
tWpulse width nA LOW; see Figure 8
VCC = 2.0 V 80 17 - 100 - 120 - ns
VCC = 4.5 V 16 6 - 20 - 24 - ns
VCC = 6.0 V 14 5 - 17 - 20 - ns
nB HIGH; see Figure 8
VCC = 2.0 V 80 17 - 100 - 120 - ns
VCC = 4.5 V 16 6 - 20 - 24 - ns
VCC = 6.0 V 14 5 - 17 - 20 - ns
nCD LOW; see Figure 8
VCC = 2.0 V 80 19 - 100 - 120 - ns
VCC = 4.5 V 16 7 - 20 - 24 - ns
VCC = 6.0 V 14 6 - 17 - 20 - ns
nQ and nQ HIGH or LOW;
see Figure 8
VCC = 5.0 V;
CEXT = 0.1 µF;
REXT = 10 k
630 700 770 602 798 595 805 µs
trec recovery time nCD to nA, nB;
see Figure 8
VCC = 2.0 V 35 6 - 45 - 55 - ns
VCC = 4.5 V 7 2 - 9 - 11 - ns
VCC = 6.0 V 6 2 - 8 - 9 - ns
trtrig retrigger time nA, nB; see Figure 8;
X=C
EXT / (4.5 × VCC)
VCC = 2.0 V - 455 + X -----ns
VCC = 4.5 V - 80 + X -----ns
VCC = 6.0 V - 55 + X -----ns
REXT externaltiming
resistor VCC = 2.0 V 10 - 1000 ----k
VCC = 5.0 V 2 - 1000 ----k
CEXT externaltiming
capacitor no limits
CPD power
dissipation
capacitance
per multivibrator;
VI= GND to VCC
[3] -136-----pF
Table 7. Dynamic characteristics
…continued
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 9.
Symbol Parameter Conditions 25 °C40 °C to
+85 °C40 °C to
+125 °CUnit
Min Typ[1] Max Min Max Min Max
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 11 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
74HCT4538
tPLH LOW to HIGH
propagation
delay
nA, nB to nQ;
see Figure 7
VCC = 4.5 V - 35 60 - 75 - 90 ns
VCC = 5.0 V; CL=15pF -30-----ns
nCD to nQ; see Figure 7
VCC = 4.5 V - 35 60 - 75 - 90 ns
tPHL HIGH to LOW
propagation
delay
nA, nB to nQ;
see Figure 7
VCC = 4.5 V - 35 60 - 75 - 90 ns
VCC = 5.0 V; CL=15pF -30-----ns
nCD to nQ; see Figure 7
VCC = 4.5 V - 35 60 - 75 - 90 ns
tttransition time nQ and nQ; see Figure 7 [2]
VCC = 4.5 V - 7 15 - 19 - 21 ns
tWpulse width nA LOW; see Figure 8
VCC = 4.5 V 20 11 - 25 - 30 - ns
nB HIGH; see Figure 8
VCC = 4.5 V 16 5 - 20 - 24 - ns
nCD LOW; see Figure 8
VCC = 4.5 V 20 11 - 25 - 30 - ns
nQ and nQ HIGH or LOW;
see Figure 8
VCC = 5.0 V;
CEXT = 0.1 µF;
REXT = 10 k
630 700 770 602 798 595 805 µs
trec recovery time nCD to nA, nB;
see Figure 8
VCC = 4.5 V 7 2 - 9 - 11 - ns
trtrig retrigger time nA, nB; see Figure 8;
X=C
EXT / (4.5 × VCC)
VCC = 4.5 V - 80 + X -----ns
REXT externaltiming
resistor VCC = 5.0 V 2 - 1000 ----k
CEXT externaltiming
capacitor VCC = 5.0 V no limits
Table 7. Dynamic characteristics
…continued
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 9.
Symbol Parameter Conditions 25 °C40 °C to
+85 °C40 °C to
+125 °CUnit
Min Typ[1] Max Min Max Min Max
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 12 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
[1] Typical values are measured at nominal supply voltage (VCC = 3.3 V and VCC = 5.0 V).
[2] tt is the same as tTHL and tTLH.
[3] CPD is used to determine the dynamic power dissipation (PD in µW).
PD=C
PD ×VCC2×fi×Σ(CL×VCC2×fo) + 0.48 × CEXT × VCC2× fo + D × 0.8 × VCC where:
fi= input frequency in MHz;
fo= output frequency in MHz;
Σ(CL×VCC2×fo) = sum of the outputs;
CL= output load capacitance in pF;
VCC = supply voltage in V;
D = duty cycle factor in %;
CEXT = external timing capacitance in pF.
11. Waveforms
CPD power
dissipation
capacitance
per multivibrator;
VI= GND to (VCC 1.5 V) [3] -138-----pF
Table 7. Dynamic characteristics
…continued
Voltages are referenced to GND (ground = 0 V); for test circuit see Figure 9.
Symbol Parameter Conditions 25 °C40 °C to
+85 °C40 °C to
+125 °CUnit
Min Typ[1] Max Min Max Min Max
Measurement points are given in Table 8.
Logic levels: VOL and VOH are typical output levels that occur with the output load.
Fig 7. Waveforms showing propagation delays and transition times
001aak194
VIVM
VX
VY
VY
VX
tPLH tPLH
tPHL tTHL tTLH tPLH
tPHL
tPHL
VMVM
VM
VM
VM
tW
tW
nB input
GND
VI
nA input
GND
VI
nCD input
GND
VOH
nQ output
VOL
VOH
nQ output
VOL
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 13 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
Measurement points are given in Table 8.
Logic levels: VOL and VOH are typical output levels that occur with the output load.
Fig 8. Waveforms showing nA, nB, nQ, nQ pulse widths, recovery and retrigger times
001aak195
nCD input
nA input
nB input
tWtrec tW
tW
VM
VI
VM
VM
VM
tW
trtrig
VI
VI
VOH
GND
VOL
nQ, nQ output
GND
GND
Table 8. Measurement points
Type Input Output
VMVMVXVY
74HC4538 0.5VCC 0.5VCC 0.1VCC 0.9VCC
74HCT4538 1.3 V 1.3 V 0.1VCC 0.9VCC
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 14 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
Test data is given in Table 9.
Definitions test circuit:
RT = Termination resistance should be equal to output impedance Zo of the pulse generator.
CL = Load capacitance including jig and probe capacitance.
RL = Load resistance.
S1 = Test selection switch
Fig 9. Test circuit for measuring switching times
VMVM
tW
tW
10 %
90 %
0 V
VI
VI
negative
pulse
positive
pulse
0 V
VMVM
90 %
10 %
tf
tr
tr
tf
001aad983
DUT
VCC VCC
VIVO
RT
RLS1
CL
open
G
Table 9. Test data
Type Input Load S1 position
VItr, tfCLRLtPHL, tPLH
74HC4538 VCC 6 ns 15 pF, 50 pF 1 kopen
74HCT4538 3 V 6 ns 15 pF, 50 pF 1 kopen
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 15 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
12. Application information
12.1 Power-down considerations
A large capacitor (CEXT) may cause problems when powering-down the monostable due
to energy stored in this capacitor. When a system containing this device is powered-down
or rapid decrease of VCC to zero occurs, the monostable may sustain damage, due to the
capacitor discharging through the input protection diodes. To avoid this possibility, use a
damping diode (DEXT) preferably a germanium or Schottky type diode able to withstand
large current surges and connect as shown in Figure 10
12.2 Graphs
Fig 10. Power-down protection circuit
001aak193
nREXT/CEXTnCEXT
GND VCC
REXT
DEXT
CEXT
VCC = 4.5 V; Tamb = 25 °C.
Fig 11. Typical pulse width accuracy versus external capacitance
001aak196
CEXT (F)
1010 105104
106
107
109108
1.0
1.2
0.8
1.6
0.6
normalized
K factor
(K)
0.70
0.84
0.56
1.12
0.42
REXT ×
CEXT
(tW)
1 k
2 k
5.6 k
51 k
1 M
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 16 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
VCC = 4.5 V; Tamb = 25 °C.
Fig 12. Typical pulse width accuracy versus external resistance
REXT ()
103106
105
104
001aak197
1.0
1.2
0.8
1.6
0.6
0.70
0.84
0.56
1.12
0.42
REXT ×
CEXT
(tW)
normalized
K factor
(K)
> 100 nF
1 nF
VCC = 4.5 V; REXT = 10 k; Tamb = 25 °C.
Fig 13. Typical pulse width accuracy versus external capacitance
001aak198
CEXT (F)
1010 105104
106
107
109108
1.0
1.2
0.8
1.6
0.6
normalized
K factor
(K)
0.70
0.84
0.56
1.12
0.42
REXT ×
CEXT
(tW)
REXT
+10 %
10 %
CEXT = 1 nF; Tamb = 25 °C.
Fig 14. Typical pulse width accuracy versus power supply
VCC (V)
156423
001aak199
0.77
0.91
0.63
1.19
0.49
REXT ×
CEXT
(tW)
1.1
1.3
0.9
1.7
0.7
normalized
K factor
(K) 5.6 k
2 k1 k
10 k
1 M
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 17 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
CEXT = 100 nF; Tamb = 25 °C.
Fig 15. Typical pulse width accuracy versus power supply
VCC (V)
156423
001aak200
0.77
0.91
0.63
1.19
0.49
REXT ×
CEXT
(tW)
1.1
1.3
0.9
1.7
0.7
normalized
K factor
(K)
5.6 k
2 k
1 k
1 M
VCC = 4.5 V; CEXT = 1 nF; Tamb = 25 °C.
Fig 16. Typical pulse width accuracy versus temperature
Tamb (°C)
50 100 150500
001aak201
0.77
0.91
0.63
1.19
0.49
REXT ×
CEXT
(tW)
1.1
1.3
0.9
1.7
0.7
normalized
K factor
(K)
5.6 k
2 k
1 k
1 M
VCC = 4.5 V; CEXT = 1 µF; Tamb = 25 °C.
Fig 17. Typical pulse width accuracy versus temperature
Tamb (°C)
50 100 150500
001aak202
0.77
0.91
0.63
1.19
0.49
REXT ×
CEXT
(tW)
1.1
1.3
0.9
1.7
0.7
normalized
K factor
(K)
1 k
2 k
5.6 k
1 M
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 18 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
13. Package outline
Fig 18. Package outline SOT38-4 (DIP16)
REFERENCES
OUTLINE
VERSION EUROPEAN
PROJECTION ISSUE DATE
IEC JEDEC JEITA
SOT38-4 95-01-14
03-02-13
MH
c
(e )
1
ME
A
L
seating plane
A1
wM
b1
b2
e
D
A2
Z
16
1
9
8
E
pin 1 index
b
0 5 10 mm
scale
Note
1. Plastic or metal protrusions of 0.25 mm (0.01 inch) maximum per side are not included.
UNIT A
max. 12 b1(1) (1) (1)
b2cD E e M Z
H
L
mm
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
A
min. A
max. bmax.
w
ME
e1
1.73
1.30 0.53
0.38 0.36
0.23 19.50
18.55 6.48
6.20 3.60
3.05 0.2542.54 7.62 8.25
7.80 10.0
8.3 0.764.2 0.51 3.2
inches 0.068
0.051 0.021
0.015 0.014
0.009
1.25
0.85
0.049
0.033 0.77
0.73 0.26
0.24 0.14
0.12 0.010.1 0.3 0.32
0.31 0.39
0.33 0.030.17 0.02 0.13
DIP16: plastic dual in-line package; 16 leads (300 mil) SOT38-4
74HC_HCT4538_3 © NXP B.V. 2009. All rights reserved.
Product data sheet Rev. 03 — 8 June 2009 19 of 24
NXP Semiconductors 74HC4538; 74HCT4538
Dual retriggerable precision monostable multivibrator
Fig 19. Package outline SOT109-1 (SO16)
X
wM
θ
A
A1
A2
bp
D
HE
Lp
Q
detail X
E
Z
e
c
L
vMA
(A )
3
A
8
9
1
16
y
pin 1 index
UNIT A
max. A1A2A3bpcD
(1) E(1) (1)
eH
ELL
pQZywv θ
REFERENCES
OUTLINE
VERSION EUROPEAN
PROJECTION ISSUE DATE
IEC JEDEC JEITA
mm
inches
1.75 0.25
0.10