Download PDF74HC423 PHILIPS
Document overview
- PDF pages: 14
Technical content
Page 1
INTEGRATED CIRCUITS
Page 2
FEATURES
- DC triggered from active HIGH or active LOW inputs
- Retriggerable for very long pulses up to 100% duty factor
- Direct reset terminates output pulse
- Schmitt-trigger action on all inputs except for the reset input
- Output capability: standard (except for nREXT/CEXT)
- ICC category: MSI
GENERAL DESCRIPTION
The 74HC/HCT423 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 74HC/HCT423 are dual retriggerable monostable multivibrators with output pulse width control by two methods. The basic pulse time is programmed by selection of an external resistor (REXT) and capacitor
QUICK REFERENCE DATA
GND = 0 V; Tamb = 25 °C; tr = tf = 6 ns
(CEXT). The external resistor and capacitor are normally connected as shown in Fig.6. Once triggered, the basic output pulse width may be extended by retriggering the gated active LOW-going edge input (nA) or the active HIGH-going edge input (nB). By repeating this process, the output pulse period (nQ = HIGH, nQ = LOW) can be made as long as desired. When nRD is LOW, it forces the nQ output LOW, the nQ output HIGH and also inhibits the triggering. Figures 7 and 8 illustrate pulse control by reset. The basic output pulse width is essentially determined by the values of the external timing components REXT and CEXT. For pulse widths, when CEXT < 10 000 pF, see Fig.9.
When CEXT > 10 000 pF, the typical output pulse width is defined as: tW = 0.45 × REXT × CEXT (typ.), where, tW = pulse width in ns; REXT = external resistor in kΩ; CEXT = external capacitor in pF. Schmitt-trigger action in the nA and nB inputs, makes the circuit highly tolerant to slower input rise and fall times. The “423” is identical to the “123” but cannot be triggered via the reset input.
| SYMBOL | PARAMETER | CONDITIONS | TYPICAL | UNIT | |
|---|---|---|---|---|---|
| HC | HCT | ||||
| t / t PHL PLH | propagation delay nA, nB to nQ, nQ nR to nQ, nQ D | C = 15 pF; V = 5 V; L CC R = 5 kΩ; C = 0 pF EXT EXT | 25 20 | 26 22 | ns ns |
| C I | input capacitance | 3.5 | 3.5 | pF | |
| t W | minimum output pulse width nQ, nQ | notes 1 and 2 | 75 | 75 | ns |
Notes 1. CPD is used to determine the dynamic power dissipation (PD in µW): PD = CPD × VCC2 × fi + ∑ (CL × VCC2 × fo) + 0.75 × CEXT × VCC2 × fo + D × 16 × VCC where: fi = input frequency in MHz fo = output frequency in MHz D = duty factor in % ∑ (CL × VCC2 × fo) = sum of outputs CL = output load capacitance in pF VCC = supply voltage in V CEXT = timing capacitance in pF 2. For HC the condition is VI = GND to VCC For HCT the condition is VI = GND to VCC − 1.5 V
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ORDERING INFORMATION
| TYPE NUMBER | PACKAGE | ||
|---|---|---|---|
| NAME | DESCRIPTION | VERSION | |
| 74HC423N; 74HCT423N | DIP16 | plastic dual in-line package; 16 leads (300 mil); long body | SOT38-1 |
| 74HC423D; 74HCT423D | SO16 | plastic small outline package; 16 leads; body width 3.9 mm; low stand-off height | SOT109-1 |
PIN DESCRIPTION
| PIN NO. | SYMBOL | NAME AND FUNCTION |
|---|---|---|
| 1, 9 2, 10 3, 11 4, 12 7 8 13, 5 14, 6 15 16 | 1A, 2A 1B, 2B 1R , 2R D D 1Q, 2Q 2R /C EXT EXT GND 1Q, 2Q 1C , 2C EXT EXT 1R /C EXT EXT V CC | trigger inputs (negative-edge triggered) trigger inputs (positive-edge triggered) direct reset action (active LOW) outputs (active LOW) external resistor/capacitor connection ground (0 V) outputs (active HIGH) external capacitor connection external resistor/capacitor connection positive supply voltage |
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74HC/HCT423
multivibrator with reset
FUNCTION TABLE
| Column 1 | Column 2 | Column 3 | Column 4 | Column 5 |
|---|---|---|---|---|
| INPUTS | OUTPUTS | |||
| nR D | nA | nB | nQ | nQ |
| L X X H H | X H X L ↓ | X X L ↑ H | L L(2) L(2) | H H(2) H(2) |
Notes 1. H = HIGH voltage level L = LOW voltage level X = don’t care ↑ = LOW-to-HIGH transition ↓ = HIGH-to-LOW transition
= one HIGH level output pulse
= one LOW level output pulse 2. If the monostable was triggered before this condition was established, the pulse will continue as programmed.
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74HC/HCT423
multivibrator with reset
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74HC/HCT423
multivibrator with reset
DC CHARACTERISTICS FOR 74HC
For the DC characteristics see “74HC/HCT/HCU/HCMOS Logic Family Specifications”. Output capability: standard (except for nREXT /CEXT) ICC category: MSI
AC CHARACTERISTICS FOR 74HC
GND = 0 V; tr = tf = 6 ns; CL = 50 pF
| SYMBOL | PARAMETER | T (°C) amb | UNIT | TEST CONDITIONS | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 74HC | V CC (V) | WAVEFORMS/ NOTES | |||||||||
| +25 | −40 to +85 | −40 to +125 | |||||||||
| min. | typ. | max | min | max | min. | max. | |||||
| t / t PHL PLH | propagation delay nA, nB to nQ, nQ | 80 29 23 | 255 51 43 | 320 64 54 | 385 77 65 | ns | 2.0 4.5 6.0 | C = 0 pF; EXT R = 5 kΩ EXT | |||
| t / t PHL PLH | propagation delay nR to nQ, nQ D | 66 24 19 | 215 43 37 | 270 54 46 | 325 65 55 | ns | 2.0 4.5 6.0 | C = 0 pF; EXT R = 5 kΩ EXT | |||
| t / t THL TLH | output transition time | 19 7 6 | 75 15 13 | 95 19 16 | 110 22 19 | ns | 2.0 4.5 6.0 | ||||
| t W | trigger pulse width nA = LOW | 100 20 17 | 11 4 3 | 125 25 21 | 150 30 26 | ns | 2.0 4.5 6.0 | Fig.7 | |||
| t W | trigger pulse width nB = HIGH | 100 20 17 | 17 6 5 | 125 25 21 | 150 30 26 | ns | 2.0 4.5 6.0 | Fig.7 | |||
| t W | reset pulse width nR = LOW D | 100 20 17 | 14 5 4 | 125 25 21 | 150 30 26 | ns | 2.0 4.5 6.0 | Fig.8 | |||
| t W | output pulse width nQ = HIGH nQ = LOW | 450 | − | − | µs | 5.0 | C = 100 nF; EXT R = 10 kΩ; EXT Figs 7 and 8 | ||||
| t W | output pulse width nQ = HIGH nQ = LOW | 75 | − | − | ns | 5.0 | C = 0 pF; EXT R = 5 kΩ; EXT note 1; Figs 7 and 8 | ||||
| t rt | retrigger time nA, nB | 110 | − | − | ns | 5.0 | C = 0 pF; EXT R = 5 kΩ; EXT note 2; Fig. 7 | ||||
| R EXT | external timing resistor | 10 2 | 1000 1000 | − | − | kΩ | 2.0 5.0 | Fig.9 | |||
| C EXT | external timing capacitor | no limits | pF | 5.0 | Fig.9; note 3 |
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74HC/HCT423
multivibrator with reset
DC CHARACTERISTICS FOR 74HCT
For the DC characteristics see “74HC/HCT/HCU/HCMOS Logic Family Specifications”. Output capability: standard (except for nREXT/CEXT) ICC category: MSI
Note to HCT types The value of additional quiescent supply current (∆ICC) for a unit load of 1 is given in the family specifications. To determine ∆ICC per input, multiply this value by the unit load coefficient shown in the table below.
| INPUT | UNIT LOAD COEFFICIENT |
|---|---|
| nA, nB nR D | 0.35 0.50 |
AC CHARACTERISTICS FOR 74HCT
GND = 0 V; tr = tf = 6 ns; CL = 50 pF
| SYMBOL | PARAMETER | T (°C) amb | UNIT | TEST CONDITIONS | |||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| 74HCT | V CC (V) | WAVEFORMS/ NOTES | |||||||||
| +25 | −40 to +85 | −40 to +125 | |||||||||
| min. | typ. | max. | min. | max. | min. | max. | |||||
| t / t PHL PLH | propagation delay nA, nB to nQ, nQ | 30 | 51 | 64 | 77 | ns | 4.5 | C = 0 pF; EXT R = 5 kΩ EXT | |||
| t / t PHL PLH | propagation delay nR to nQ, nQ D | 26 | 48 | 60 | 72 | ns | 4.5 | C = 0 pF; EXT R = 5 kΩ EXT | |||
| t / t THL TLH | output transition time | 7 | 15 | 19 | 22 | ns | 4.5 | ||||
| t W | trigger pulse width nA = LOW | 20 | 5 | 25 | 30 | ns | 4.5 | Fig.7 | |||
| t W | trigger pulse width nB = HIGH | 20 | 5 | 25 | 30 | ns | 4.5 | Fig.7 | |||
| t W | reset pulse width nR = LOW D | 20 | 7 | 25 | 30 | ns | 4.5 | Fig.8 | |||
| t W | output pulse width nQ = HIGH nQ = LOW | 450 | − | − | µs | 5.0 | C = 100 nF; EXT R = 10 kΩ; EXT Figs 7 and 8 | ||||
| t W | output pulse width nQ = HIGH nQ = LOW | 75 | − | − | ns | 5.0 | C = 0 pF; EXT R = 5 kΩ; EXT note 1; Figs 7 and 8 | ||||
| t rt | retrigger time nA, nB | 110 | − | − | ns | 5.0 | C = 0 pF; EXT R = 5 kΩ; EXT note 2; Fig.7 | ||||
| R EXT | external timing resistor | 2 | 1000 | − | − | kΩ | 5.0 | Fig.9 | |||
| C EXT | external timing capacitor | no limits | pF | 5.0 | Fig.9; note 3 |
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74HC/HCT423
multivibrator with reset
Notes 1. For other REXT and CEXT combinations see Fig.9. If CEXT > 10 pF, the next formula is valid: tW = K × REXT × CEXT (typ.) where: tW
= output pulse width in ns; REXT = external resistor in kΩ; CEXT = external capacitor in pF; = constant = 0.45 for VCC = 5.0 V and 0.55 for VCC = 2.0 V. K The inherent test jig and pin capacitance at pins 15 and 7 (nREXT/CEXT) is approximately 7 pF. 2. The time to retrigger the monostable multivibrator depends on the values of REXT and CEXT. The output pulse width will only be extended when the time between the active-going edges of the trigger input pulses meets the minimum retrigger time. If CEXT > 10 pF, the next formula (at VCC = 5.0 V) for the set-up time of a retrigger pulse is valid: trt = 30 + 0.19 × REXT × CEXT0.9 + 13 × REXT1.05 (typ.) where, trt
= retrigger time in ns; CEXT = external capacitor in pF; REXT = external resistor in kΩ. The inherent test jig and pin capacitance at pins 15 and 7 (nREXT/CEXT) is 7 pF. 3. When the device is powered-up, initiate the device via a reset pulse, when CEXT < 50 pF.
AC WAVEFORMS
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74HC/HCT423
multivibrator with reset
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74HC/HCT423
multivibrator with reset
APPLICATION INFORMATION
Power-up considerations When the monostable is powered-up it may produce an output pulse, with a pulse width defined by the values of RX and CX, this output pulse can be eliminated using the circuit shown in Fig.11.
Power-down considerations A large capacitor (CX) may cause problems when powering-down the monostable due to the energy stored in this capacitor. When a system containing this device is powered-down or a rapid decrease of VCC to zero occurs, the monostable may substain damage, due to the capacitor discharging through the input protection diodes. To avoid this possibility, use a damping diode (DX) preferably a germanium or Schottky-type diode able to withstand large current surges and connect as shown in Fig.12.
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74HC/HCT423
multivibrator with reset
PACKAGE OUTLINES
DIP16: plastic dual in-line package; 16 leads (300 mil); long body
SOT38-1
ME
D
A2 A
A1
L
c
e
w M
Z
b1
(e ) 1
b
MH
9
16
pin 1 index
E
1
8
0
5 10 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
| UNIT | A max. | A 1 min. | A 2 max. | b | b1 | c | D(1) | E(1) | e | e1 | L | ME | MH | w | Z(1) max. |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| mm | 4.7 | 0.51 | 3.7 | 1.40 1.14 | 0.53 0.38 | 0.32 0.23 | 21.8 21.4 | 6.48 6.20 | 2.54 | 7.62 | 3.9 3.4 | 8.25 7.80 | 9.5 8.3 | 0.254 | 2.2 |
| inches | 0.19 | 0.020 | 0.15 | 0.055 0.045 | 0.021 0.015 | 0.013 0.009 | 0.86 0.84 | 0.26 0.24 | 0.10 | 0.30 | 0.15 0.13 | 0.32 0.31 | 0.37 0.33 | 0.01 | 0.087 |
Note 1. Plastic or metal protrusions of 0.25 mm maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
ISSUE DATE
VERSION
PROJECTION
IEC
JEDEC
EIAJ
92-10-02
SOT38-1
050G09
MO-001AE
95-01-19
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74HC/HCT423
multivibrator with reset
SO16: plastic small outline package; 16 leads; body width 3.9 mm
SOT109-1
D
E
A X
c
y
HE
v M A
Z
16
9
Q
A2
A (A ) 3
A1
pin 1 index
θ Lp L
1
8
e
detail X
w M bp
0 2.5 5 mm
scale
DIMENSIONS (inch dimensions are derived from the original mm dimensions)
| UNIT | A max. | A1 | A2 | A3 | bp | c | D(1) | E(1) | e | HE | L | Lp | Q | v | w | y | Z(1) | θ |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| mm | 0 1.75 0 | .25 .10 | 1.45 1.25 | 0.25 | 0.49 0.36 | 0.25 0.19 | 10.0 9.8 | 4.0 3.8 | 1.27 | 6.2 5.8 | 1.05 | 1.0 0.4 | 0.7 0.6 | 0.25 | 0.25 | 0.1 | 0.7 0.3 | 8o 0o |
| inches | 0 0.069 0 | .010 .004 | 0.057 0.049 | 0.01 | 0.019 0.014 | 0.0100 0.0075 | 0.39 0.38 | 0.16 0.15 | 0.050 | 0.244 0.228 | 0.041 | 0.039 0.016 | 0.028 0.020 | 0.01 | 0.01 | 0.004 | 0.028 0.012 |
Note 1. Plastic or metal protrusions of 0.15 mm maximum per side are not included.
REFERENCES
OUTLINE
EUROPEAN
ISSUE DATE
VERSION
PROJECTION
IEC
JEDEC
EIAJ
95-01-23
076E07S
MS-012AC
SOT109-1
97-05-22
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SOLDERING
Introduction There is no soldering method that is ideal for all IC packages. Wave soldering is often preferred when through-hole and surface mounted components are mixed on one printed-circuit board. However, wave soldering is not always suitable for surface mounted ICs, or for printed-circuits with high population densities. In these situations reflow soldering is often used. This text gives a very brief insight to a complex technology. A more in-depth account of soldering ICs can be found in our “Data Handbook IC26; Integrated Circuit Packages” (order code 9398 652 90011).
DIP SOLDERING BY DIPPING OR BY WAVE The maximum permissible temperature of the solder is 260 °C; solder at this temperature must not be in contact with the joint for more than 5 seconds. The total contact time of successive solder waves must not exceed 5 seconds. The device may be mounted up to the seating plane, but the temperature of the plastic body must not exceed the specified maximum storage temperature (Tstg max). If the printed-circuit board has been pre-heated, forced cooling may be necessary immediately after soldering to keep the temperature within the permissible limit.
REPAIRING SOLDERED JOINTS Apply a low voltage soldering iron (less than 24 V) to the lead(s) of the package, below the seating plane or not more than 2 mm above it. If the temperature of the soldering iron bit is less than 300 °C it may remain in contact for up to 10 seconds. If the bit temperature is between 300 and 400 °C, contact may be up to 5 seconds.
SO REFLOW SOLDERING Reflow soldering techniques are suitable for all SO packages. Reflow soldering requires solder paste (a suspension of fine solder particles, flux and binding agent) to be applied to the printed-circuit board by screen printing, stencilling or pressure-syringe dispensing before package placement.
Several techniques exist for reflowing; for example, thermal conduction by heated belt. Dwell times vary between 50 and 300 seconds depending on heating method. Typical reflow temperatures range from 215 to 250 °C. Preheating is necessary to dry the paste and evaporate the binding agent. Preheating duration: 45 minutes at 45 °C.
WAVE SOLDERING Wave soldering techniques can be used for all SO packages if the following conditions are observed:
- A double-wave (a turbulent wave with high upward pressure followed by a smooth laminar wave) soldering technique should be used.
- The longitudinal axis of the package footprint must be parallel to the solder flow.
- The package footprint must incorporate solder thieves at the downstream end.
During placement and before soldering, the package must be fixed with a droplet of adhesive. The adhesive can be applied by screen printing, pin transfer or syringe dispensing. The package can be soldered after the adhesive is cured. Maximum permissible solder temperature is 260 °C, and maximum duration of package immersion in solder is 10 seconds, if cooled to less than 150 °C within 6 seconds. Typical dwell time is 4 seconds at 250 °C. A mildly-activated flux will eliminate the need for removal of corrosive residues in most applications.
REPAIRING SOLDERED JOINTS Fix the component by first soldering two diagonallyopposite end leads. Use only a low voltage soldering iron (less than 24 V) applied to the flat part of the lead. Contact time must be limited to 10 seconds at up to 300 °C. When using a dedicated tool, all other leads can be soldered in one operation within 2 to 5 seconds between 270 and 320 °C.
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74HC/HCT423
multivibrator with reset
DEFINITIONS
| Column 1 | Column 2 |
|---|---|
| Data sheet status | |
| Objective specification | This data sheet contains target or goal specifications for product development. |
| Preliminary specification | This data sheet contains preliminary data; supplementary data may be published later. |
| Product specification | This data sheet contains final product specifications. |
| Limiting values | |
| Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended periods may affect device reliability. | |
| Application information | |
| Where application information is given, it is advisory and does not form part of the specification. |
LIFE SUPPORT APPLICATIONS
These products are not designed for use in life support appliances, devices, or systems where malfunction of these products can reasonably be expected to result in personal injury. Philips customers using or selling these products for use in such applications do so at their own risk and agree to fully indemnify Philips for any damages resulting from such improper use or sale.