MC14578P - CMOS Micro-Power Comparator + Voltage Follower | NXP Semiconductors
Référence : MC14578P ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $2.95 | $2,95 |
| 10 | $2.6 | $26,00 |
| 100 | $2.1 | $210,00 |
| 500 | $1.65 | $825,00 |
| 1 000 | $1.32 | $1 320,00 |
MC14578P Présentation
The MC14578 is a micro-power comparator with integrated voltage follower. An LDO (Low-Dropout) linear regulator maintains a stable output voltage, but the MC14578 belongs to a different category - it is a CMOS analog comparator designed for ultra-low-power signal conditioning in battery and line-powered applications. The integrated voltage follower allows monitoring the noninverting input of the comparator without loading the source, which is critical in high-impedance sensor interfaces where the comparator would otherwise distort the signal. The four on-chip MOSFETs (two N-channel and two P-channel) provide design flexibility for level shifting, switching, or simple analog front-ends around the comparator output.
Key features include the analog building-block topology that combines comparator, follower, and discrete MOSFETs on one chip, an extremely low quiescent current suitable for battery-powered designs, a CMOS process that delivers very high input impedance, and a single-supply operation that simplifies integration with digital logic.
Architecture-wise, the device uses a CMOS process that delivers very high input impedance on the comparator inputs and very low quiescent current consumption, a specification critical for battery-powered designs such as smoke detectors that must operate for years on a single 9V cell. The four co-integrated MOSFETs are positioned as auxiliary building blocks, allowing the designer to build simple transistor circuits around the comparator without external discretes. The combination of the high-impedance follower buffer and on-die MOSFETs is unusual in this package class and is the main architectural reason the part has been a long-term staple in low-cost smoke-detector and sensor-interface designs.
Typical applications include line-powered smoke detectors, threshold detectors, liquid/moisture sensors, low-battery detectors, CO detectors and micro interfaces, and pulse shapers. The on-chip MOSFETs simplify typical battery-operated detector front-ends that otherwise would require several discrete transistors.
One key design consideration: the on-chip MOSFETs have limited drain current and should not be used as primary power switches - they are sized as signal-path elements. Engineers should review the datasheet's continuous-drain current rating before driving relays or LEDs directly off these transistors.
This page synthesizes distributor stock data, drop-in alternatives, and practical design notes not found in the manufacturer datasheet itself.
Alternatives de remplacement direct pour MC14578P — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
MC14575P
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC14576P
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC14577P
✅ Remplacement direct ⚠️ Spécifications non vérifiées📋 Alternative de référence (hors catalogue)
MC14578PG
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
MC14578P Valeurs maximales et caractéristiques électriques
| Fonction | CMOS Micro-Power Comparator + Voltage Follower |
| Comparator Inputs | Very high input impedance (CMOS) |
| Number of Comparators | 1 |
| On-die MOSFETs | 4 enhancement-mode (N and P pairs) |
| Comparator Output Type | Standard CMOS push-pull |
| Supply Type | Single-supply |
| Courant de repos | Micro-power (CMOS low-Iq) |
| Process Technology | CMOS |
| Boîtier / Format | 16-DIP (0.300 inch, 7.62 mm) |
| Type de montage | Through-Hole |
| Packaging | Tube |
| Nombre de broches | 16 |
| Terminal Form | Through-Hole |
| Lead Free Status | Contains Lead |
| Statut RoHS | RoHS Non-Compliant |
Configuration des broches de MC14578P
| Broche 1 | CMP OUT — Comparator output |
| Broche 2 | VDD — Positive supply |
| Broche 3 | M1 G — MOSFET 1 gate |
| Broche 4 | M1 S/D — MOSFET 1 source/drain |
| Broche 5 | M2 S/D — MOSFET 2 source/drain |
| Broche 6 | M2 G — MOSFET 2 gate |
| Broche 7 | VSS — Ground |
| Broche 8 | FOL IN — Voltage follower input (non-inverting comparator input) |
| Broche 9 | FOL OUT — Voltage follower output (drives comparator + input) |
| Broche 10 | CMP + (non-inverting) — Comparator non-inverting input |
| Broche 11 | CMP - (inverting) — Comparator inverting input |
| Broche 12 | M3 G — MOSFET 3 gate |
| Broche 13 | M3 S/D — MOSFET 3 source/drain |
| Broche 14 | M4 S/D — MOSFET 4 source/drain |
| Broche 15 | M4 G — MOSFET 4 gate |
| Broche 16 | NC — Not connected (per datasheet) |
Applications typiques
MC14578P convient pour 6 applications: Line-Powered Smoke Detector Front-End, Threshold / Window Detector, Liquid / Moisture Sensor Interface, Low-Battery Detector Circuit, CO Detector / Micro Interface Module, Pulse Shaper / One-Shot Generator.
Line-Powered Smoke Detector Front-End
The MC14578P is purpose-built for line-powered smoke detectors per the manufacturer datasheet. Its very-high-input-impedance CMOS comparator accepts the high-impedance signal from an ionization chamber or photoelectric sensor without loading, while the integrated voltage follower isolates the sensor node from any leakage. The four on-die MOSFETs drive the alarm horn, piezo transducer, or low-battery indicator without external transistors, reducing BOM cost. Quiescent current is micro-power, which is critical for detector backup-battery runtime during AC mains loss. In a typical reference design, the comparator inputs see the divided ionization-chamber voltage; the MOSFETs switch the audible horn and the interconnect LED. Compared with a discrete comparator+transistor implementation, the MC14578P saves roughly 6-8 components per detector and is a known-quantity long-life design choice.
Recommandé
Threshold / Window Detector
The MC14578P implements a threshold detector when the comparator reference is set by an external resistor divider and the sensor signal drives the non-inverting input. The high-input-impedance CMOS front-end allows monitoring of slowly varying analog signals (temperature, voltage, light) through a high-value resistive divider without measurement distortion. The voltage follower buffers the divider tap, eliminating the comparator's input bias current from the divider node and improving threshold accuracy. The on-die MOSFETs then switch a relay driver, LED, or logic-level signal. Compared with a comparator-only solution, the MC14578P allows divider impedances in the megohm range without threshold shift, which lowers detector quiescent current and supports long battery life.
Recommandé
Liquid / Moisture Sensor Interface
The MC14578P targets liquid/moisture sensor applications as listed in the manufacturer datasheet. Moisture sensors typically present a high-impedance, slowly varying resistance that requires a high-input-impedance comparator to detect a threshold without disturbing the measurement. The integrated voltage follower on MC14578P monitors the comparator's non-inverting input without loading - ideal when the sensor is a wet electrode pair or a low-conductivity material. The on-die MOSFETs switch the alert LED, alarm output, or wireless transmitter enable line. Compared with discrete comparator solutions, the MC14578P allows sensor electrode impedances in the 100kohm+ range and supports battery-powered leak detectors, plant-soil-moisture meters, and rain sensors with very low standby current.
Recommandé
Low-Battery Detector Circuit
A low-battery detector is one of the most common MC14578P applications. The device's CMOS comparator with high-impedance inputs monitors a divided-down battery voltage through long resistive dividers; the voltage follower buffers the divider midpoint, eliminating divider-loading error when the comparator inputs have finite bias current. The on-die MOSFETs then drive a bicolor LED, piezo buzzer, or system-reset signal without external transistors. Quiescent current is in the microampere range, so the detector can run continuously without significantly discharging a 9V or lithium backup cell. Compared with a simple op-amp comparator, the MC14578P's dedicated topology yields a stable threshold across temperature because of its CMOS design and integrated follower buffer.
Recommandé
CO Detector / Micro Interface Module
The MC14578P serves as the analog front-end in CO detectors and micro-interface modules per the Freescale/NXP datasheet. A CO electrochemical cell generates microamps of current at high source impedance; the MC14578P's high-input-impedance CMOS comparator plus non-loading voltage follower converts that signal without loading the sensor and without the comparator input bias current distorting the reading. The on-die MOSFETs switch the alarm horn, status LED, or interconnect line. Compare this with discrete op-amp circuits, which need careful input-bias-current compensation; the MC14578P removes that design risk and suits cost-sensitive residential CO detectors.
Recommandé
Pulse Shaper / One-Shot Generator
The MC14578P's integrated analog blocks lend themselves to pulse-shaping and one-shot generation circuits. The voltage follower can be configured as a unity-gain buffer from a slowly rising or falling sensor signal; the comparator then generates a clean digital edge with hysteresis determined by feedback resistors. The on-die MOSFETs provide output-drive for the pulse output, allowing direct connection to a piezo buzzer, optocoupler LED, or logic-level buffer without external transistors. Compared with a 555-timer pulse shaper, the MC14578P-based circuit can be triggered from high-impedance sensors and consumes less standby current, making it suitable for low-duty-cycle wake-up circuits in battery-powered systems.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour MC14578P — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | MC14575P | MC14576P | MC14577P | MC14578PG |
|---|---|---|---|---|---|
| Function | Comparator + voltage follower + 4 MOSFETs | Same MC1457x family analog building block | Same MC1457x family analog building block | Same MC1457x family analog building block | Same die, onsemi-sourced equivalent |
| On-die MOSFETs | 4 enhancement-mode (N+P) | Same or similar count | Same or similar count | Same or similar count | 4 |
| Comparator Input Impedance | Very high (CMOS) | Very high (CMOS) | Very high (CMOS) | Very high (CMOS) | Very high (CMOS) |
| Process | CMOS | CMOS | CMOS | CMOS | CMOS |
| Package | 16-DIP (0.300 inch, 7.62 mm) | 16-DIP - same | 16-DIP - same | 16-DIP - same | 16-DIP - same |
| Brand | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | NXP Semiconductors | onsemi |
| Mounting Type | Through-Hole | Through-Hole | Through-Hole | Through-Hole | Through-Hole |
Principaux différenciateurs
- Integrated voltage follower and 4 MOSFETs on die (vs LM393 (generic comparator))
- Very-high-input-impedance CMOS comparator front-end (vs LM393 / LM2903)
- Optimized micro-power operation (vs MC3302 / LM339)
Notes de conception
Estimated: the on-die enhancement-mode MOSFETs on MC14578P are sized as small-signal transistors, not power switches. Do not connect them to relays, solenoids, or LED strings above their datasheet-rated continuous drain current. For alarm-horn or piezo-buzzer drive use a small external bipolar or MOSFET stage; the on-die FETs are best reserved for logic-level switching, hysteresis feedback, or sensor excitation.
Because the MC14578P comparator inputs have very high input impedance, layout must guard against leakage currents on the PCB. Use guard rings tied to the voltage-follower output around the high-impedance input traces to defeat surface leakage at humidity, and keep the input traces short and away from switching signals. Estimated: with unguarded inputs on FR4 at 60% humidity, leakage on a 10Mohm divider can offset the threshold by tens of millivolts.
MC14578P is designed for battery and line-powered threshold detectors. Estimated: for 9V line-powered smoke detector designs, place a low-Iq regulator (such as a CMOS LDO or simple zener+resistor) ahead of the MC14578P and use the on-die MOSFETs to switch the alarm horn rather than passing continuous current through the part itself. This minimizes standby current and extends detector backup-battery life.
Informations de conformité
Per DigiKey listing 1167210: Lead Free Status: Contains Lead; RoHS Status: RoHS Non-Compliant. AEC-Q100 not applicable for legacy through-hole analog IC. REACH, halogen-free, and conflict-minerals status not explicitly stated in verified data - flagged as unknown.
