MC1455DG - Single 555 Timer, 16V, 8-SOIC | onsemi
MPN： MC1455DG ✓ 啟用中MC1455DG 概覽
A 555 timer is an analog timing integrated circuit that combines a voltage comparator, a flip-flop, discharge transistor, and resistive divider into one reusable building block. Within the broader hierarchy, it is a clock and timing IC within integrated circuits, providing a simple alternative to a dedicated programmable timer or microcontroller-based timing solution. The MC1455 can operate as a monostable one-shot, as an astable oscillator, or as a Schmitt-trigger comparator.
The MC1455DG provides a single timer in an 8-SOIC package, operates from 4.5 V to 16 V, and is specified for a 0°C to 70°C temperature range. In monostable mode, one external resistor and one capacitor control the output pulse duration. In astable mode, two resistors and one capacitor establish the oscillation frequency and duty cycle, while the control, trigger, reset, threshold, and discharge pins support the standard 555 application topology.
Timing accuracy depends on the external resistor and capacitor tolerances, the device's internal reference behavior, and the operating voltage. Because the trigger input is compared against one-third of the supply voltage and the threshold input is compared against two-thirds of the supply voltage, the timing network sees supply-dependent reference levels. Designers should therefore use stable precision components and avoid high-impedance timing nodes where practical.
Typical uses include industrial control pulse generation, relay activation delays, debounce timers, low-frequency oscillators, sensor timeout circuits, and audio-envelope generators. It is also useful in educational and evaluation boards where a simple external-resistor-and-capacitor timing method is preferable to firmware-based timing.
For robust layouts, connect the control bypass capacitor close to the control pin, keep the timing capacitor's ground return short, and route the discharge transistor output away from sensitive analog signals. Confirm trigger and reset levels in the selected operating mode because a floating control, trigger, or reset node can produce unintended output transitions.
This page combines verified manufacturer and distributor information with pin-level guidance, application fit, comparison parameters, and replacement considerations. It also documents where full electrical limits, qualified pricing, and lifecycle-specific details remain unavailable in the supplied source data.
直接替換替代品，適用於 MC1455DG — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
此系列的變體
與下列產品可直接替換的同系列型號： MC1455DG （相同外形與佔位） — 差異在於 Operating Modes, Package.
MC1455DR2G
✅ 直接替換📋 參考替代品（不在目錄中）
NE555DG4
✅ 直接替換📋 參考替代品（不在目錄中）
SA555D
✅ 直接替換📋 參考替代品（不在目錄中）
ICM7555CBAZ
✅ 直接替換📋 參考替代品（不在目錄中）
MC1455DG 規格
| Product Type | General-purpose timer / oscillator integrated circuit |
| Timer Count | 1 timer per package |
| Timer Family | 555 type |
| Supply Voltage Range | 4.5 V to 16 V |
| Maximum Supply Voltage | 16 V |
| Operating Modes | Monostable, astable, and Schmitt-trigger |
| External Timing Components | 1 resistor and 1 capacitor in monostable mode; 2 resistors and 1 capacitor in astable mode |
| 輸出類型 | Single timer output |
| Control Functions | Trigger and reset terminals |
| 封裝 | 8-SOIC, 0.154 inch pitch |
| 腳位數 | 8 pins |
| 安裝類型 | Surface mount |
| 工作溫度範圍 | 0°C to 70°C |
MC1455DG 腳位配置
| 腳位 1 | GND — Ground reference |
| 腳位 2 | TRIGGER — Low-voltage trigger input for the internal flip-flop |
| 腳位 3 | OUTPUT — Timer output |
| 腳位 4 | RESET — Active-low reset input |
| 腳位 5 | CONTROL VOLTAGE — Internal threshold-reference control input |
| 腳位 6 | THRESHOLD — Timing-capacitor threshold-sense input |
| 腳位 7 | DISCHARGE — Open-collector discharge transistor output |
| 腳位 8 | VCC — Positive supply input |
典型應用
MC1455DG 適用於 6 應用s: Industrial Pulse and Delay Generation, Low-Frequency Astable Oscillator, Relay Actuation Timeout, Sensor Debounce and Timeout, Audio Envelope and Tone Generation, Evaluation and Educational Timer Circuits.
Industrial Pulse and Delay Generation
The MC1455DG fits industrial pulse-generation circuits because one external resistor and one capacitor establish a monostable delay while the trigger and reset pins provide deterministic control. Its 4.5 V to 16 V operating range supports common control rails, and the single 8-SOIC package simplifies dense controller boards. Place the timing capacitor near the threshold pin, add a local bypass capacitor at VCC, and keep the discharge trace away from sensitive analog nodes. The main trade-off is that timing accuracy depends on the external R-C network and ambient temperature within the verified 0°C to 70°C range.
推薦
Low-Frequency Astable Oscillator
The MC1455DG can free-run as an astable oscillator using two resistors and one capacitor, providing a simple clock for blinking indicators, sampling sequences, or repetitive control pulses. Its trigger, threshold, and discharge architecture implements the conventional 555 oscillator without requiring a microcontroller or a dedicated clock IC. The calculated frequency should be checked against resistor and capacitor tolerances, and the supply should remain stable because the internal threshold references are proportional to VCC. For very low power systems, compare this approach with a CMOS timer whose quiescent current may be lower.
推薦
Relay Actuation Timeout
In relay-control circuits, the MC1455DG provides a hardware-defined delay between a trigger event and an actuator output, reducing dependence on firmware timing. The output can energize a relay driver during the monostable interval, while the trigger and reset inputs allow the sequence to be initiated or canceled. Its 4.5 V to 16 V supply range is suitable for regulated 5 V or 12 V control systems. Designers must add suitable transistor drive and flyback protection, verify relay coil current against the timer output's verified limits, and keep the high-voltage switching node isolated from the timing network.
推薦
Sensor Debounce and Timeout
The MC1455DG can debounce a mechanical switch or implement a sensor-event timeout because its Schmitt-trigger action requires the threshold input to cross a defined internal reference before the output changes. This hardware filtering prevents a bouncing contact from appearing as multiple valid events to downstream logic. The 8-SOIC package is convenient for mixed-signal controller boards, and the single timer supports the common 555 pinout. Keep the switch input shielded from noise, provide a defined reset state, and select R-C values that exceed the expected bounce duration without making the response unnecessarily slow.
推薦
Audio Envelope and Tone Generation
The MC1455DG can generate a repeating tone or simple amplitude-envelope trigger for low-cost audio and evaluation circuits by operating as an astable oscillator with external timing components. Its conventional 555 architecture is easy to prototype on a breadboard and does not require an embedded oscillator or DAC. Keep the timing capacitor physically close to the device and route the output through an AC-coupling stage so the DC component does not disturb downstream audio biasing. For low-noise hi-fi reproduction, verify the output-noise spectrum and consider a dedicated audio oscillator because the MC1455DG is primarily a general-purpose timing device.
推薦
Evaluation and Educational Timer Circuits
The MC1455DG is well suited to education and evaluation boards because its monostable and astable functions can be demonstrated with only external resistors, capacitors, and standard test equipment. Students can visualize how trigger, threshold, discharge, and output interact across a timing cycle while learning the relationship between R-C values and pulse duration. The 8-SOIC package requires careful soldering and inspection, so a socketed demonstration board is preferable for training use. Add labeled test points for supply, output, threshold, and timing capacitor voltage, and use current limiting when students probe the circuit.
推薦
推薦產品摘要
工程參考資料，適用於 MC1455DG — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | MC1455DR2G | NE555DG4 | SA555D | ICM7555CBAZ | NE555DR |
|---|---|---|---|---|---|---|
| Package | 8-SOIC | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same | 8-SOIC - same |
| Brand | onsemi | onsemi | Texas Instruments | Texas Instruments | Renesas Electronics | Texas Instruments |
| Timer Type | Single 555 type | Single 555 type | Single 555 type | Single precision timer | Single CMOS timer | Single 555 type |
| Operating Modes | Monostable, astable, and Schmitt-trigger | Monostable and astable timer functions | Monostable and astable timer functions | Monostable and astable timer functions | Monostable and astable timer functions | Monostable and astable timer functions |
| Trigger and Reset Control | Yes | Yes | Yes | Yes | Yes | Yes |
| Timing Network | 1 R-C network in monostable mode; 2 resistors and 1 capacitor in astable mode | External R-C timing network | External R-C timing network | External R-C timing network | External R-C timing network | External R-C timing network |
主要差異化特點
- Same-manufacturer MC1455-family replacement path (對比MC1455DR2G)
- Broader supply compatibility than the listed CMOS alternative (對比ICM7555CBAZ)
- Onsemi procurement continuity for existing MC1455 designs (對比NE555DG4)
- Single dedicated timer rather than a dual-timer alternative (對比MC1455DR2G)
設計說明
Route the timing capacitor directly to the threshold pin, connect the timing resistor to the discharge network with minimal loop area, and bypass VCC near pin 8. The discharge output at pin 7 can create fast current edges, so keep that trace away from high-impedance trigger and threshold wiring. Use a common ground return that does not force timing current through the same path as an actuator or relay-load return.
The MC1455DG operates from 4.5 V to 16 V according to the verified source data. Treat the 16 V value as an upper operating boundary and include supply transient margin for the actual circuit. Do not infer output-current capability from generic 555-family data; consult the manufacturer datasheet for sink and source limits before driving relays, LEDs, or other loads directly. Add transistor or MOSFET drive where the load current exceeds the verified device rating.
A floating trigger, reset, or control-voltage pin can cause unintended timer transitions. The control-voltage pin normally requires a bypass capacitor, while trigger and reset should be driven to defined logic levels or held by a suitable resistor network. Timing accuracy also depends on R-C component tolerance and temperature. Avoid replacing precision timing resistors with arbitrary values, and verify the trigger level against the actual supply rather than assuming a 5 V logic threshold.
In astable mode, the threshold and trigger nodes carry slow-moving capacitor voltages, but the discharge node switches quickly. Keep sensitive analog inputs away from pin 7 and avoid using long PCB runs for the timing network. If the timer drives a cable, long trace, or relay coil, isolate the load with a driver stage so board loading does not disturb the discharge transistor or timing waveform.
合規資訊
The supplied verified results identify the manufacturer, package, supply range, temperature range, and application information but do not explicitly state RoHS, REACH, halogen-free, or conflict-minerals status. AEC-Q100 is not applicable because the listed MC1455DG is a 0°C to 70°C commercial-temperature part, not an identified automotive-qualified variant.
