Overview
The MC34067P, produced by onsemi, is a high-performance bipolar integrated circuit (IC) designed for variable frequency power control in resonant mode applications. This IC is specifically tailored for zero voltage switching (ZVS) quasi-resonant converter (QRC) applications, particularly in off-line and DC-to-DC converter systems. It features a variable frequency oscillator, a precise retriggerable one-shot timer, and a high-gain wide-bandwidth error amplifier, making it ideal for driving power MOSFETs in high-frequency applications.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Reference Output Voltage | Vref | 5.0 | 5.1 | 5.2 | V |
| Line Regulation | Regline | -1.0 | - | 20 | mV |
| Load Regulation | Regload | -1.0 | - | 20 | mV |
| Total Output Variation Over Line, Load, and Temperature | Vref | 4.9 | - | 5.3 | V |
| Output Short Circuit Current | IO | 30 | 25 | 100 | mA |
| Reference Undervoltage Lockout Threshold | Vth | 3.8 | 4.3 | 4.8 | V |
| Error Amplifier Input Offset Voltage | VIO | -1.0 | - | 10 | mV |
| Error Amplifier Input Bias Current | IIB | -0.2 | - | 1.0 | μA |
| Error Amplifier Open Loop Voltage Gain | AVOL | 70 | 100 | - | dB |
| Output Voltage Swing (High State) | VOH | 2.8 | - | 3.2 | V |
| Output Voltage Swing (Low State) | VOL | 0.6 | - | 0.8 | V |
| Operating Junction Temperature | TJ | - | - | 150 | °C |
| Operating Ambient Temperature | TA | 0 | - | 70 | °C |
| Storage Temperature | Tstg | -55 | - | 150 | °C |
Key Features
- Zero Voltage Switch Resonant Mode Operation: Optimized for zero voltage switching quasi-resonant converter applications.
- Variable Frequency Oscillator: Control range exceeding 1000:1, allowing for precise frequency modulation.
- Precision One-Shot Timer: Provides controlled off-time for the power MOSFETs.
- Internally Trimmed Bandgap Reference: Offers stable reference voltage.
- High Gain Wide Bandwidth Error Amplifier: Monitors the output and modulates the oscillator frequency.
- Dual High Current Totem Pole Outputs: Capable of sourcing and sinking 1.5 A, ideal for driving power MOSFETs.
- Selectable Undervoltage Lockout Thresholds with Hysteresis: Ensures safe startup and shutdown.
- Programmable Soft-Start Circuitry: Reduces inrush current during startup.
- Fault Detector and Latch: Quickly disables the system in case of a fault condition.
- Low Startup Current for Off-Line Operation: Suitable for off-line applications.
- AEC-Q100 Qualified and PPAP Capable: Meets automotive and other stringent application requirements.
- Pb-Free, Halogen Free/BFR Free and RoHS Compliant: Environmentally friendly packaging.
Applications
The MC34067P is specifically designed for zero voltage switching (ZVS) quasi-resonant converter (QRC) applications, particularly in:
- Off-Line and DC-to-DC Converters: Ideal for high-frequency power conversion.
- Double-Ended Push-Pull or Bridge Type Converters: Optimized for continuous conduction mode.
- Automotive and Industrial Power Supplies: Meets the stringent requirements of automotive and industrial applications.
Q & A
- What is the primary function of the MC34067P?
The primary function of the MC34067P is to provide a fixed off-time to the gates of external power MOSFETs at a repetition rate regulated by a feedback control loop in zero voltage switching resonant mode applications.
- What is the frequency range of the variable frequency oscillator?
The variable frequency oscillator has a control range exceeding 1000:1, allowing for precise frequency modulation at frequencies exceeding 1.0 MHz.
- What are the key features of the error amplifier?
The error amplifier has a high gain, wide bandwidth, and monitors the output to modulate the oscillator frequency. It also has an open-loop voltage gain of 70 to 100 dB.
- How does the undervoltage lockout (UVLO) work?
The UVLO has separate comparators for input VCC voltage and the regulated reference voltage. It ensures safe startup and shutdown by enabling or disabling the controller based on the voltage thresholds.
- What is the purpose of the soft-start circuitry?
The soft-start circuitry reduces inrush current during startup, ensuring a controlled and safe power-up sequence.
- What are the output capabilities of the totem pole drivers?
The totem pole drivers are capable of sourcing and sinking 1.5 A, with rise and fall times typically 20 ns and 15 ns, respectively, when driving a 1.0 nF load.
- How does the fault detector and latch function?
The fault detector and latch quickly disable the system in case of a fault condition. The fault latch can be reset during startup or by momentarily pulling the Enable/UVLO Adjust pin low.
- Is the MC34067P suitable for automotive applications?
Yes, the MC34067P is AEC-Q100 qualified and PPAP capable, making it suitable for automotive and other stringent application requirements.
- What are the environmental compliance features of the MC34067P?
The MC34067P is Pb-Free, Halogen Free/BFR Free, and RoHS compliant, ensuring environmentally friendly packaging.
- What is the operating temperature range of the MC34067P?
The operating ambient temperature range is 0°C to 70°C, and the storage temperature range is -55°C to 150°C.
