Overview
The MC33368 is an active power factor correction controller designed by ON Semiconductor, functioning as a boost preconverter in off-line power supply applications. It is optimized for low power, high density power supplies, requiring a minimum board area, reduced component count, and low power dissipation. The device features a narrow body SOIC package, providing a small footprint. The integration of high voltage startup saves approximately 0.7 W of power compared to resistor bootstrapped circuits.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Power Supply Voltage (Transient) | VCC | 20 | V | ||
| Maximum Power Dissipation @ TA = 70°C | PD | 450 | mW | ||
| Thermal Resistance, Junction-to-Air | RJA | 178 | °C/W | ||
| Operating Junction Temperature | TJ | 150 | °C | ||
| Operating Ambient Temperature | TA | -25 | 125 | °C | |
| Input Bias Current (VFB = 5.0 V) | IIB | 0 | 1.0 | μA | |
| Input Offset Voltage (VComp = 3.0 V) | VIO | -2.0 | 50 | mV | |
| Transconductance (VComp = 3.0 V) | gm | 30 | 51 | 80 | μmho |
| Watchdog Timer Delay | tDLY | 180 | 385 | 800 | μs |
| Restart Timer Threshold | Vth(restart) | 1.5 | 2.3 | 3.0 | V |
Key Features
- Active Power Factor Control
- Lossless Off-Line Startup
- Output Overvoltage Comparator
- Leading Edge Blanking (LEB) for Noise Immunity
- Watchdog Timer to Initiate Switching
- Restart Delay Timer
- One Quadrant Multiplier to force the line current to follow the instantaneous line voltage
- Zero Current Detector for critical conduction operation
- Transconductance Error Amplifier
- Current Sensing Comparator
- 5.0 V Reference
- Undervoltage Lockout (UVLO) Circuit
- CMOS Driver for driving MOSFETs
- Programmable Output Switching Frequency Clamp
- Cycle-by-Cycle Current Limiting
Applications
The MC33368 is designed for use in off-line power supply applications, particularly in scenarios requiring high power factor correction and efficient power management. It is suitable for low power, high density power supplies where minimizing board area and component count is crucial.
- Off-Line Power Supplies
- Boost Preconverter Applications
- High Density Power Supplies
Q & A
- What is the primary function of the MC33368?
The MC33368 is an active power factor correction controller that functions as a boost preconverter in off-line power supply applications.
- What are the key benefits of the MC33368's high voltage startup?
The high voltage startup saves approximately 0.7 W of power compared to resistor bootstrapped circuits.
- What protection features does the MC33368 include?
The MC33368 includes an output overvoltage comparator, a restart delay timer, and cycle-by-cycle current limiting.
- What is the purpose of the watchdog timer in the MC33368?
The watchdog timer initiates output switching and ensures proper operation of the device.
- What is the operating junction temperature range of the MC33368?
The operating junction temperature range is from -25°C to 150°C.
- What is the maximum power dissipation of the MC33368 at TA = 70°C?
The maximum power dissipation is 450 mW.
- What type of package does the MC33368 come in?
The MC33368 comes in a narrow body SOIC-16 package.
- What is the role of the one quadrant multiplier in the MC33368?
The one quadrant multiplier forces the line current to follow the instantaneous line voltage.
- Does the MC33368 include a CMOS driver?
Yes, the MC33368 includes a CMOS driver for driving MOSFETs.
- What is the typical transconductance of the error amplifier in the MC33368?
The typical transconductance is 51 μmho.
- What is the restart timer threshold voltage range for the MC33368?
The restart timer threshold voltage range is from 1.5 V to 3.0 V.
