Overview
The MC34025DWG, produced by onsemi, is a high-speed, fixed-frequency, double-ended pulse width modulator (PWM) controller. This integrated circuit is optimized for high-frequency operation and is specifically designed for off-line and DC-to-DC converter applications. It offers a cost-effective solution with minimal external components, making it ideal for designers seeking efficient and reliable power supply control.
The MC34025 series features an oscillator, a temperature-compensated reference, a wide bandwidth error amplifier, a high-speed current sensing comparator, a steering flip-flop, and dual high current totem pole outputs. These outputs are designed to drive power MOSFETs directly. The IC also includes protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Power Supply Voltage | VCC | - | - | 30 | V |
| Output Driver Supply Voltage | VC | - | - | 25 | V |
| Output Current, Source or Sink | IO | - | - | 2.0 | A |
| Reference Output Voltage | Vref | 5.05 | 5.1 | 5.15 | V |
| Input Offset Voltage | VIO | - | - | 15 | mV |
| Propagation Delay (Current Limit/Shutdown to Output) | tPLH(in/out) | - | 50 | 80 | ns |
| Operating Junction Temperature | TJ | - | - | 150 | °C |
| Operating Ambient Temperature | TA | 0 | - | 70 | °C |
Key Features
- 50 ns Propagation Delay to Outputs
- Dual High Current Totem Pole Outputs, capable of up to ±2.0 A peak drive current
- Wide Bandwidth Error Amplifier
- Fully-Latched Logic with Double Pulse Suppression
- Latching PWM for Cycle-By-Cycle Current Limiting
- Temperature-Compensated Reference with short circuit protection
- Undervoltage Lockout (UVLO) with hysteresis for both VCC and Vref
- Soft-Start capability with charge and discharge currents
- Separate pins for VC and Power Ground to reduce switching transient noise
Applications
The MC34025DWG is designed for use in various power supply applications, including:
- Off-Line Converters
- DC-to-DC Converters
- High-Frequency Switching Power Supplies
- Power MOSFET Drivers
Its high-speed and fixed-frequency operation make it suitable for applications requiring efficient and reliable power management.
Q & A
- What is the primary function of the MC34025DWG?
The MC34025DWG is a high-speed, fixed-frequency, double-ended pulse width modulator (PWM) controller designed for off-line and DC-to-DC converter applications.
- What is the maximum power supply voltage for the MC34025DWG?
The maximum power supply voltage (VCC) is 30 V.
- What is the typical reference output voltage of the MC34025DWG?
The typical reference output voltage (Vref) is 5.1 V.
- What is the propagation delay from the current limit/shutdown to the output?
The propagation delay is typically 50 ns and can be up to 80 ns.
- What are the key protective features of the MC34025DWG?
The key protective features include input and reference undervoltage lockouts, cycle-by-cycle current limiting, and a latch for single pulse metering.
- How does the soft-start feature work in the MC34025DWG?
The soft-start feature involves charging and discharging a capacitor to gradually increase the output voltage, preventing sudden spikes during startup.
- What is the purpose of the separate VC and Power Ground pins?
The separate VC and Power Ground pins help in reducing switching transient noise imposed on the control circuitry.
- What is the maximum operating junction temperature for the MC34025DWG?
The maximum operating junction temperature is 150°C.
- What are the typical applications of the MC34025DWG?
The MC34025DWG is typically used in off-line converters, DC-to-DC converters, and high-frequency switching power supplies.
- How does the undervoltage lockout (UVLO) work in the MC34025DWG?
The UVLO senses both VCC and Vref, disabling the outputs if either voltage falls below a specified threshold and re-enabling them once the voltage exceeds the startup threshold.
- What is the significance of the wide bandwidth error amplifier in the MC34025DWG?
The wide bandwidth error amplifier provides high gain and bandwidth, allowing for precise control and stability in the power supply system.
