Overview
The LM5045SQ/NOPB PWM controller, produced by Texas Instruments, is a highly integrated device designed to implement full-bridge topology power converters using either current mode or voltage mode control. This controller is intended to operate on the primary side of an isolated DC-DC converter with input voltage up to 100 V. It provides dual 2-A high-side and low-side gate drivers for the four external bridge MOSFETs, as well as control signals for the secondary-side synchronous rectifier MOSFETs. The device features intelligent start-up of the synchronous rectifiers, allowing monotonic turn-on of the power converter even with prebias load conditions. Additional features include cycle-by-cycle current limiting, hiccup mode restart, programmable soft-start, and a 2-MHz capable oscillator with synchronization capability and thermal shutdown.
Key Specifications
| Parameter | Conditions | Min | Typ | Max | Units |
|---|---|---|---|---|---|
| Input Voltage | 14 | 100 | V | ||
| Gate Driver Current (High-Side) | 1.5 | 2 | A | ||
| Gate Driver Current (Low-Side) | 1.5 | 2 | A | ||
| Oscillator Frequency | RT = 25 kΩ | 185 | 200 | 215 | kHz |
| Oscillator Frequency | RT = 10 kΩ | 420 | 480 | 540 | kHz |
| Thermal Shutdown | 160 | °C | |||
| Package Type | WQFN28 |
Key Features
- High-Voltage Start-Up Regulator: Allows the input pin (VIN) to be connected directly to the supply voltage over a wide range from 14 V to 100 V.
- Integrated MOSFET Drivers: Provides dual 2-A high-side and low-side gate drivers for the four external bridge MOSFETs and control signals for the secondary-side synchronous rectifier MOSFETs.
- Programmable Dead-Time: External resistors program the leading and trailing edge dead-time between the main and synchronous rectifier control signals.
- Intelligent Start-Up of Synchronous Rectifiers: Allows monotonic turn-on of the power converter even with prebias load conditions.
- Cycle-by-Cycle Current Limiting and Hiccup Mode Restart: Protects the power components from load transients and limits average power dissipation during extended overload conditions.
- Programmable Soft-Start and Synchronous Rectifier Soft-Start: Ensures smooth start-up of the power converter.
- 2-MHz Capable Oscillator with Synchronization Capability: Supports high-frequency operation and synchronization with external signals.
- Thermal Shutdown: Protects the device from overheating by shutting down at 160°C.
Applications
- AC/DC Adaptors/Chargers: For cell phones, cordless phones, PDAs, e-books, and portable media players.
- Set-top Boxes and DVD Players: For power conversion in consumer electronics.
- Linear Adapter Replacements: For more efficient power conversion in various applications.
- Military and Radar Systems: For high-reliability power conversion in military and radar applications.
- Solar Power Inverters and Micro-Inverters: For efficient power conversion in renewable energy systems.
- Telecom and Server Power Supplies: For high-density power conversion in telecommunications and server systems.
Q & A
- What is the maximum input voltage for the LM5045SQ/NOPB?
The maximum input voltage is up to 100 V.
- What type of control modes does the LM5045SQ/NOPB support?
The device supports both current mode and voltage mode control.
- What is the maximum frequency of the oscillator in the LM5045SQ/NOPB?
The oscillator is capable of operating up to 2 MHz.
- How does the LM5045SQ/NOPB protect against overcurrent conditions?
The device features cycle-by-cycle current limiting and hiccup mode restart to protect against overcurrent conditions.
- What is the thermal shutdown temperature of the LM5045SQ/NOPB?
The thermal shutdown temperature is 160°C.
- What type of package does the LM5045SQ/NOPB come in?
The device is packaged in a 28-pin WQFN (Wafer Level Quad Flat No-Lead) package.
- What are some common applications for the LM5045SQ/NOPB?
Common applications include AC/DC adaptors, set-top boxes, DVD players, solar power inverters, and telecom power supplies.
- How does the LM5045SQ/NOPB handle prebias load conditions during start-up?
The device features intelligent start-up of the synchronous rectifiers, allowing monotonic turn-on of the power converter even with prebias load conditions.
- Can the LM5045SQ/NOPB be synchronized with external signals?
Yes, the 2-MHz capable oscillator has synchronization capability.
- What is the purpose of the high-voltage start-up regulator in the LM5045SQ/NOPB?
The high-voltage start-up regulator allows the input pin to be connected directly to the supply voltage over a wide range from 14 V to 100 V.
