Overview
The UC3845ADWTR is a high-performance fixed-frequency current-mode PWM controller produced by Texas Instruments. It is part of the UCx84xA family, which is a pin-for-pin compatible improved version of the UCx84x family. This controller is specifically designed for offline and DC-to-DC converter applications, offering a cost-effective solution with minimal external components required. The UC3845ADWTR features a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high-gain error amplifier, and a high-current totem pole output for driving power MOSFETs.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Package Type | 16-SOIC | |
| Pins | 16 | |
| Operating Temperature Range | 0 to 70 | °C |
| Supply Voltage (VCC) | 7.6 to 30 | V |
| Output Current (IO) | ±1 | A |
| Oscillation Frequency | Up to 500 kHz | |
| Start-Up Current (IST) | < 0.5 mA | |
| Operating Supply Current (ICC(OPR)) | 14 to 17 mA | |
| UVLO Thresholds | 8.5 V (on), 7.9 V (off) | |
| Maximum Duty Cycle | 50% |
Key Features
- Current Mode Operation up to 500 kHz Output Switching Frequency
- Output Deadtime Adjustable from 50% to 70%
- Automatic Feed Forward Compensation
- Latching PWM for Cycle-by-Cycle Current Limiting
- Internally Trimmed Reference with Undervoltage Lockout
- High Current Totem Pole Output
- Input Undervoltage Lockout with Hysteresis
- Low Startup and Operating Current
- Direct Interface with Power MOSFETs
- Pb-Free Packages Available
Applications
The UC3845ADWTR is designed for various power supply applications, including:
- Offline and DC-to-DC converters
- Switched-mode power supplies
- Power MOSFET drivers
- Low voltage applications requiring high efficiency and reliability
Q & A
- What is the UC3845ADWTR used for?
The UC3845ADWTR is used for controlling current-mode or switched-mode power supplies, particularly in offline and DC-to-DC converter applications.
- What is the operating temperature range of the UC3845ADWTR?
The operating temperature range is from 0 to 70°C.
- What is the maximum output switching frequency of the UC3845ADWTR?
The maximum output switching frequency is up to 500 kHz.
- What are the UVLO thresholds for the UC3845ADWTR?
The UVLO thresholds are 8.5 V (on) and 7.9 V (off).
- Does the UC3845ADWTR have a high-current output stage?
Yes, it has a high-current totem pole output stage capable of sourcing and sinking peak currents up to 1.0 A.
- What is the startup current of the UC3845ADWTR?
The startup current is less than 0.5 mA.
- Can the UC3845ADWTR operate with a 100% duty cycle?
No, the UC3845ADWTR can operate with a maximum duty cycle of 50%.
- Is the UC3845ADWTR available in Pb-free packages?
Yes, Pb-free packages are available.
- What type of compensation does the UC3845ADWTR offer?
The UC3845ADWTR offers automatic feedforward compensation and loop compensation through the error amplifier output.
- How is the oscillator frequency programmed in the UC3845ADWTR?
The oscillator frequency is programmed by connecting a resistor (RT) to Vref and a capacitor (CT) to ground.
