Overview
The UC3845AD8TRG4 is a current-mode PWM controller from Texas Instruments, part of the UCx84xA family. This device is optimized for off-line and DC-DC converters, offering several improved features over its predecessors. It is designed to operate within a temperature range of 0°C to 70°C and is available in an 8-pin SOIC (D) package. The UC3845A is known for its low start-up current, trimmed oscillator discharge current, and enhanced load response characteristics, making it a versatile choice for various power supply applications.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Operating Temperature Range | 0 to 70 | °C |
| Package Type | SOIC (D) | - |
| Number of Pins | 8 | - |
| Maximum Operating Voltage (VCC) | 30 | V |
| Maximum Output Current | ±1 | A |
| Oscillator Frequency Range | 100 to 500 | kHz |
| Start-Up Current | < 0.5 | mA |
| Reference Voltage | 4.9 to 5.1 | V |
| Undervoltage Lockout (UVLO) | 8.4V/7.6V | - |
Key Features
- Optimized for off-line and DC-DC converters
- Low start-up current (< 0.5mA)
- Trimmed oscillator discharge current
- Automatic feedforward compensation
- Pulse-by-pulse current limiting
- Enhanced load response characteristics
- Undervoltage lockout with hysteresis
- Double pulse suppression
- High-current totem pole output
- Internally trimmed bandgap reference
- Up to 500kHz operation
- Error amplifier with low output resistance
Applications
- Switching regulators of any polarity
- Transformer-coupled DC-DC converters
- Off-line power supplies
- DC-DC fixed-frequency current-mode control schemes
Q & A
- What is the operating temperature range of the UC3845AD8TRG4?
The operating temperature range is 0°C to 70°C.
- What is the maximum operating voltage for the UC3845AD8TRG4?
The maximum operating voltage (VCC) is 30V.
- What is the start-up current of the UC3845AD8TRG4?
The start-up current is less than 0.5mA.
- What is the oscillator frequency range of the UC3845AD8TRG4?
The oscillator frequency range is 100kHz to 500kHz.
- What type of output stage does the UC3845AD8TRG4 have?
The UC3845AD8TRG4 has a high-current totem pole output stage.
- What is the purpose of the undervoltage lockout (UVLO) in the UC3845AD8TRG4?
The UVLO ensures the device operates only when the input voltage is within a safe range, preventing damage during low voltage conditions.
- Can the UC3845AD8TRG4 be used in DC-DC converters?
- What is the reference voltage of the UC3845AD8TRG4?
The reference voltage is between 4.9V and 5.1V.
- Does the UC3845AD8TRG4 support pulse-by-pulse current limiting?
- How can I set the switching frequency of the UC3845AD8TRG4?
The switching frequency can be set using the timing resistor (RRT) and timing capacitor (CCT) connected to the RT/CT pin.
