Overview
The UC2845D8TRG4 is a single-ended current-mode PWM (Pulse Width Modulation) controller produced by Texas Instruments. It is part of the UCx84x family of control integrated circuits, designed to implement off-line and DC-to-DC fixed-frequency current-mode control schemes with a minimal number of external components. This device is optimized for high-performance power supply applications, offering features such as low start-up current, automatic feedforward compensation, and enhanced load-response characteristics.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| VCC (Low impedance source) | - | - | 30 | V |
| IVCC (Self Limiting) | - | - | 30 mA | - |
| VFB and VISENSE (Analog input voltage) | -0.3 | - | 6.3 | V |
| IOUTPUT (Output drive current) | - | - | ±1 A | - |
| TJ (Junction temperature) | - | - | 150 °C | - |
| Tstg (Storage temperature) | -65 | - | 150 °C | - |
| TA (Operating free-air temperature) | -40 | - | 85 °C | - |
| fOSC (Oscillator frequency) | 100 kHz | - | 500 kHz | - |
| VREF (Reference voltage) | 4.95 V | 5 V | 5.05 V | - |
Key Features
- Optimized for off-line and DC-to-DC converters
- Low start-up current (< 1 mA)
- 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 500-kHz operation
- Error amplifier with low output resistance
Applications
- Switching regulators of any polarity
- Transformer-coupled DC-DC converters
- Off-line power supplies
- DC-DC applications
Q & A
- What is the operating temperature range of the UC2845D8TRG4?
The UC2845D8TRG4 operates from –40°C to 85°C.
- What is the maximum oscillator frequency of the UC2845D8TRG4?
The maximum oscillator frequency is up to 500 kHz.
- What is the reference voltage of the UC2845D8TRG4?
The reference voltage is 5 V, with a tolerance of 4.95 V to 5.05 V.
- Does the UC2845D8TRG4 have undervoltage lockout (UVLO) protection?
- What are the package options for the UC2845D8TRG4?
The UC2845D8TRG4 is available in SOIC (8-pin) and other package options such as PDIP and CFP).
- What is the maximum output drive current of the UC2845D8TRG4?
The maximum output drive current is ±1 A).
- Does the UC2845D8TRG4 support pulse-by-pulse current limiting?
- What is the purpose of the error amplifier in the UC2845D8TRG4?
The error amplifier is used to control the power converter voltage-feedback loop for stability).
- Can the UC2845D8TRG4 be used in transformer-coupled DC-DC converters?
- How is the switching frequency set in the UC2845D8TRG4?
The switching frequency can be set using the timing resistor (RRT) and timing capacitor (CCT) connected to the RT/CT pin).
