Overview
The UC3845AD8G4 is a fixed-frequency, current-mode PWM (Pulse Width Modulation) controller produced by Texas Instruments. This integrated circuit is specifically designed for off-line and DC-DC converter applications, requiring minimal external components. It features a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem-pole output for driving power MOSFETs.
Key Specifications
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Supply Voltage | VCC | 7.6 to 30 | V |
| Output Current | IO | ±1 | A |
| Analog Input Voltage | V(ANA) | -0.3 to 6.3 | V |
| Error Amp Output Sink Current | ISINK (E.A) | 10 | mA |
| Power Dissipation at TA≤25°C (8-SOIC) | PD | 460 | mW |
| Storage Temperature Range | TSTG | -65 to +150 | °C |
| Operating Temperature Range | TA | 0 to 70 | °C |
| Switching Frequency | fSW | Up to 500 kHz | |
| Maximum Duty Cycle | 48% | ||
| Package/Case | 8-SOIC |
Key Features
- Low start-up current (< 0.5 mA)
- UVLO (Under-Voltage Lockout) with hysteresis (8.5V on, 7.9V off for UC3845)
- Trimmed oscillator for precise duty cycle control
- Temperature-compensated reference
- High-gain error amplifier
- Current sensing comparator
- High-current totem-pole output for driving power MOSFETs
- Maximum duty cycle clamp
- Operating frequency up to 500 kHz
Applications
The UC3845AD8G4 is optimized for various power supply and converter applications, including:
- Off-line power supplies
- DC-DC converters (buck, boost, flyback, forward converters)
- Isolation capable output configurations
Q & A
- What is the typical start-up current of the UC3845AD8G4? The typical start-up current is less than 0.5 mA.
- What are the UVLO thresholds for the UC3845AD8G4? The UVLO thresholds are 8.5V (on) and 7.9V (off).
- What is the maximum operating frequency of the UC3845AD8G4? The maximum operating frequency is up to 500 kHz.
- What is the maximum duty cycle for the UC3845AD8G4? The maximum duty cycle is 48%.
- What types of converters can the UC3845AD8G4 be used in? It can be used in buck, boost, flyback, and forward converters.
- What is the package type of the UC3845AD8G4? The package type is 8-SOIC.
- What is the operating temperature range of the UC3845AD8G4? The operating temperature range is from 0°C to 70°C.
- Does the UC3845AD8G4 have a current sensing comparator? Yes, it does have a current sensing comparator.
- Is the UC3845AD8G4 lead-free and ROHS compliant? Yes, it is lead-free and ROHS compliant.
- What is the supply voltage range for the UC3845AD8G4? The supply voltage range is from 7.6V to 30V.
