Overview
The UC3843AD1 is a high-performance current mode PWM (Pulse Width Modulation) controller produced by STMicroelectronics. Although this component is now obsolete and no longer manufactured, it was widely used in various power supply and DC-DC converter applications. The UC3843AD1 is part of the UC384xA family, which provides the necessary features for implementing off-line or DC-DC fixed frequency current mode control schemes with a minimal external parts count.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage (low impedance source) | 30 | V |
| Output Current | ±1 | A |
| Output Energy (capacitive load) | 5 | µJ |
| Analog Inputs (pins 2, 3) | – 0.3 to 5.5 | V |
| Error Amplifier Output Sink Current | 10 | mA |
| Power Dissipation at Tamb ≤ 25 °C (DIP-8) | 1.25 | W |
| Power Dissipation at Tamb ≤ 25 °C (SO-8) | 800 | mW |
| Storage Temperature Range | – 65 to 150 | °C |
| Junction Operating Temperature | – 40 to 150 | °C |
| Lead Temperature (soldering 10s) | 300 | °C |
| Under-Voltage Lockout Start Threshold | 7.8 to 9.0 | V |
| Maximum Duty Cycle | 94 to 100% | % |
| Start-up Current | 0.3 to 0.5 | mA |
| Operating Supply Current | 12 to 17 | mA |
Key Features
- Trimmed oscillator discharge current for precise duty cycle control.
- Current mode operation up to 500 kHz with automatic feed-forward compensation.
- Latching PWM for cycle-by-cycle current limiting.
- Internally trimmed reference with under-voltage lockout and hysteresis.
- High current totem pole output stage designed to source or sink high peak current.
- Low start-up current (< 0.5 mA) and double pulse suppression.
- Output directly drives the gate of a power MOSFET with peak currents up to 1 A.
- Under-voltage lockout with hysteresis to ensure stable operation.
Applications
The UC3843AD1 is suitable for various power supply and DC-DC converter applications, including:
- Off-line power supplies.
- DC-DC converters.
- Switch-mode power supplies.
- High-frequency power conversion systems.
Q & A
- What is the UC3843AD1?
The UC3843AD1 is a high-performance current mode PWM controller produced by STMicroelectronics.
- Why is the UC3843AD1 obsolete?
The UC3843AD1 is no longer manufactured and has been replaced by other models or substitutes.
- What are the key features of the UC3843AD1?
Key features include trimmed oscillator discharge current, current mode operation up to 500 kHz, latching PWM, internally trimmed reference, and high current totem pole output stage.
- What is the maximum duty cycle of the UC3843AD1?
The maximum duty cycle is 94 to 100%.
- What is the under-voltage lockout start threshold for the UC3843AD1?
The under-voltage lockout start threshold is between 7.8 V and 9.0 V.
- What is the start-up current of the UC3843AD1?
The start-up current is between 0.3 mA and 0.5 mA.
- What is the operating supply current of the UC3843AD1?
The operating supply current is between 12 mA and 17 mA.
- What are the typical applications of the UC3843AD1?
Typical applications include off-line power supplies, DC-DC converters, switch-mode power supplies, and high-frequency power conversion systems.
- How does the UC3843AD1 drive power MOSFETs?
The UC3843AD1 directly drives the gate of a power MOSFET with peak currents up to 1 A.
- What is the thermal resistance junction-ambient for the UC3843AD1 in SO-8 package?
The thermal resistance junction-ambient for the SO-8 package is 150 °C/W.
