Overview
The UC3843BVN is a high-performance fixed frequency current mode controller produced by onsemi. It is part of the UC3842B and UC3843B series, which are specifically designed for off-line and DC-to-DC converter applications. These controllers offer a cost-effective solution with minimal external components, making them ideal for a variety of power management applications. The UC3843BVN features a trimmed oscillator for precise duty cycle control, a temperature-compensated reference, a high-gain error amplifier, and a current sensing comparator. Additionally, it includes protective features such as input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and programmable output deadtime.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Operating Voltage (VCC) | 7.0 | - | 30 | V |
| Output Current (Source or Sink) | - | - | 1.0 | A |
| Oscillator Frequency | - | 250 kHz | - | kHz |
| Reference Output Voltage (Vref) | 4.95 | 5.0 | 5.05 | V |
| UVLO Startup Threshold (VCC) | 8.5 | - | - | V |
| UVLO Minimum Operating Voltage After Turn-On (VCC) | 7.6 | - | - | V |
| Power Supply Current (ICC + IC) | - | - | 0.5 | mA |
| Output Voltage Low State (VOL) | - | - | 0.1 | V |
| Output Voltage High State (VOH) | - | - | 13.5 | V |
Key Features
- Trimmed Oscillator for Precise Frequency Control: Ensures accurate and stable oscillator frequency, guaranteed at 250 kHz.
- Current Mode Operation: Supports operation up to 500 kHz.
- Automatic Feed Forward Compensation: Enhances stability and performance of the controller.
- Latching PWM for Cycle-By-Cycle Current Limiting: Provides robust current limiting and protection.
- Internally Trimmed Reference with Undervoltage Lockout: Includes a temperature-compensated reference and undervoltage lockout with hysteresis.
- High Current Totem Pole Output: Suitable for driving power MOSFETs with high current capability.
- Low Startup and Operating Current: Minimizes power consumption during startup and operation.
- Pb-Free Packages: Available in lead-free packages, adhering to environmental standards.
Applications
The UC3843BVN is designed for various power management applications, including:
- Off-Line Converters: Ideal for high-voltage applications with UVLO thresholds suited for off-line converters.
- DC-to-DC Converters: Suitable for lower voltage DC-to-DC converter applications with specific UVLO thresholds.
- Power Supplies: Used in the design of efficient and reliable power supplies.
- Switch-Mode Power Supplies: Essential for switch-mode power supplies requiring precise control and protection features.
Q & A
- What is the typical oscillator frequency of the UC3843BVN?
The oscillator frequency is guaranteed at 250 kHz.
- What are the UVLO thresholds for the UC3843BVN?
The UVLO thresholds are 8.5 V (on) and 7.6 V (off).
- What is the maximum output current of the UC3843BVN?
The maximum output current is 1.0 A.
- What type of operation does the UC3843BVN support?
The UC3843BVN supports current mode operation up to 500 kHz.
- What protective features are included in the UC3843BVN?
The device includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and programmable output deadtime.
- What is the reference output voltage of the UC3843BVN?
The reference output voltage (Vref) is typically 5.0 V, with a range of 4.95 V to 5.05 V.
- What is the power supply current of the UC3843BVN during startup?
The power supply current (ICC + IC) during startup is typically up to 0.5 mA.
- What are the available package types for the UC3843BVN?
The device is available in 8-pin dual-in-line and surface mount (SO-8) packages, as well as 14-pin plastic surface mount (SO-14) packages.
- Is the UC3843BVN Pb-Free?
Yes, the UC3843BVN is available in Pb-Free packages.
- What is the purpose of the high current totem pole output in the UC3843BVN?
The high current totem pole output is ideally suited for driving power MOSFETs.
