Overview
The UC3842BNG is a high-performance current mode controller produced by onsemi. It is part of the UC3842B series, which is specifically designed for off-line and DC-DC converter applications. This controller offers a cost-effective solution with minimal external components, making it an ideal choice for a variety of power supply designs.
The UC3842BNG 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 suitable for driving power MOSFETs. Additionally, it includes protective features such as input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering.
Key Specifications
| Parameter | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage | VCC | - | - | 30 | V |
| Output Current (Source or Sink) | IO | - | - | 1.0 | A |
| Output Energy (Capacitive Load per Cycle) | - | - | - | 5.0 | μJ |
| Reference Output Voltage (IO = 1.0 mA, TJ = 25°C) | Vref | 4.95 | 5.0 | 5.05 | V |
| Line Regulation (VCC = 12 V to 25 V) | Regline | - | - | 2.0 | mV |
| Load Regulation (IO = 1.0 mA to 20 mA) | Regload | - | - | 3.0 | mV |
| Temperature Stability | TS | - | - | 0.2 | mV/°C |
| Oscillator Frequency (TJ = 25°C) | fosc | 47 | 50 | 52 | kHz |
| Output Voltage Low State (ISink = 20 mA) | VOL | 0.8 | - | 1.1 | V |
| Output Voltage High State (ISource = 20 mA) | VOH | 12 | - | 13.5 | V |
| Startup Threshold (VCC) | - | - | 6.0 | V |
Key Features
- Trimmed Oscillator: For precise duty cycle control.
- Temperature Compensated Reference: Ensures stable operation over a wide temperature range.
- High-Gain Error Amplifier: Provides accurate feedback control.
- Current Sensing Comparator: For cycle-by-cycle current limiting.
- High-Current Totem Pole Output: Suitable for driving power MOSFETs.
- Protective Features: Includes input and reference undervoltage lockouts with hysteresis, programmable output deadtime, and a latch for single pulse metering.
- Low Startup Current: Minimizes power consumption during startup.
- Maximum Duty Clamp: Ensures safe operation by limiting the maximum duty cycle.
Applications
The UC3842BNG is designed for use in various power supply applications, including:
- Off-Line Converters: Suitable for designing power supplies that operate directly from AC mains.
- DC-DC Converters: Ideal for applications requiring efficient DC-DC conversion with minimal external components.
- Switch Mode Power Supplies (SMPS): Used in a wide range of SMPS designs due to its high performance and reliability.
- Power Management Systems: Can be integrated into complex power management systems requiring precise control and protection features.
Q & A
- What is the maximum supply voltage for the UC3842BNG?
The maximum supply voltage (VCC) for the UC3842BNG is 30 V.
- What is the typical oscillator frequency of the UC3842BNG?
The typical oscillator frequency is around 50 kHz, depending on the values of the timing components RT and CT.
- What are the key protective features of the UC3842BNG?
The UC3842BNG includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering.
- What is the maximum output current of the UC3842BNG?
The maximum output current (IO) is 1.0 A.
- What is the reference output voltage of the UC3842BNG?
The reference output voltage (Vref) is typically 5.0 V, with a range of 4.95 V to 5.05 V.
- What are the common package types for the UC3842BNG?
The UC3842BNG is available in 8-pin dual-in-line (DIP) and surface mount (SOIC-8) packages, as well as a 14-pin surface mount (SOIC-14) package.
- What is the operating temperature range for the UC3842BNG?
The operating ambient temperature range is from 0°C to +70°C for the UC3842B, and from -25°C to +85°C for the UC2842B.
- How is the oscillator frequency programmed in the UC3842BNG?
The oscillator frequency is programmed by the values chosen for the timing components RT and CT.
- What is the power dissipation at TA ≤ 25°C for the UC3842BNG in an 8-DIP package?
The power dissipation at TA ≤ 25°C for the 8-DIP package is 1200 mW.
- Does the UC3842BNG have any specific startup requirements?
Yes, the VCC must be adjusted above the startup threshold before setting to the operating voltage.
