Overview
The UC3842BD is a high-performance fixed frequency current-mode PWM controller from Onsemi, designed for reliable DC/DC converters and adaptable voltage control. This device is particularly suited for various industrial and automotive applications due to its robust features for power conversion.
Key Specifications
| Parameter | Symbol | Value | Unit |
|---|---|---|---|
| Supply Voltage | VCC | 30 | V |
| Output Current (Source or Sink) | IO | ±1 | A |
| Current Sense and Voltage Feedback Inputs | Vin | -0.3 to +5.5 | V |
| Error Amp Output Sink Current | ISINK (E.A) | 10 | mA |
| Maximum Power Dissipation @ TA = 25°C (8-pin SOIC) | PD | 460 | mW |
| Thermal Resistance, Junction-to-Air (8-pin SOIC) | |||
| Reference Output Voltage (IO = 1.0 mA, TJ = 25°C) | Vref | 4.95 to 5.05 | V |
| Line Regulation (VCC = 12 V to 25 V) | Regline | ±2.0 to ±20 | mV |
| Load Regulation (IO = 1.0 mA to 20 mA) | Regload | ±3.0 to ±25 | mV |
Key Features
- High Accuracy: Ensures precise output voltage and current control.
- Fast Response Time: Enables rapid adaptation to load changes and variations in the reference input.
- Wide Operating Range: Compatible with various operating conditions, from -40°C to +125°C.
- Trimmed Oscillator: For precise duty cycle control.
- Temperature Compensated Reference: Provides stable reference voltage across temperature variations.
- High Gain Error Amplifier: For precise voltage loop regulation.
- Current Sensing Comparator: For cycle-by-cycle current limiting.
- High Current Totem Pole Output: Ideally suited for driving power MOSFETs.
- Undervoltage Lockout with Hysteresis: Protects against low input voltages.
- Low Startup and Operating Current: Efficient power management.
Applications
- Distributed Power Systems: Suitable for DC/DC converters and adaptable voltage control in distributed power systems.
- Automotive Systems: Used in automotive applications, such as ignition and charging circuits, where high accuracy and fast response time are crucial.
- Standalone Power Supplies: Can be used in standalone power supplies and battery management systems.
- Complex Power Management Systems: Suitable as a component in complex power management systems.
Q & A
- What is the UC3842BD?
The UC3842BD is a fixed frequency current-mode PWM controller integrated circuit designed for use in power supply and power management applications. - How does the UC3842BD work?
The UC3842BD works by regulating the output voltage of power supplies through pulse-width modulation (PWM) control, operating in a current-mode control architecture. - What are the key pins and their functions on the UC3842BD?
The key pins include VCC (power supply), CS (current sense input), RT and CT (external timing components), COMP (error amplifier output), EA and VC (error amplifier inputs), OUT (output pin for driving an external power MOSFET), and GND (ground pin). - What are the maximum operating conditions for the UC3842BD?
The UC3842BD operates within a temperature range of -40°C to +125°C and has a maximum supply voltage of 30V. - What are the pros and cons of using the UC3842BD?
Pros include reliable performance, current-mode control, wide application range, efficient power management, and simple external circuitry. Cons include the need for additional external components and sensitivity to noise. - Are there any equivalents or alternatives to the UC3842BD?
Alternatives include the UC3843 from Texas Instruments, the SG3524 from STMicroelectronics, and the TL494 from Texas Instruments. - What is the typical oscillator frequency of the UC3842BD?
The oscillator frequency can be programmed but is typically guaranteed at 250 kHz. - What protective features does the UC3842BD have?
The device includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, programmable output deadtime, and a latch for single pulse metering. - What packages are available for the UC3842BD?
The UC3842BD is available in 8-pin dual-in-line and surface mount (SO-8) packages, as well as a 14-pin surface mount (SO-14) package. - How do I ensure proper operation of the UC3842BD?
To ensure proper operation, connect the IN+ pin to the reference voltage source, the IN- pin to the feedback signal, and use the OUT pin to drive the power stage components according to your desired output voltage and current levels.
