Overview
The UC3844BD1G is a high-performance, fixed-frequency current mode controller produced by onsemi. This integrated circuit is specifically designed for off-line and DC-DC converter applications, offering a cost-effective solution with minimal external components. It features an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem pole output ideal for driving a power MOSFET. The device includes protective features such as input and reference undervoltage lockouts, cycle-by-cycle current limiting, and adjustable output deadtimes.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Bias and Driver Voltages | VCC, VC | - | - | 36 | V |
| Total Power Supply and Zener Current | ICC + IZ | - | - | 30 | mA |
| Output Current, Source or Sink | IO | - | - | 1.0 | A |
| Output Energy (Capacitive Load per Cycle) | W | - | - | 5.0 | μJ |
| Reference Output Voltage | Vref | 4.95 | 5.0 | 5.05 | V |
| Oscillator Frequency | fOSC | - | 250 kHz | - | kHz |
| Startup Threshold | Vth | 15 | - | 16 | V |
| Minimum Operating Voltage After Turn-On | VCC(min) | 9.0 | - | 10 | V |
Key Features
- Trimmed Oscillator for Precise Frequency Control
- Oscillator Frequency Guaranteed at 250 kHz
- Current Mode Operation to 500 kHz Output Switching Frequency
- Output Deadtime Adjustable from 50% to 70%
- Automatic Feed Forward Compensation
- Latching PWM for Cycle-By-Cycle Current Limiting
- Internally Trimmed Reference with Undervoltage Lockout
- High Current Totem Pole Output
- Undervoltage Lockout with Hysteresis
- Low Startup and Operating Current
- Pb-Free and RoHS Compliant
Applications
The UC3844BD1G is designed for off-line and DC-DC converter applications. It is particularly suitable for power supply designs that require high performance, reliability, and minimal external components. These include:
- Switch-Mode Power Supplies
- DC-DC Converters
- High-Efficiency Power Conversion Systems
- Automotive and Industrial Power Systems
Q & A
- What is the primary function of the UC3844BD1G?
The UC3844BD1G is a high-performance, fixed-frequency current mode controller designed for off-line and DC-DC converter applications.
- What is the typical oscillator frequency of the UC3844BD1G?
The oscillator frequency is guaranteed at 250 kHz.
- What are the key protective features of the UC3844BD1G?
The device includes input and reference undervoltage lockouts, cycle-by-cycle current limiting, and adjustable output deadtimes.
- What is the maximum output current of the UC3844BD1G?
The maximum output current is 1.0 A.
- How is the output deadtime adjusted in the UC3844BD1G?
The output deadtime is adjustable from 50% to 70% using the timing components RT and CT.
- What are the startup and minimum operating voltages for the UC3844BD1G?
The startup threshold is 15 V, and the minimum operating voltage after turn-on is 9.0 V.
- Is the UC3844BD1G Pb-Free and RoHS Compliant?
- What types of packages are available for the UC3844BD1G?
The device is available in 8-pin dual-in-line and surface mount (SOIC-8) packages, as well as a 14-pin plastic surface mount (SOIC-14) package.
- How does the undervoltage lockout feature work in the UC3844BD1G?
The undervoltage lockout feature includes separate comparators for the positive power supply terminal (VCC) and the reference output (Vref), each with built-in hysteresis to prevent erratic output behavior.
- What are some common applications of the UC3844BD1G?
