Overview
The UC3844BVD1R2G is a high-performance, fixed-frequency current mode controller produced by onsemi. It is part of the UC3844B and UC3845B series, which are specifically designed for off-line and DC-DC converter applications. These controllers offer a cost-effective solution with minimal external components, making them ideal for a variety of power supply designs.
The device features an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem pole output stage. This configuration is well-suited for driving power MOSFETs and includes several 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 | ||
| Output Voltage Swing High State | VOH | 6.2 | V | ||
| Output Voltage Swing Low State | VOL | 1.1 | V | ||
| UVLO Thresholds (On/Off) | 16V / 10V | 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 UC3844BVD1R2G is designed for off-line and DC-DC converter applications, making it suitable for a wide range of power supply designs. It is particularly useful in:
- Switch-Mode Power Supplies
- DC-DC Converters
- High-Efficiency Power Conversion Systems
- Industrial Power Supplies
- Automotive Power Systems
Q & A
- What is the primary function of the UC3844BVD1R2G?
The UC3844BVD1R2G 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 UC3844BVD1R2G?
The oscillator frequency is guaranteed at 250 kHz.
- What are the UVLO thresholds for the UC3844BVD1R2G?
The UVLO thresholds are 16V (on) and 10V (off) for the UCX844B series.
- How is the output deadtime adjustable?
The output deadtime is adjustable from 50% to 70% using the internal flip-flop and CT discharge period.
- What protective features are included in the UC3844BVD1R2G?
The device includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What is the maximum output current of the UC3844BVD1R2G?
The maximum output current is 1.0 A.
- Is the UC3844BVD1R2G Pb-Free and RoHS Compliant?
Yes, the device is Pb-Free and RoHS Compliant.
- What are the typical operating temperatures for the UC3844BVD1R2G?
The operating temperature range is from -40°C to +105°C for the UC3844BV series.
- How is the oscillator frequency programmed?
The oscillator frequency is programmed by the values selected for the timing components RT and CT.
- Can the UC3844BVD1R2G be frequency-locked to an external system clock?
Yes, it can be frequency-locked by applying a clock signal to the circuit as described in the datasheet.
