Overview
The UC3845BVD from onsemi is a high-performance current mode PWM (Pulse Width Modulation) controller. It is specifically designed for off-line and DC-DC converter applications, offering a cost-effective solution with minimal external components. This integrated circuit features an oscillator, a temperature-compensated reference, a high-gain error amplifier, a current sensing comparator, and a high-current totem pole output, making it ideal for driving power MOSFETs. The device is available in various packages, including 8-pin and 14-pin surface mount (SOIC) configurations.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage | VCC | 8.2 | - | 25 | V |
| Oscillator Frequency | fOSC | - | 250 kHz | - | kHz |
| Output Switching Frequency | - | - | 500 kHz | - | kHz |
| Maximum Duty Cycle | DC(max) | - | - | 50% | % |
| UVLO Turn-On Threshold | - | 8.5 | - | V | |
| UVLO Turn-Off Threshold | - | 7.6 | - | V | |
| Typical Quiescent Current | ICC | - | 0.3 | - | mA |
| Output Current - Sink | ISink | - | 2.0 | - | mA |
| Output Current - Source | ISource | - | 1.0 | - | mA |
| Operating Temperature Range | TA | -40 | - | 105 | °C |
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
- AEC-Q100 Qualified and PPAP Capable for Automotive and Other Applications
Applications
The UC3845BVD is designed for use in off-line and DC-DC converter applications. It is particularly suited for:
- Switch Mode Power Supplies
- DC-DC Converters
- High-Efficiency Power Conversion Systems
- Automotive Power Systems (with AEC-Q100 qualification)
- Industrial Power Supplies
Q & A
- What is the typical operating frequency of the UC3845BVD?
The oscillator frequency is typically 250 kHz, but the output switching frequency can go up to 500 kHz.
- What are the UVLO thresholds for the UC3845BVD?
The UVLO turn-on threshold is 8.5V, and the turn-off threshold is 7.6V.
- What is the maximum duty cycle of the UC3845BVD?
The maximum duty cycle is 50%.
- What are the key protective features of the UC3845BVD?
The device includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- Is the UC3845BVD RoHS compliant?
Yes, the UC3845BVD is Pb-Free and RoHS compliant.
- What are the typical quiescent current and startup current of the UC3845BVD?
The typical quiescent current is 0.3 mA, and the startup current is typically low, around 0.3 mA at VCC = 6.5 V for UCX845B.
- What is the operating temperature range of the UC3845BVD?
The operating temperature range is from -40°C to +105°C.
- Can the UC3845BVD be used in automotive applications?
Yes, the UC3845BVD is AEC-Q100 qualified and PPAP capable, making it suitable for automotive and other demanding applications.
- What package options are available for the UC3845BVD?
The device is available in 8-pin and 14-pin surface mount (SOIC) packages.
- How is the output deadtime adjustable in the UC3845BVD?
The output deadtime can be adjusted from 50% to 70% using an internal flip-flop and the CT discharge period.
