Overview
The UC3845BVD1 is a high-performance current mode controller produced by onsemi. 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 stage ideal for driving power MOSFETs.
The device is available in various package types, including 8-pin dual-in-line and surface mount (SOIC-8) as well as 14-pin surface mount (SOIC-14) with separate power and ground pins for the totem pole output stage. The UC3845BVD1 is tailored for lower voltage applications with undervoltage lockout (UVLO) thresholds of 8.5V (on) and 7.6V (off), making it suitable for a wide range of power management needs.
Key Specifications
| Characteristic | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Oscillator Frequency | fOSC | 48 | 250 | 275 | kHz |
| Output Current | IOUT | - | 1 | - | A |
| Output Voltage | VOUT | 4.9 | 5.0 | 5.1 | V |
| Minimum Operating Temperature | Tmin | -40 | - | - | °C |
| Maximum Operating Temperature | Tmax | - | - | 105 | °C |
| Duty Cycle Maximum | DC(max) | - | - | 50 | % |
| UVLO Thresholds | - | 8.5V (on), 7.6V (off) | - | - | 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 UC3845BVD1 is designed for various power management applications, including:
- Off-Line Converters
- DC-DC Converters
- Step-Up Charge Pump Converters
- Voltage-Inverting Charge Pump Converters
- Flyback Regulators
Q & A
- What is the typical oscillator frequency of the UC3845BVD1?
The typical oscillator frequency is 250 kHz.
- What are the UVLO thresholds for the UC3845BVD1?
The UVLO thresholds are 8.5V (on) and 7.6V (off).
- What is the maximum output current of the UC3845BVD1?
The maximum output current is 1 A.
- What is the operating temperature range for the UC3845BVD1?
The operating temperature range is from -40°C to 105°C.
- Is the UC3845BVD1 Pb-Free and RoHS Compliant?
Yes, the UC3845BVD1 is Pb-Free and RoHS Compliant.
- What types of packages are available for the UC3845BVD1?
The device is available in 8-pin dual-in-line and surface mount (SOIC-8) as well as 14-pin surface mount (SOIC-14) packages.
- What is the purpose of the internal flip-flop in the UC3845BVD1?
The internal flip-flop blanks the output off every other oscillator cycle, allowing output deadtimes to be programmed from 50% to 70%.
- How does the current sense comparator work in the UC3845BVD1?
The current sense comparator operates as a current mode controller, where output switch conduction is initiated by the oscillator and terminated when the peak inductor current reaches the threshold level established by the error amplifier output.
- What are some typical applications for the UC3845BVD1?
Typical applications include off-line converters, DC-DC converters, step-up charge pump converters, voltage-inverting charge pump converters, and flyback regulators.
- Does the UC3845BVD1 support automatic feed forward compensation?
Yes, the UC3845BVD1 supports automatic feed forward compensation.
