Overview
The UC3845BNG is a high-performance fixed frequency current mode controller produced by onsemi. It is part of the UC3844B and UC3845B series, 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 management needs.
The UC3845BNG features an oscillator, a temperature-compensated reference, a high gain error amplifier, a current sensing comparator, and a high current totem pole output. This configuration is well-suited for driving power MOSFETs in various power conversion applications.
Key Specifications
| Parameter | Symbol | Min | Typ | Max | Unit |
|---|---|---|---|---|---|
| Supply Voltage | VCC | - | - | 30 | V |
| Output Current | IO | - | - | ±1 | A |
| Oscillator Frequency | fOSC | - | 250 | - | kHz |
| UVLO Thresholds (On/Off) | Vth | 8.5 / 7.6 | - | - | V |
| Output Deadtime Adjustable | - | 50% to 70% | - | - | % |
| Power Dissipation at TA≤25°C (8DIP) | PD | - | - | 1200 | mW |
| Storage Temperature Range | TSTG | -65 | - | 150 | °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 Packages are Available and RoHS Compliant
Applications
The UC3845BNG is designed for off-line and DC-DC converter applications, including but not limited to:
- Off-line power supplies
- DC-DC converters (e.g., boost, flyback, forward)
- Switch-mode power supplies
- Power management systems requiring high efficiency and reliability
Q & A
- What is the primary function of the UC3845BNG?
The UC3845BNG is a high-performance fixed frequency current mode controller designed for off-line and DC-DC converter applications.
- What are the UVLO thresholds for the UC3845BNG?
The UVLO thresholds for the UC3845BNG are 8.5V (on) and 7.6V (off).
- What is the maximum oscillator frequency of the UC3845BNG?
The oscillator frequency is guaranteed at 250 kHz, and the device can operate up to 500 kHz output switching frequency.
- What types of packages are available for the UC3845BNG?
The UC3845BNG is available in 8-pin dual-in-line (PDIP-8) and surface mount (SOIC-8 and SOIC-14) packages.
- Does the UC3845BNG have protective features?
Yes, it includes input and reference undervoltage lockouts with hysteresis, cycle-by-cycle current limiting, and a latch for single pulse metering.
- What is the output deadtime adjustment range for the UC3845BNG?
The output deadtime can be adjusted from 50% to 70%.
- Is the UC3845BNG Pb-free and RoHS compliant?
Yes, the UC3845BNG is Pb-free and RoHS compliant.
- What is the maximum power dissipation for the UC3845BNG in an 8DIP package?
The maximum power dissipation at TA≤25°C for the 8DIP package is 1200 mW.
- What is the storage temperature range for the UC3845BNG?
The storage temperature range is -65°C to +150°C.
- How does the UC3845BNG handle current limiting?
The UC3845BNG features latching PWM for cycle-by-cycle current limiting.
