Overview
The UC3844BN, produced by STMicroelectronics, is a high-performance current mode PWM controller. This IC is part of the UC384xB family, which is designed for off-line and DC-DC converter applications. It offers a cost-effective solution with a minimal number of external components. The UC3844BN features a trimmed oscillator for precise frequency control, automatic feed-forward compensation, and latching PWM for cycle-by-cycle current limiting. It also includes an internally trimmed reference with undervoltage lockout and a high current totem pole output stage suitable for driving N-Channel MOSFETs.
Key Specifications
| Parameter | Min | Typ | Max | Unit |
|---|---|---|---|---|
| Supply Voltage (Vi) | - | - | 30 | V |
| Output Current (IO) | - | - | ±1 | A |
| Output Energy (EO) | - | - | 5 | µJ |
| Oscillator Frequency | - | 250 | - | kHz |
| Reference Voltage (VREF) | 4.90 | 5.00 | 5.10 | V |
| Under-Voltage Lockout Start Threshold | 14.5 | 16 | 17.5 | V |
| Maximum Duty Cycle | 47 | 48 | 50 | % |
| Start-up Current (Ist) | 0.3 | 0.5 | - | mA |
| Operating Supply Current (Ii) | 12 | 17 | - | mA |
Key Features
- Trimmed Oscillator: Provides precise frequency control up to 500 kHz.
- Current Mode Operation: Supports current mode control schemes.
- Automatic Feed-Forward Compensation: Enhances stability and performance.
- Latching PWM: Offers cycle-by-cycle current limiting.
- Internally Trimmed Reference: With undervoltage lockout and hysteresis.
- High Current Totem Pole Output: Suitable for driving N-Channel MOSFETs.
- Low Start-Up and Operating Current: Minimizes power consumption.
- Protective Features: Includes input and reference undervoltage lockouts, and a latch for single pulse metering.
- External Clock Synchronization: Allows for synchronization with external clocks.
Applications
The UC3844BN is designed for use in various power conversion applications, including:
- Off-line power supplies
- DC-DC converters
- Switch-mode power supplies
- High-efficiency power management systems
Q & A
- What is the typical oscillator frequency of the UC3844BN?
The typical oscillator frequency is 250 kHz.
- What is the maximum duty cycle for the UC3844BN?
The maximum duty cycle is 50%.
- What is the start-up current for the UC3844BN?
The start-up current is typically 0.5 mA.
- What is the operating supply current for the UC3844BN?
The operating supply current is typically 17 mA.
- Does the UC3844BN have undervoltage lockout protection?
Yes, it includes undervoltage lockout with hysteresis.
- Can the UC3844BN be synchronized with an external clock?
Yes, it supports external clock synchronization.
- What is the maximum output current of the UC3844BN?
The maximum output current is ±1 A.
- What type of output stage does the UC3844BN have?
It has a high current totem pole output stage.
- What is the reference voltage of the UC3844BN?
The reference voltage is typically 5.00 V.
- What are the typical applications for the UC3844BN?
It is used in off-line power supplies, DC-DC converters, and switch-mode power supplies.
