Overview
The UC3842BD1, produced by STMicroelectronics, is a high-performance current mode PWM (Pulse Width Modulation) controller. This IC is part of the UC384xB family, designed to implement off-line or DC to DC fixed frequency current mode control schemes with a minimal external parts count. It features a trimmed oscillator for precise frequency control, automatic feed-forward compensation, and latching PWM for cycle-by-cycle current limiting. The UC3842BD1 is suitable for driving N-Channel MOSFETs and is ideal for applications requiring high accuracy and reliability in power supply control.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| Supply Voltage (low impedance source) | 30 | V |
| Output Current | ±1 | A |
| Oscillator Frequency | Up to 500kHz | |
| Reference Voltage | 4.95 - 5.05 | V |
| Under-Voltage Lockout (UVLO) Start Threshold | 16V (on), 10V (off) | V |
| Maximum Duty Cycle | Up to 100% | % |
| Power Dissipation at Tamb ≤ 25°C (Minidip) | 1.25 | W |
| Junction Operating Temperature | -40 to 150 | °C |
| Storage Temperature Range | -65 to 150 | °C |
Key Features
- Trimmed oscillator for precise frequency control up to 500kHz
- Current mode operation with automatic feed-forward compensation
- Latching PWM for cycle-by-cycle current limiting
- Internally trimmed reference with under-voltage lockout and hysteresis
- High current totem pole output stage suitable for driving N-Channel MOSFETs
- Low start-up and operating current (less than 0.5mA start-up current)
- Precision error amplifier with high gain and bandwidth
- Programmable oscillator frequency and maximum output duty cycle using RT and CT components
Applications
The UC3842BD1 is widely used in various power supply applications, including:
- Off-line power supplies
- DC to DC converters
- Switch-mode power supplies
- High-frequency power conversion systems
- Power factor correction (PFC) circuits
Q & A
- What is the primary function of the UC3842BD1?
The UC3842BD1 is a high-performance current mode PWM controller used for implementing off-line or DC to DC fixed frequency current mode control schemes.
- What is the maximum oscillator frequency of the UC3842BD1?
The oscillator frequency can be programmed up to 500kHz.
- What are the under-voltage lockout (UVLO) thresholds for the UC3842BD1?
The UVLO start threshold is 16V (on) and 10V (off).
- What is the maximum duty cycle of the UC3842BD1?
The maximum duty cycle can be up to 100%.
- How much power can the UC3842BD1 dissipate at ambient temperatures up to 25°C?
The power dissipation is 1.25W for the Minidip package.
- What is the junction operating temperature range of the UC3842BD1?
The junction operating temperature range is -40 to 150°C.
- How is the oscillator frequency programmed in the UC3842BD1?
The oscillator frequency is programmed by connecting resistor RT to Vref and capacitor CT to ground.
- What type of output stage does the UC3842BD1 have?
The UC3842BD1 has a high current totem pole output stage suitable for driving N-Channel MOSFETs.
- What is the start-up current of the UC3842BD1?
The start-up current is less than 0.5mA.
- What are some common applications of the UC3842BD1?
Common applications include off-line power supplies, DC to DC converters, switch-mode power supplies, high-frequency power conversion systems, and power factor correction (PFC) circuits.
