KA3842 Current-Mode PWM Controller IC DIP-8
The KA3842 is a high-performance current-mode PWM controller IC designed for off-line and DC-DC converter applications that require high efficiency, precision control, and fast response. It operates as a fixed-frequency controller and provides all the essential functions needed for implementing reliable and cost-effective switch-mode power supplies (SMPS). With a wide operating voltage range of 7.6 V to 30 V and a precision 5.0 V reference, the KA3842 delivers stable operation across a variety of input conditions.
Featuring a high-speed totem-pole output, the KA3842 can directly drive power MOSFETs or BJTs with peak currents up to 1 A, ensuring efficient switching and reduced power losses. Its current-mode control architecture provides superior line and load regulation, automatic pulse-by-pulse current limiting, and inherent cycle-by-cycle overcurrent protection.
The KA3842 includes undervoltage lockout (UVLO) with typical start and stop thresholds of 16 V and 10 V, making it particularly well suited for off-line (AC-to-DC) power supplies and continuous conduction mode designs. Housed in a compact DIP-8 package, it offers a cost-effective solution for applications such as industrial power supplies, motor drivers, and battery chargers that demand robust, efficient PWM control.
Features
- Wide Operating Voltage Range: 7.6 V to 30 V.
- Precision 5.0 V Reference: ±2% tolerance for accurate regulation.
- Fixed-Frequency Operation: Up to 500 kHz (set by external RT/CT).
- Current-Mode Control: Provides superior line and load regulation with cycle-by-cycle current limiting.
- High-Speed Totem-Pole Output: ±1 A peak drive capability for direct MOSFET or transistor control.
- Low Start-Up Current: Less than 0.5 mA for high-efficiency standby operation.
- Undervoltage Lockout (UVLO): Start-up at 16 V, turn-off at 10 V for off-line power applications.
- Built-In Soft-Start and Leading-Edge Blanking: Enhances system stability and noise immunity.
- Thermal Stability: Ensures consistent performance over temperature range.
- Standard 8-Pin DIP/SOP Package: Simplifies design integration and PCB layout.
Pinout Configuration
| Pin No. | Symbol | Name / Function |
|---|---|---|
| 1 | COMP | Compensation input – error amplifier output used for loop compensation |
| 2 | VFB | Feedback input – voltage feedback to the internal error amplifier |
| 3 | ISENSE | Current sense input – monitors switch current for current-mode control and protection |
| 4 | RT/CT | Oscillator timing resistor/capacitor – sets the switching frequency |
| 5 | GND | Ground reference for all signals |
| 6 | OUTPUT | Output drive pin – to drive an external MOSFET or transistor |
| 7 | VCC | Supply voltage input (operating range: 7.6 V – 30 V) |
| 8 | VREF | 5 V reference output (can source up to 20 mA for biasing) |
Dimensions
Specifications
| Parameter | Descriptions |
| Product Type | Current-Mode PWM Control IC |
| Part Number | KA3842A |
| Datasheet | KA3842 |
| Package Type | DIP-8 |
| Operating Voltage Range | 7.6 V – 30 V |
| Reference Voltage | 5.0 V ±2% |
| Oscillation Frequency | 500 kHz |
| Output Type | Adjustable |
| Topology Supported | Buck, Boost, Flyback, Forward |
| Number of Channels | 1 |
| Switch Type | External MOSFET required |
| Undervoltage Lockout (UVLO) | 16V (start) – 10V (stop) |
| Output Drive Capability | ±1 A peak |
| Optimization | General-purpose PWM control, suitable for wide duty cycle designs |
| Maximum Duty Cycle | 100% |
| UVLO Thresholds (Start/Stop) | Slightly higher thresholds |
| Design Flexibility | Allows full-range duty cycles for continuous conduction designs |
| Control Method | Fixed-frequency peak current-mode PWM |
| Main Application | Off-line SMPS / AC-DC converter, High-Voltage Converters, Continuous Flyback |
| Operating Temperature Range | 0 °C – +70 °C |
Applications
- Switch-Mode Power Supplies (SMPS).
- DC-DC Converter Circuits.
- Battery Chargers and Power Adapters.
- LED Drivers and Lighting Power Supplies.
- Motor Speed Control Systems.
- Inverter and Converter Modules.
- Industrial and Consumer Power Electronics.
- Offline Flyback and Forward Converter Designs.
Package Contents
- 1 x KA3842 Current-Mode PWM Controller IC DIP-8