Overview
The L5991D, produced by STMicroelectronics, is a current-mode control PWM controller designed for high-performance switching power supplies. This device is particularly suited for applications requiring high switching frequencies up to 1 MHz and low start-up current. The L5991D features a fully latched PWM logic with double pulse suppression, programmable duty cycle, and a high-current output drive capable of handling power MOSFETs up to 1 A.
The controller includes advanced features such as primary overcurrent fault detection with restart delay, PWM UVLO with hysteresis, and internal 100 ns leading edge blanking of the current sense signal. It also supports standby function, soft start, and synchronization capabilities, making it versatile for various power supply topologies.
Key Specifications
| Parameter | Value | Unit |
|---|---|---|
| VCC Supply Voltage (ICC < 50mA) | Self-limit | V |
| Output Peak Pulse Current | 1.5 A | A |
| Analog Inputs & Outputs (6,7) | -0.3 to 8 V | V |
| Analog Inputs & Outputs (1,2,3,4,5,15,14,13,16) | -0.3 to 6 V | V |
| Power Dissipation @ Tamb = 70°C (DIP16) | 0.83 W | W |
| Power Dissipation @ Tamb = 50°C (SO16) | 0.83 W | W |
| Junction Temperature, Operating Range | -40 to 150 °C | °C |
| Storage Temperature, Operating Range | -55 to 150 °C | °C |
| Thermal Resistance Junction - Ambient (DIP16) | 80 °C/W | °C/W |
| Thermal Resistance Junction - Ambient (SO16) | 120 °C/W | °C/W |
| VREF Output Voltage @ 25°C | 4.925 to 5.075 V | V |
| Start-up Voltage (L5991) | 14 to 15 V | V |
| Minimum Operating Voltage (L5991) | 9 to 11 V | V |
| UVLO Hysteresis (L5991) | 4.5 to 5 V | V |
| Start Up Current Before Turn-on | 40 to 120 µA | µA |
| Operating Current | 9 to 13 mA | mA |
| Quiescent Current (After turn on) | 7 to 10 mA | mA |
| Output Low Voltage @ IO = 250mA | 1 V | V |
| Output High Voltage @ IO = 20mA, VCC = 12V | 10 to 10.5 V | V |
Key Features
- Current-mode control PWM with switching frequency up to 1 MHz
- Low start-up current (< 120 µA)
- High-current output drive suitable for power MOSFET (1 A)
- Fully latched PWM logic with double pulse suppression
- Programmable duty cycle (100% and 50% maximum duty cycle limit)
- Standby function with automatic detection of light load conditions
- Primary overcurrent fault detection with restart delay
- PWM UVLO with hysteresis
- Internal 100 ns leading edge blanking of current sense signal
- Soft start capability
- Synchronization capability for master-slave operation
- Accurate voltage reference (5V ± 1.5%)
- Error amplifier with high gain-bandwidth product and high slew-rate
Applications
- High-performance switching power supplies
- Flyback, forward, and half-bridge converters
- DC-DC converters requiring high switching frequencies
- Power supplies for consumer electronics, industrial equipment, and automotive systems
- Applications requiring low start-up current and high efficiency
Q & A
- What is the maximum switching frequency of the L5991D?
The L5991D can operate at switching frequencies up to 1 MHz.
- What is the start-up current of the L5991D?
The start-up current before turn-on is between 40 to 120 µA.
- What is the output drive capability of the L5991D?
The L5991D has a high-current output drive suitable for power MOSFETs up to 1 A.
- Does the L5991D support synchronization?
Yes, the L5991D supports synchronization for master-slave operation.
- What is the voltage reference output of the L5991D?
The L5991D provides an accurate voltage reference of 5V ± 1.5%.
- How does the standby function work in the L5991D?
The standby function automatically detects light load conditions and decreases the oscillator frequency to minimize power losses.
- What is the thermal resistance junction-ambient for the SO16 package?
The thermal resistance junction-ambient for the SO16 package is 120 °C/W.
- What is the operating current of the L5991D?
The operating current is between 9 to 13 mA.
- Does the L5991D have overcurrent protection?
Yes, the L5991D features primary overcurrent fault detection with restart delay.
- What is the output low voltage of the L5991D at IO = 250mA?
The output low voltage at IO = 250mA is 1 V.
