LD7575 SOP-8 Current-Mode PWM Controller IC
The LD7575 is a Green-Mode, current-mode PWM controller IC designed for offline AC/DC switching power supplies. It integrates a 500 V high-voltage startup circuit, current-mode control, programmable switching frequency, internal slope compensation, leading-edge blanking, VCC over-voltage protection, overload protection, and low-power Green-Mode operation. These features make the LD7575 suitable for compact SMPS, AC/DC adapters, battery chargers, open-frame power supplies, and display power applications.
For Bangladeshi electronics students, engineers, technicians, and DIY power-supply designers, the LD7575 is useful when developing or repairing flyback SMPS circuits and offline AC/DC power supplies.
The LD7575 is a current-mode PWM controller from Leadtrend Technology. Its integrated high-voltage startup circuit can obtain startup current directly from the bulk capacitor, reducing the need for a conventional high-value startup resistor and helping improve startup efficiency. After VCC reaches the UVLO turn-on threshold, the high-voltage startup path is disabled to reduce power loss.
The IC also provides Green-Mode control for reduced standby power consumption, programmable oscillator frequency, current sensing through the CS pin, internal slope compensation, and a gate-drive output capable of driving an external MOSFET.
Features:
- Current-mode PWM control
- SOP-8 package
- 500 V high-voltage startup circuit
- Up to 500 mA gate-drive capability
- Green-Mode power-saving operation
- Non-audible-noise Green-Mode control
- Programmable switching frequency
- Internal slope compensation
- Leading-edge blanking on CS input
- VCC over-voltage protection
- Overload protection
- Under-voltage lockout, UVLO
- Suitable for offline AC/DC power supplies
- Available in SOP-8 and DIP-8 variants
Specifications:
| Parameter | Specification |
|---|---|
| IC | LD7575 |
| Function | Current-Mode PWM Controller |
| Package | SOP-8 |
| Alternative Package | DIP-8 |
| Startup Voltage | High-voltage startup, up to 500 V |
| Gate Drive | 500 mA capability |
| Switching Frequency | Programmable |
| Typical Frequency | 65 kHz at RT = 100 kΩ |
| Green-Mode Frequency | Approximately 20 kHz |
| CS Maximum Input | 0.85 V typical |
| CS Leading-Edge Blanking | 350 ns |
| UVLO ON | 16 V typical |
| UVLO OFF | 10 V typical |
| VCC OVP | 27.5 V typical |
| VCC Absolute Maximum | 30 V |
| HV Pin Maximum | 500 V |
| Operating Ambient Temperature | −40°C to +85°C |
| Junction Temperature | Up to 150°C |
| SOP-8 Power Dissipation | 400 mW at TA = 85°C |
The electrical values above are based on the LD7575 Rev. 04b datasheet; actual limits can vary by parameter, test condition, and device version.
Pin Configuration:
| Pin | Name | Function |
|---|---|---|
| 1 | RT | Sets/programs switching frequency with an external resistor |
| 2 | COMP | Voltage feedback/control-loop input |
| 3 | CS | MOSFET current-sensing input |
| 4 | GND | Ground |
| 5 | OUT | Gate-drive output for external MOSFET |
| 6 | VCC | IC supply voltage |
| 7 | NC | No connection |
| 8 | HV | High-voltage startup input |
The HV pin connects to the positive side of the bulk capacitor for startup, while the OUT pin drives the external power MOSFET.
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