PM6681A

Overview

The PM6681A is a dual synchronous step-down controller with an adjustable LDO, designed for high-efficiency conversion using lossless current sensing. It features a constant on-time architecture for fast transient response and embedded voltage feed-forward for nearly constant switching frequency. The device supports selectable pulse skipping at light loads and includes output voltage ripple compensation. Input voltage ranges from 6V to 36V. Output voltages OUT1 and OUT2 are adjustable from 0.9V to 5V and 0.9V to 3.3V respectively. It integrates two LDOs: a fixed 5V and an adjustable 0.9V-3.3V LDO, both delivering 100mA peak current. A 1.237V ±1% reference voltage is available.

Feature Summary

• Dual synchronous step-down control with lossless current sensing technique
• Constant on-time architecture ensuring fast load transient response
• Embedded integrator control loop compensates DC voltage error due to output ripple
• Selectable pulse skipping technique increases efficiency at very light loads

Applications

• Notebook PC chipset power supply design
• High-efficiency dual rail power conversion systems
• Applications requiring audio noise avoidance via minimum switching frequency selection

Procurement Notes

Verify the specific ordering suffix against the manufacturer's official documentation to confirm package type, tape/reel specifications, and temperature grade. Ensure the selected variant matches the required input voltage range and output configuration. Cross-reference the part number with the latest datasheet revision to confirm pinout compatibility and electrical characteristics before finalizing procurement orders.

Selection Notes

Select this component when designing dual-output buck converters requiring integrated LDOs for auxiliary rails. The PM6681A is suitable for applications needing high efficiency across varying load conditions, particularly where light-load performance is critical. Consider the 6V to 36V input range and the specific output voltage adjustment limits for OUT1 and OUT2 when defining the power stage requirements.

Part Context

The PM6681A belongs to the PM6680A series of power management ICs from STMicroelectronics. It shares architectural similarities with the PM6680 but offers extended input voltage capabilities up to 36V compared to the 28V limit in some related variants. This family targets notebook and portable electronics applications requiring compact, efficient power solutions.

Replacement Considerations

PM6680 is a related dual step-down controller within the same product family, though it may have different input voltage specifications.