L7987

Voltage Regulators - DC DC Switching Regulators Overview

The L7987 is a 61 V, 3 A asynchronous step-down switching regulator designed for industrial applications. It delivers up to 3 A DC output current with an input voltage range of 4.5 V to 61 V. The device features an adjustable switching frequency from 250 kHz to 1.5 MHz and supports output voltages from 0.8 V to VIN. Key specifications include a typical RDS(ON) of 250 mΩ, low shutdown current of 11 μA, and operation over a temperature range of -40°C to +150°C TJ.

Voltage Regulators - DC DC Switching Regulators Feature Summary

• Embedded VBIAS switchover feature maximizes power conversion efficiency across the entire load range, particularly at light loads.
• Adjustable current limitation allows selection of inductor RMS current corresponding to nominal output current for optimized application design.
• Pulse-by-pulse current sensing with digital frequency foldback implements effective constant current protection under various conditions.
• Multiple devices can be synchronized via the SYNCH pin to prevent beating noise in low-noise applications.

Voltage Regulators - DC DC Switching Regulators Applications

• Industrial systems requiring fail-safe specifications and wide input voltage ranges
• Sensors with A/D conversion requiring low noise through synchronization
• Automotive infotainment systems meeting AEC-Q100 requirements (via A7987 variant)
• Compact power supplies utilizing high switching frequency capabilities

Voltage Regulators - DC DC Switching Regulators Procurement Notes

Verify the specific suffix code on the component marking to confirm exact electrical characteristics, as variants like L7987L differ in current rating. Confirm package type availability, typically HTSSOP-16, and check for automotive qualification if required for your specific application environment. Ensure compatibility with your PCB footprint and thermal management strategy given the synchronous/asynchronous nature of the specific revision.

Voltage Regulators - DC DC Switching Regulators Selection Notes

Select the L7987 when a 3 A output current is required within a 61 V input window. Consider the L7987L variant if a 2 A limit suffices or if specific industrial reliability metrics differ. Evaluate the need for synchronization to reduce input ripple in multi-rail systems. The adjustable frequency allows optimization between efficiency and passive component size.

Voltage Regulators - DC DC Switching Regulators Part Context

The L7987 belongs to STMicroelectronics' family of monolithic buck converters. It is distinct from the L7987L, which is rated for 2 A, and the A7987, which is automotive-qualified. These devices share similar topologies but differ in current handling and qualification standards. They are part of the broader PMIC portfolio designed for robust power management in demanding environments.

Voltage Regulators - DC DC Switching Regulators Replacement Considerations

Public confirmed substitute part numbers are not explicitly listed in the provided documentation. Designers should consult official cross-reference guides or contact STMicroelectronics sales support for verified alternatives that match the 61 V, 3 A asynchronous buck specification.

Voltage Regulators - DC DC Switching Regulators FAQ

How does the L7987 handle short-circuit conditions?

The device uses pulse-by-pulse current sensing with digital frequency foldback to implement constant current protection. Additionally, peak current foldback reduces stress on power components during heavy short-circuit conditions.

Can multiple L7987 regulators be used together?

Yes, multiple devices can be synchronized by sharing the SYNCH pin. This allows them to operate in configurations that prevent beating noise, which is beneficial for low-noise applications like sensors with A/D conversion.

What is the purpose of the PGOOD output?

The PGOOD is an open collector output that indicates power good status. It can also be used to implement output voltage sequencing during the power-up phase of the system.