L7987TR

The L7987 device is a step-down monolithic switching regulator able to deliver up to 3 A DC. The output voltage adjustability ranges from 0.8 V to VIN. The wide input voltage range and the 100% duty cycle capability meet the fail safe specifications for industrial systems. The embedded switchover feature on the VB IAS pin maximizes the efficiency at light load. The adjustable current limitation, designed to select the inductor RMS current accordingly with the nominal output current, and the high switching frequency capability make the size of the application compact. Pulse-by-pulse current sensing with digital frequency foldback implements an effective constant current protection over the different application conditions. The peak current foldback decreases the stress of the power components in heavy short-circuit condition. The PGOOD open collector output can also implement output voltage sequencing during the power-up phase. Multiple devices can be synchronized sharing the SYNCH pin to prevent beating noise in low noise applications like sensors with A/D conversion.

Applications

• Designed for 24 V bus
• Fail safe tolerant system
• Programmable logic controllers (PLCs)

Key features

• 3 A DC output current
• 4.5 V to 61 V operating input voltage
• RDS,ON = 250 mΩ typ.
• Adjustable fSW (250 kHz – 1.5 MHz)
• Low IQ-SHD (11 μA typ. from VIN)
• Low IQ (1 mA typ. - ΔVIN 24 V - VOUT 3.3 V)
• Output voltage adjustable from 0.8 V to VIN
• Synchronization
• Adjustable soft-start time
• Adjustable current limitation
• Low dropout operation (12 μs max.)
• VBIAS improves efficiency at light load
• PGOOD open collector output
• Output voltage sequencing
• Digital frequency foldback in short-circuit
• Peak current foldback in short-circuit
• Auto-recovery thermal shutdown