Description:

The L7987 device is a step-down monolithicswitching regulator able to deliver up to 3 A DC.The output voltage adjustability ranges from 0.8 Vto VIN. The wide input voltage range and the100% duty cycle capability meet the fail safespecifications for industrial systems. Theembedded switchover feature on the VBIAS pinmaximizes the efficiency at light load. Theadjustable current limitation, designed to selectthe inductor RMS current accordingly with thenominal output current, and the high switchingfrequency capability make the size of theapplication compact. Pulse-by-pulse currentsensing with digital frequency foldbackimplements an effective constant currentprotection over the different applicationconditions. The peak current foldback decreasesthe stress of the power components in heavyshort-circuit condition. The PGOOD opencollector output can also implement outputvoltage sequencing during the power-up phase.Multiple devices can be synchronized sharing theSYNCH pin to prevent beating noise in low noiseapplications like sensors with A/D conversion.

Features:

 3 A DC output current

 4.5 V to 61 V operating input voltage

 RDS,ON = 250 m typ.

 Adjustable fSW (250 kHz - 1.5 MHz)

 Low IQ-SHD (11 µA typ. from VIN)

 Low IQ (1 mA typ. - VIN 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

Applications:

 Designed for 24 V bus

 Fail safe tolerant system

 Programmable logic controllers (PLCs)