Features • Wide 4.5V to 75V input voltage range • Adjustable current limit using RDS(ON) or a current sense resistor • Programmable switching frequency to 1MHz • No loop compensation required • Ultra-Fast transient response • Nearly constant operating frequency with line and load variations • Adjustable output voltage from 1.25V • Precision ±2% feedback reference • Capable of 100% duty cycle operation • Internal soft-start timer • Integrated high voltage bias regulator • Thermal shutdown Description The LM5085 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, efficient buck regulator for a wide range of applications. This high voltage controller contains a PFET gate driver and a high voltage bias regulator which operates over a wide 4.5V to 75V input range. The constant on-time regulation principle requires no loop compensation, simplifies circuit implementation, and results in ultra-fast load transient response. The operating frequency remains nearly constant with line and load variations due to the inverse relationship between the input voltage and the on-time. The PFET architecture allows 100% duty cycle operation for a low dropout voltage. Either the RDS(ON) of the PFET or an external sense resistor can be used to sense current for over-current detection.

LM5085   4.50 <= V in Lower  V   <= V in Upper  V   <= 75.00 V out 1.25 <=  V <= 75.00 I out    A <= 10.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools? Also Recommended LM25085▲ VIN 4.5V To 42V LM25085A▲ VIN 4.5V To 42V And Lower 0.9V Reference Voltage MY BRIEFCASE                                       Click any "Briefcase" icon to add an item

Typical Application click for larger image	Block Diagram click for larger image
Typical Performance *click for larger image

Datasheet

Title		Size	Date	Other Language
	LM5085 75V Constant On-Time PFET Buck Switching Controller	465 Kbytes	6-Feb-09

Featured Application Notes

Title		Size	Date	Other Language
	AN-1878: Application Note 1878 LM5085 Evaluation Board	359 Kbytes	13-Nov-08

More Application Notes

Title		Size	Date	Other Language
	AN-1474: Application Note 1474 The LM507X Family of PoE Devices: Frequently Asked Questions (FAQs)	457 Kbytes	10-May-06	中文
	AN-1455: Application Note 1455 LM5072 Evaluation Board	708 Kbytes	30-Mar-06	中文
	AN-1430: Application Note 1430 LM5071 Evaluation Board	738 Kbytes	4-Jan-06
	AN-1358: Application Note 1358 LM5070 'AE' Evaluation Board	787 Kbytes	27-Jan-05
	AN-1408: Application Note 1408 Designing Power Over Ethernet Using LM5070 and DP83865	1072 Kbytes	10-Jan-06	中文
	AN-1521: Application Note 1521 POEPHYTEREV-I / -E User Guide	14913 Kbytes	4-Apr-08
	AN-1346: Application Note 1346 LM5070 'HE' Evaluation Board	550 Kbytes	13-Mar-06	中文

Design Tools

Title	Size	Date
LM(2)5085 Quick Start Calculator	425 Kbytes	3-Jun-2009

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM5085MM	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085MME	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085MMX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085MY	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085MYE	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085MYX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085QMY	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085QMYE	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085QMYX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085SD	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085SDE	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM5085SDX	ABCD150XV1	0	3868	0	0	2595000	2	736338335

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

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