Features • Wide 4.5V to 42V 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 0.9V • Precision ±2% feedback reference • Capable of 100% duty cycle operation • Internal soft-start timer • Integrated high voltage bias regulator • Thermal shutdown Description The LM25085A is a functional variant of the LM25085 COT PFET Buck Switching Controller. The functional differences of the LM25085A are: The feedback reference voltage is 0.9V, the forced off-time after current limit detection is longer, and the soft-start time is shorter (1.8 ms). The LM25085A 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 42V 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.

LM25085A   4.50 <= V in Lower  V   <= V in Upper  V   <= 42.00 V out 0.90 <=  V <= 42.00 I out    A <= 10.00 Ambient Temperature  °C <= 100 What are WEBENCH® tools? Also Recommended LM25085▲ 1.25V Reference Voltage LM5085▲ Higher VIN Up To 75V 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
	LM25085A 42V Constant On-Time PFET Buck Switching Controller with 0.9V Reference	507 Kbytes	16-Mar-09

Featured Application Notes

Title		Size	Date	Other Language
	AN-1933: Application Note 1933 LM25085A Evaluation Board	786 Kbytes	26-Feb-09

More Application Notes

Title		Size	Date	Other Language
	AN-1931: Application Note 1931 LM25088 Evaluation Board	242 Kbytes	8-Dec-08

Design Tools

Title	Size	Date
LM25085A Quick Start Calculator	423 Kbytes	29-May-2009

Reliability Metrics

Part Number	Process	EFR Reject	EFR Sample Size	PPM	LTA Rejects	LTA Device Hours	FITS	MTTF (Hours)
LM25085AMM	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085AMME	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085AMMX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085AMY	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085AMYE	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085AMYX	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085ASD	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085ASDE	ABCD150XV1	0	3868	0	0	2595000	2	736338335
LM25085ASDX	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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