65-V micro-power buck converters, lowest quiescent current

May 03, 2016 // By Graham Prophet
These 150-mA synchronous DC/DC regulators optimize light-load efficiency for factory automation and automotive applications, and claim the lowest-available quiescent current (IQ) of 10.5 µA; use them TI suggests, for powering sensor applications requiring high efficiency.

The industrial-grade LM5165 and automotive-grade LM5165-Q1 micro-power step-down regulators feature a wide input voltage (VIN) range and dual control modes for optimizing efficiency and printed circuit board (PCB) area. Designs can be carried out in TI's WEBENCH Power Design tool.


The wide 3-V to 65-V operating range enables the LM5165 and LM5165-Q1 micro-power regulators to handle the highest transients in industrial sensor and programmable logic controller (PLC) applications, as well as start-stop and load-dump conditions for 12-V/24-V lead-acid and emerging 48-V lithium-ion automotive batteries. Integrated dual MOSFETs reduce PCB area, while a programmable current-limit scheme reduces inductor size. Both regulators operate at junction temperatures up to 150C for higher temperature environments. The LM5165-Q1 is AEC-Q100 qualified for automotive applications.


The 10.5- µA standby IQ (operating with no load) enables 90% conversion efficiency at 1-mA to 10-mA loads to extend battery life in "always on" applications. (see; Powering smart sensor transmitters in industrial applications )

100% duty cycle enables low-dropout operation, while a P-channel high-side MOSFET eliminates the bootstrap diode and capacitor.

Dual-mode operation: a pulse frequency modulation (PFM) control mode enables the highest efficiency power supply design, while a constant on-time (COT) control mode provides higher output current and better electromagnetic interference (EMI) performance. (see; Simple success with conducted EMI from DC/DC converters .)

Fixed 3.3-V and 5-V options eliminate external feedback resistor dividers to lower bill of materials (BOM).

Programmable current limit optimizes inductor size and cost.


In a 10-pin, 3 x 3-mm VSON, the industrial-grade LM5165 is priced at $1.35 and the automotive-grade LM5165-Q1 is priced at $1.58 (1000). Evaluation modules comprise the COT LM5165EVM-HD-C50X and PFM LM5165EVM-HD-P50A. Download the LM5165 quick-start DC/DC synchronous buck converter design tool and PSPICE transient models .


Texas Instruments; www.ti.com/lm5165-pr