LM5165YDRCR

The LM5165YDRCR from Texas Instruments is a 150mA synchronous buck converter in a tiny SOT-23-6 package supporting 4.5V to 65V input. Using constant on-time (COT) control with integrated high-side and low-side MOSFETs, it requires no external compensation components. The 13uA standby quiescent current extends battery life in always-on applications. The adaptive on-time maintains near-constant switching frequency while providing excellent transient response. Internal soft-start prevents inrush current, and cycle-by-cycle current limit provides robust overload protection. The device is ideal for high-voltage industrial bus to low-voltage POL conversion.

The LM5165YDRCR uses constant on-time (COT) control, a hysteretic-derived topology where the high-side MOSFET is turned on for a fixed on-time when the output voltage drops below the regulation threshold. The on-time is proportional to VOUT/VIN to maintain approximately constant switching frequency. During the on-time, current flows from VIN through the inductor to VOUT. When the on-time expires, the high-side MOSFET turns off and the low-side MOSFET turns on, allowing inductor current to freewheel. When the output voltage again drops below the threshold, the cycle repeats. In Eco-mode at light loads, the low-side MOSFET turns off when inductor current reaches zero, enabling discontinuous conduction mode (DCM) with higher efficiency.

• 24V/48V industrial bus to 3.3V/5V POL conversion
• Building automation HVAC sensor power supply
• Telecom -48V bus to low-voltage regulation
• Battery-powered field instrumentation
• Automotive 12V/24V auxiliary power rails