LM5161PWPT

The LM5161 is a 100V, 1A synchronous buck converter with integrated high-side and low-side MOSFETs. The constant on-time control scheme eliminates loop compensation while supporting high step-down ratios with fast transient response. An internal feedback amplifier maintains ±1% output voltage regulation over the full operating temperature range. The on-time is inversely proportional to input voltage, generating an approximately constant switching frequency. A valley current limit circuit provides overload protection. The EN/UVLO circuit independently offers an adjustable input undervoltage threshold and hysteresis. Via its FPWM input pin, the LM5161 can be configured to operate in forced CCM at all load levels, or in DCM under light-load or no-load conditions. When operating in forced CCM, the LM5161 supports multi-output and isolated Fly-Buck applications where low power consumption is a key concern. When programmed for DCM operation, the LM5161 delivers tightly regulated buck output without requiring any external ripple feedback injection circuitry.

Applications

• Industrial programmable logic controllers
• IGBT gate drive bias supply
• Telecom DC/DC primary-side and secondary-side bias
• Electronic energy meters
• Power line communication
• Low-power (<12W) isolated DC-DC (Fly-Buck)

Key features

• 4.5V to 100V wide input voltage range
• Integrated high-side and low-side switches, no Schottky diode required
• 1A maximum load current
• Constant on-time control, no external loop compensation required
• Fast transient response
• Selectable DCM buck operation under light load conditions
• CCM option supports multi-output Fly-Buck
• No external ripple circuit required (when FPWM = 0)
• Near-constant switching frequency, adjustable up to 1MHz
• Programmable soft-start time
• Pre-biased startup
• Peak current limit protection
• Adjustable input UVLO and hysteresis
• ±1% feedback voltage reference
• Thermal shutdown protection
• Use LM5161 with WEBENCH Power Designer to create custom designs