SNVS397F September 2005 – December 2025 LM5005
PRODUCTION DATA
The LM5005 contains a unique current monitoring scheme for control and overcurrent protection. When set correctly, the emulated current sense signal provides a signal that is proportional to the buck switch current with a scale factor of 0.5V/A. The emulated ramp signal is applied to the current limit comparator. If the emulated ramp signal exceeds 1.75V (3.5A), the present cycle terminates (cycle-by-cycle current limiting). In applications with small output inductance and high input voltage, the switch current can overshoot due to the propagation delay of the current limit comparator. If an overshoot must occur, the diode current sampling circuit detects the excess inductor current during the off-time of the buck switch. If the sample-and-hold DC level exceeds the 1.75V current limit threshold, the buck switch is disabled and skips pulses until the diode current sampling circuit detects that the inductor current is decayed below the current limit threshold. This approach prevents current runaway conditions due to propagation delays or inductor saturation, because the inductor current is forced to decay following any current overshoot.