LM2650 Datasheet | National Semiconductor

Description The LM2650 is a step-down DC/DC converter featuring high efficiency over a 3A to milliamperes load range. This feature makes the LM2650 an ideal fit in battery-powered applications that demand long battery life in both run and standby modes. The LM2650 also features a logic-controlled shutdown mode in which it draws at most 25µA from the input power supply. The LM2650 employs a fixed-frequency pulse-width modulation (PWM) and synchronous rectification to achieve very high efficiencies. In many applications, efficiencies reach 95%+ for loads around 1A and exceed 90% for moderate to heavy loads from 0.2A to 2A. A low-power hysteretic or ″sleep″ mode keeps efficiencies high at light loads. The LM2650 enters and exits sleep mode automatically as the load crosses ″sleep in″ and ″sleep out″ thresholds. The LM2650 provides nodes for programming both thresholds via external resistors. A logic input allows the user to override the automatic sleep feature and keep the LM2650 in PWM mode regardless of the load level. An optional soft-start feature limits current surges from the input power supply at start up and provides a simple means of sequencing multiple power supplies. Features n n n n n n n n n n n n n Ultra high efficiencies (95% possible) High efficiency over a 3A to milliamperes load range Synchronous switching of internal NMOS power FETs Wide input voltage range (4.5V to 18V) Output voltage adjustable from 1.5V to 16V Automatic low-power sleep mode Logic-controlled micropower shutdown (IQSD ≤ 25 µA) Frequency adjustable up to 300 k Hz Frequency synchronization with external signal Programmable soft-start Short-circuit current limiting Thermal shutdown Available in 24-lead Small-Outline package Applications n n n n n n Notebook and palmtop personal puters Portable data terminals Modems Portable Instruments Global positioning devices (GPSs) Battery-powered digital devices Typical Application LM2650-ADJ Efficiency DS012848-2 DS012848-1 Converting a...