General Description
The MIC2172 and MIC3172 are complete 100kHz SMPS current-mode controllers with internal 65V 1.25A power switches. The MIC2172 features external frequency synchronization or frequency adjustment, while the MIC3172 features an enable/shutdown control input.
Although primarily intended for voltage step-up applications, the floating switch architecture of the MIC2172/3172 makes it practical for step-down, inverting, and Cuk configurations as well as isolated topologies.

FEATUREs
• 1.25A, 65V internal switch rating
• 3V to 40V input voltage range
• Current-mode operation
• Internal cycle-by-cycle current limit
• Thermal shutdown
• Low external parts count
• Operates in most switching topologies
• 7mA quiescent current (operating)
• <1µA quiescent current, shutdown mode (MIC3172)
• TTL shutdown compatibility (MIC3172)
• External frequency synchronization (MIC2172)
• External frequency trim (MIC2172)
• Fits most LT1172 sockets (see applications info)

APPLICATIONs
• Laptop/palmtop computers
• Toys
• Hand-held instruments
• Off-line converter up to 50W (requires external power switch)
• Predriver for higher power capability
• Master/slave configurations (MIC2172)