Datasheet LT3581 (Analog Devices) - 9

LT3581
STATE DIAGRAM
SHDN < 1.33V (TYPICAL) or VIN < 2.3V (TYPICAL) CHIP OFF • ALL SWITCHES DISABLED • IGATE OFF • FAULTS CLEARED SHDN > 1.33V (TYPICAL) AND VIN > 2.3V (TYPICAL) INITIALIZE • SS PULLED LOW FAULT1 FAULT2 FAULT DETECTED SS < 50mV • SS CHARGES UP • IGATE OFF • FAULT PIN PULLED LOW SOFT START INTERNALLY BY LT3581 FAULT1 • IGATE ENABLED • SWITCHER DISABLED • SS CHARGES UP • CLKOUT DISABLED • SWITCHER ENABLED SS > 1.8V AND NO FAULT1 CONDITIONS STILL DETECTED POST FAULT DELAY SAMPLE MODE • SS SLOWLY DISCHARGES FAULT1 • Q1 & Q2 SWITCHES FORCED ON EVERY CYCLE FOR AT LEAST MINIMUM FAULT1 ON TIME SS < 50mV • IGATE FULLY ACTIVATED WHEN SS > 500mV LOCAL FAULT OVER • INTERNAL FAULT PIN PULLDOWN FAULT1 RELEASED BY LT3581 • SS CONTINUES DISCHARGING IF |VOUT| DROPS CAUSING: TO GND FB < 1.17V (BOOST) NORMAL MODE OR FAULT PIN > 1.0V FB > 45mV (INVERTING) • NORMAL OPERATION FAULT1 • CLKOUT ENABLED WHEN SS > 1.8V FAULT1 = OVER VOLTAGE PROTECTION ON VIN (VIN > 22V MIN) OVER TEMPERATURE (TJUNCTION > 165°C) OVER CURRENT ON SW1 (ISW1 > 1.9A MIN) OVER VOLTAGE PROTECTION ON SW1 (VSW1 > 42V MIN) OVER VOLTAGE PROTECTION ON SW2 (VSW2 > 42V MIN) FAULT2 = FAULT PULLED LOW EXTERNALLY (FAULT < 0.75V) 3581 SD
Figure 2. State Diagram
3581fb For more information www.linear.com/LT3581 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram State Diagram Operation Applications Information Appendix Typical Applications Typical Application Related Parts