Datasheet LTC3422 (Analog Devices) - 10

LTC3422
U OPERATIO Simplified Diagram of Automatic Burst Mode Control Circuit
VCC UVLO IOUT 2mA COMP 10,000 VREF – 4% + – BURST COMP – + 880mV TO FB 1.16V 6 SSDONE 0 = PWM MODE 1 = Burst Mode OPERATION ERROR AMP/ SLEEP COMP BURST – SLEEP V + REF ±1% COMP CLAMP 500mV TO 1V VC BURST 7 3 CC1 R C B B RZ 3422 AI01 BURST must be able to sink up to 4mA. Burst Mode still commanding this by grounding BURST ) and the cycle operation is inhibited during soft-start. will repeat, resulting in about 4% output ripple. The If V maximum average current that can be supplied in Burst IN is greater than VOUT – 300mV, the part will exit Burst Mode operation and the synchronous rectifier will be Mode operation is given by: disabled. • V I IN = 275 n i mA Note that if the load current applied during forced Burst OUT MAX ( ) VOUT Mode operation (BURST is grounded) exceeds the current that can be supplied, the output voltage will start to droop
Output Disconnect and Inrush Current Limiting
and the LTC3422 will automatically come out of Burst The LTC3422 is designed to allow true output disconnect Mode operation and enter fixed frequency mode, raising by eliminating body diode conduction of the internal VOUT. Once regulation is achieved, the LTC3422 will then P-channel MOSFET rectifier. This allows VOUT to go to zero enter Burst Mode operation once again (since the user is volts during shutdown without drawing any current from 3422fa 10