Datasheet LT3480 (Analog Devices) - 7

LT3480
TYPICAL PERFORMANCE CHARACTERISTICS Switching Waveforms; Transition Switching Waveforms; Full from Burst Mode to Full Frequency Frequency Continuous Operation
VSW VSW 5V/DIV 5V/DIV IL IL 0.2A/DIV 0.5A/DIV VOUT VOUT 10mV/DIV 10mV/DIV 3480 G25 1µs/DIV 3480 G26 1µs/DIV VIN = 12V; FRONT PAGE APPLICATION VIN = 12V; FRONT PAGE APPLICATION ILOAD = 110mA ILOAD = 1A
PIN FUNCTIONS BD (Pin 1):
This pin connects to the anode of the boost
SYNC (Pin 6):
This is the external clock synchronization Schottky diode. BD also supplies current to the internal input. Ground this pin for low ripple Burst Mode operation at regulator. BD must be locally bypassed when not tied to low output loads. Tie to a clock source for synchronization. VOUT with a low ESR capacitor (1µF). Clock edges should have rise and fall times faster than 1µs.
BOOST (Pin 2):
This pin is used to provide a drive See synchronizing section in Applications Information. voltage, higher than the input voltage, to the internal bipolar
PG (Pin 7):
The PG pin is the open collector output of an NPN power switch. internal comparator. PG remains low until the FB pin is
SW (Pin 3):
The SW pin is the output of the internal power within 14% of the final regulation voltage. PG output is switch. Connect this pin to the inductor, catch diode and valid when VIN is above 3.6V and RUN/SS is high. boost capacitor.
FB (Pin 8):
The LT3480 regulates the FB pin to 0.790V.
V
Connect the feedback resistor divider tap to this pin.
IN (Pin 4):
The VIN pin supplies current to the LT3480’s internal regulator and to the internal power switch. This
VC (Pin 9):
The VC pin is the output of the internal error pin must be locally bypassed. amplifier. The voltage on this pin controls the peak switch
RUN/SS (Pin 5):
The RUN/SS pin is used to put the current. Tie an RC network from this pin to ground to LT3480 in shutdown mode. Tie to ground to shut down compensate the control loop. the LT3480. Tie to 2.5V or more for normal operation. If
RT (Pin 10):
Oscillator Resistor Input. Connecting a resistor the shutdown feature is not used, tie this pin to the VIN to ground from this pin sets the switching frequency. pin. RUN/SS also provides a soft-start function; see the
Exposed Pad (Pin 11):
Ground. The exposed pad must Applications Information section. be soldered to PCB. 3480fe For more information www.linear.com/LT3480 7 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts