Datasheet LTC3867 (Analog Devices) - 9

LTC3867
PIN FUNCTIONS INTVCC (Pin 16):
Internal 5.3V Regulator Output and
PGOOD (Pin 22):
Power Good Indicator Output. Open- Bottom MOSFET Driver Supply. The control circuits are drain output that pulls to ground when output voltage is powered from this voltage. Decouple this pin to PGND not in regulation. with a minimum of 4.7µF low ESR tantalum or ceramic
MODE/PLLIN (Pin 23):
This is a dual function pin. Tying capacitor. this pin to SGND, INTVCC or floating it enables forced
BG (Pin 17):
Bottom Gate Driver Output. This pin drives continuous mode, pulse-skipping mode or Burst Mode the gate(s) of the bottom N-channel MOSFET(s) between operation respectively. Applying a clock signal to this pin PGND and INTVCC. causes the internal PLL to synchronize the internal oscilla-
PGND (Pin 18):
Power Ground Pin. Connect this pin closely tor to the clock signal and forces forced continuous mode. to the source(s) of the bottom N-channel MOSFET(s), the The PLL compensation network is integrated on to the IC. (–) terminal of CVCC and (–) terminal of CIN.
FREQ (Pin 24):
Frequency Set/Select Pin. A resistor be-
SW (Pin 19):
Switch Node Connection to the Inductor. tween this pin and SGND sets the switching frequency. Voltage swing at this pin is from a Schottky diode (external) This pin sources 20µA. voltage drop below ground to VIN.
SGND (Exposed Pad Pin 25):
Signal Ground. The exposed
TG (Pin 20):
Top Gate Driver Output. This is the output of pad must be soldered to the PCB ground for electrical con- the floating driver with a voltage swing equal to INTV nection and rated thermal performance. All small-signal CC superimposed on the SW voltage. components and compensation components should be connected here. Connect to PGND at one point, close to
BOOST (Pin 21):
Boosted Floating Driver Supply. The (+) the IC. terminal of the bootstrap capacitor connects to this pin. This pin swings from a diode drop below INTVCC up to VIN + INTVCC. 3867f 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Package Description Typical Application Related Parts