Datasheet LTC3829 (Analog Devices) - 9

link to page 14 link to page 14 LTC3829
PIN FUNCTIONS (UHF/FE) ISET (Pin 15/Pin 17):
Stage Shedding Comparator and
TG1, TG2, TG3 (Pins 32, 27, 20/Pins 34, 29, 22):
Top Burst Mode Comparator Programming Pin. A resistor to Gate Driver Outputs. These are the outputs of floating ground programs the stage shedding comparator thresh- drivers with a voltage swing equal to INTVCC superim- old or Burst Mode comparator threshold and its current posed on the switch nodes voltages. limit depending on MODE pin setting.
BOOST1, BOOST2, BOOST3 (Pins 33, 26, 19/Pins 35, ILIM (Pin 16/Pin 18):
Current Comparator Sense Voltage
28, 21):
Boosted Floating Driver Supplies. The (+) ter- Range Pin. This pin is to be programmed to SGND, FLOAT minal of the bootstrap capacitors connect to these pins. or INTVCC to set the maximum current sense threshold to These pins swing from a diode voltage drop below INTVCC one of three different levels for each comparator. up to VIN + INTVCC.
PGOOD (Pin 17/Pin 19):
Power Good Indicator Output.
CLKOUT (Pin 34/Pin 36):
Clock Output Pin. CLKOUT is Open-drain logic out that is pulled to ground when the 60° out of phase relative to channel 1 in non-shedding output exceeds ±10% regulation window after the internal mode. During stage shedding, CLKOUT is 180° out of 100µs power bad mask timer expires. phase with channel 1.
PLLIN (Pin 18/Pin 20):
External Synchronization Pin. A
MODE (Pin 35/Pin 37):
Forced Continuous Mode, Burst clock on the pin synchronizes the internal oscillator with Mode or Shed Mode Selection Pin. Connect this pin the clock on this pin. to SGND to force IC in continuous mode of operation.
EXTV
Connect to INTVCC to enable shed mode operation. Leave
CC (Pin 23/Pin 25):
External Power Input to an Internal Switch Connected to INTV the pin floating to enable Burst Mode operation. CC. This switch closes and supplies the IC power, bypassing the internal low
IFAST (Pin 36/Pin 38):
Programmable Pin for Nonlinear dropout regulator, whenever EXTVCC is higher than 4.7V. Control Trip Threshold. A resistor to ground programs the Do not exceed 6V on this pin and ensure VIN > VEXTVCC tripping threshold for nonlinear control circuit. Connect at all times. this pin to INTVCC to disable this feature. See Applications
INTV
Information section for details. Leave this pin floating
CC (Pin 24/Pin 26):
Internal 5V Regulator Output. The control circuits are powered from this voltage. Decouple when it is not used. this pin to PGND with a minimum of 4.7µF low ESR tan-
ITEMP (Pin 37/Pin 1):
Input of the Temperature Sensing talum or ceramic capacitor. Comparator. Connect this pin to external NTC resistors
V
placed near inductors.
IN (Pin 25/Pin 27):
Main Input Supply. Decouple this pin to PGND with a capacitor (0.1µF to 1µF).
DIFFOUT (Pin 38/Pin 2):
Output of Remote Sensing
BG1, BG2, BG3 (Pins 30, 29, 22/Pins 32, 31, 24):
Bottom Differential Amplifier. Connect this pin to VFB through a Gate Driver Outputs. These pins drive the gates of the bot- resistive divider. tom N-channel MOSFETs between PGND and INTVCC.
SGND/PGND (Exposed Pad Pin 39/Exposed Pad Pin SW1, SW2, SW3 (Pins 31, 28, 21/Pins 33, 30, 23): 39):
Combined Signal and Power Ground Pad. Connect Switch Node Connections to Inductors. Voltage swing this pad closely to the sources of the bottom N-channel at these pins is from a Schottky diode (external) voltage MOSFETs, the (–) terminal of CVCC and the (–) terminal drop below ground to V of CIN. All small-signal components and compensation IN. components should also Kelvin-connect to this pad. Rev. E For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Application Package Description Revision History Typical Application Related Parts