ltc3862gn-1 Linear Technology Corporation, ltc3862gn-1 Datasheet - Page 9

• Manufacturer Part Number: ltc3862gn-1
• Description: Multi-phase Current Mode Step-up Dc/dc Controller
• Manufacturer: Linear Technology Corporation

PIN FUNCTIONS
3V8: Output of the Internal 3.8V LDO from INTV
pin for the low voltage analog and digital circuits. A low
ESR 1nF ceramic bypass capacitor should be connected
between 3V8 and SGND, as close as possible to the IC.
BLANK: Blanking Time. Floating this pin provides a nominal
minimum on-time of 290ns. Connecting this pin to 3V8
provides a minimum on-time of 375ns, while connecting
it to SGND provides a minimum on-time of 210ns.
CLKOUT: Digital Output Used for Daisy-Chaining Multiple
LTC3862-1 ICs in Multi-Phase Systems. The PHASEMODE
pin voltage controls the relationship between CH1 and CH2
as well as between CH1 and CLKOUT.
D
mum duty cycle. Floating this pin provides 84% duty cycle.
Connecting this pin to 3V8 provides 75% duty cycle, while
connecting it to SGND provides 96% duty cycle.
FB: Error Amplifi er Input. The FB pin should be connected
through a resistive divider network to V
output voltage.
FREQ: A resistor from FREQ to SGND sets the operating
frequency.
GATE1, GATE2: Gate Drive Output. The LTC3862-1 pro-
vides a 10V gate drive referenced to PGND to drive a high
voltage MOSFET.
INTV
(LDO). A low ESR 4.7μF (X5R or better) ceramic bypass
capacitor should be connected between INTV
as close as possible to the IC.
MAX
CC
: Maximum Duty Cycle.This pin programs the maxi-
: Output of the Internal 10V Low Dropout Regulator
OUT
CC
and PGND,
CC
to set the
. Supply
ITH: Error Amplifi er Output. The current comparator trip
threshold increases with the ITH control voltage. The ITH
pin is also used for compensating the control loop of the
converter.
PGND: Power Ground. Connect this pin close to the
sources of the power MOSFETs. PGND should also be
connected to the negative terminals of V
bypass capacitors. PGND is electrically isolated from the
SGND pin. The Exposed Pad of the QFN and FE packages
is connected to PGND.
PHASEMODE: The PHASEMODE pin voltage programs
the phase relationship between CH1 and CH2 rising gate
signals, as well as the phase relationship between CH1
gate signal and CLKOUT. Floating this pin or connecting
it to either 3V8, or SGND changes the phase relationship
between CH1, CH2 and CLKOUT.
PLLFLTR: PLL Lowpass Filter Input. When synchroniz-
ing to an external clock, this pin serves as the lowpass
fi lter input for the PLL. A series resistor and capacitor
connected from PLLFLTR to SGND compensate the PLL
feedback loop.
RUN: Run Control Input. A voltage above 1.22V on the pin
turns on the IC. Forcing the pin below 1.22V causes the
IC to shut down. There is a 0.5μA pull-up current for this
pin. Once the RUN pin raises above 1.22V, an additional
4.5μA pull-up current is added to the pin for program-
mable hysteresis.
LTC3862-1
IN
and INTV
38621f
9
CC