LTC3788_15 Datasheet, PDF (10/32 Pages) Linear Technology – 2-Phase, Dual Output Synchronous Boost Controller

LTC3788
Pin Functions
PGOOD2 (Pin 14): Power Good Indicator for Channel 2.
Open-drain logic output that is pulled to ground when
the output voltage is more than ±10% away from the
regulated output voltage. To avoid false trips the output
voltage must be outside the range for 25µs before this
output is activated.
INTV_CC (Pin 19): Output of Internal 5.4V LDO. Power
supply for control circuits and gate drives. Decouple this
pin to GND with a minimum 4.7µF low ESR tantalum or
ceramic capacitor.
EXTV_CC (Pin 20): External Power Input. When this pin is
higher than 4.8V an internal switch bypasses the internal
regulator and supply power to INTV_CC directly from EXTV_CC.
PGND (Pin 21): Driver Power Ground. Connects to the
sources of bottom (main) N-channel MOSFETs and the
(–) terminal(s) of C_IN and C_OUT.
VBIAS (Pin 22): Main Supply Pin. It is normally tied to the
input supply V_IN or to the output of the boost converter.
A bypass capacitor should be tied between this pin and
the signal ground pin. The operating voltage range on this
pin is 4.5V to 38V (40V abs max).
BG1, BG2 (Pin 23, Pin 18): Bottom Gate. Connect to the
gate of the main NMOS.
BOOST1, BOOST2 (Pin 24, Pin 17): Floating power supply
for the synchronous NMOS. Bypass to SW with a capacitor
and supply with a Schottky diode connected to INTV_CC.
TG1, TG2 (Pin 25, Pin 16): Top Gate. Connect to the gate
of the synchronous NMOS.
SW1, SW2 (Pin 26, Pin 15): Switch Node. Connect to the
source of the synchronous NMOS, the drain of the main
NMOS and the inductor.
PGOOD1 (Pin 27): Power Good Indicator for Channel 1.
Open-drain logic output that is pulled to ground when
the output voltage is more than ±10% away from the
regulated output voltage. To avoid false trips the output
voltage must be outside the range for 25µs before this
output is activated.
ILIM (Pin 28): Current Comparator Sense Voltage Range
Input. This pin is used to set the peak current sense volt-
age in the current comparator. Connect this pin to SGND,
open and INTV_CC to set the peak current sense voltage to
50mV, 75mV, and 100mV, respectively.
SS1, SS2 (Pin 29, Pin 13): Output Soft-Start Input. A
capacitor to ground at this pin sets the ramp rate of the
output voltage during start-up.
ITH1, ITH2 (Pin 30, Pin 12): Current Control Threshold
and Error Amplifier Compensation Point. The voltage on
this pin sets the current trip threshold.
VFB1, VFB2 (Pin 31, Pin 11): Error Amplifier Feedback
Input. This pin receives the remotely sensed feedback
voltage from an external resistive divider connected across
the output.
SENSE1⁺, SENSE2⁺ (Pin 32, Pin 10): Positive Current
Sense Comparator Input. The (+) input to the current
comparator is normally connected to the positive terminal
of a current sense resistor. The current sense resistor
is normally placed at the input of the boost controller in
series with the inductor. This pin also supplies power to
the current comparator.
GND (Exposed Pad Pin 33): Ground. The exposed pad
must be soldered to the circuit board for rated thermal
performance.
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