LTC3810EG LINER [Linear Technology], LTC3810EG Datasheet - Page 9

• Manufacturer Part Number: LTC3810EG
• Description: 100V Current Mode Synchronous Switching Regulator Controller
• Manufacturer: LINER [Linear Technology]

PIN FUNCTIONS
I
to this pin to set the one-shot timer current and thereby
set the switching frequency.
V
the on-time comparator. Tying this pin to the output voltage
or an external resistive divider from the output makes the
on-time proportional to V
0.7V when the pin is grounded and defaults to 2.4V when
the pin is connected to INTV
high V
V
pin sets the nominal sense voltage at maximum output
current and can be set from 0.5V to 2V by a resistive
divider from INTV
to 95mV when this pin is tied to ground, and 215mV when
tied to INTV
PGOOD (Pin 6): Power Good Output. Open-drain logic
output that is pulled to ground when the output voltage
is not between ±10% of the regulation point. The output
voltage must be out of regulation for at least 120μs before
the power good output is pulled to ground.
MODE/SYNC (Pin 7): Pulse Skip Mode Enable/Sync Pin.
This multifunction pin provides pulse skip mode enable/
disable control and an external clock input to the phase
detector. Pulling this pin below 0.8V or to an external
logic-level synchronization signal disables pulse skip mode
operation and forces continuous operation. Pulling this
pin above 0.8V enables pulse skip mode operation. For a
clock input, the phase-locked loop will force the rising top
gate signal to be synchronized with the rising edge of the
clock signal.This pin can also be connected to a feedback
resistor divider from a secondary winding on the inductor
to regulate a second output voltage.
I
rent Control Threshold. The current comparator threshold
increases with control voltage. The voltage ranges from
0V to 2.6V with 1.2V corresponding to zero sense voltage
(zero current).
V
divider network to V
ON
TH
FB
ON
RNG
(Pin 8): Error Amplifi er Compensation Point and Cur-
(Pin 1): On-Time Current Input. Tie a resistor from V
(Pin 9): Feedback Input. Connect V
(Pin 4): On-Time Voltage Input. Voltage trip point for
(Pin 5): Sense Voltage Limit Set. The voltage at this
OUT
applications to use a lower R
CC
.
CC
. The nominal sense voltage defaults
OUT
to set the output voltage.
OUT
. The comparator defaults to
CC
. Tie this pin to INTV
FB
through a resistor
ON
value.
CC
IN
in
PLL/LPF (Pin 10): The phase-locked loop’s lowpass fi lter
is tied to this pin. The voltage at this pin defaults to 1.2V
when the IC is not synchronized with an external clock at
the MODE/SYNC pin.
SS/TRACK (Pin 11): Soft-Start/Tracking Input. For soft-
start, a capacitor to ground at this pin sets the ramp rate of
the output voltage (approximately 0.6s/μF). For coincident
or ratiometric tracking, connect this pin to a resistive divider
between the voltage to be tracked and ground.
SGND (Pin 12): Signal Ground. All small-signal compo-
nents should connect to this ground and eventually connect
to PGND at one point.
SHDN (Pin 13): Shutdown Pin. Pulling this pin below 1.5V
will shut down the LTC3810, turn off both of the external
MOSFET switches and reduce the quiescent supply cur-
rent to 240μA.
UVIN (Pin 14): UVLO Input. This pin is input to the internal
UVLO and is compared to an internal 0.8V reference. An
external resistor divider is connected to this pin and the
input supply to program the undervoltage lockout voltage.
When UVIN is less than 0.8V, the LTC3810 is shut down.
NDRV (Pin 15): Drive Output for External Pass Device of
the Linear Regulator for INTV
an external NMOS pass device and a pull-up resistor to
the input voltage V
EXTV
this voltage exceeds 6.7V, an internal switch connects
this pin to INTV
nal MOSFET connected to NDRV, so that controller and
gate drive are drawn from EXTV
INTV
except the output drivers are powered from this pin.
INTV
least a 0.1μF capacitor in close proximity to the LTC3810.
DRV
to the BG output driver. This pin is normally connected to
INTV
with a low ESR (X5R or better) 1μF capacitor in close
proximity to the LTC3810.
CC
CC
CC
CC
CC
(Pin 18): Driver Supply Pin. DRV
. DRV
(Pin 17): Main Supply Pin. All internal circuits
should be bypassed to ground (Pin 10) with at
(Pin 16): External Driver Supply Voltage. When
CC
CC
should be bypassed to BGRTN (Pin 20)
through an LDO and turns off the exter-
IN
.
CC
CC
. Connect to the gate of
.
CC
LTC3810
supplies power
3810fb
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