Datasheet LTC3810-5 (Analog Devices) - 9

LTC3810-5
pin FuncTions VON (Pin 2):
On-Time Voltage Input. Voltage trip point
PLL/LPF (Pin 8):
The phase-locked loop’s lowpass filter for the on-time comparator. Tying this pin to the output is tied to this pin. The voltage at this pin defaults to 1.2V voltage or to an external resistive divider from the output when the IC is not synchronized with an external clock at makes the on-time proportional to VOUT. The comparator the MODE/SYNC pin. defaults to 0.7V when the pin is grounded and defaults to
SS/TRACK (Pin 9):
Soft-Start/Tracking Input. For soft-start, 2.4V when the pin is connected to INTVCC. Tie this pin to a capacitor to ground at this pin sets the ramp rate of the INTVCC in high VOUT applications to use a lower RON value. output voltage (approximately 0.6s/µF). For coincident or
VRNG (Pin 3):
Sense Voltage Limit Set. The voltage at this ratiometric tracking, connect this pin to a resistive divider pin sets the nominal sense voltage at maximum output between the voltage to be tracked and ground. current and can be set from 0.5V to 2V by a resistive di-
SHDN (Pin 12):
Shutdown Pin. Pulling this pin below vider from INTVCC. The nominal sense voltage defaults to 1.5V will shut down the LTC3810-5, turn off both of the 95mV when this pin is tied to ground, and 215mV when external MOSFET switches and reduce the quiescent sup- tied to INTVCC. ply current to 240µA.
PGOOD (Pin 4):
Power Good Output. Open-drain logic
UVIN (Pin 13):
UVLO Input. This pin is input to the internal output that is pulled to ground when the output voltage UVLO and is compared to an internal 0.8V reference. An is not between ±10% of the regulation point. The output external resistor divider is connected to this pin and the voltage must be out of regulation for at least 120µs before input supply to program the undervoltage lockout voltage. the power good output is pulled to ground. When UVIN is less than 0.8V, the LTC3810-5 is shut down.
MODE/SYNC (Pin 5):
Pulse Skip Mode Enable/Sync Pin.
NDRV (Pin 14):
Drive Output for External Pass Device of This multifunction pin provides pulse skip mode enable/ the Linear Regulator for INTV disable control and an external clock input to the phase CC. Connect to the gate of an external NMOS pass device and a pull-up resistor to detector. Pulling this pin below 0.8V or to an external the input voltage V logic-level synchronization signal disables pulse skip mode IN. operation and forces continuous operation. Pulling this
EXTVCC (Pin 15):
External Driver Supply Voltage. When pin above 0.8V enables pulse skip mode operation. For a this voltage exceeds 4.7V, an internal switch connects this clock input, the phase-locked loop will force the rising top pin to INTVCC through an LDO and turns off the exter nal gate signal to be synchronized with the rising edge of the MOSFET connected to NDRV, so that controller and gate clock signal.This pin can also be connected to a feedback drive are drawn from EXTVCC. resistor divider from a secondary winding on the inductor
INTV
to regulate a second output voltage.
CC (Pin 16):
Main Supply Pin. All internal circuits ex- cept the output drivers are powered from this pin. INTVCC
ITH (Pin 6):
Error Amplifier Compensation Point and Cur- should be bypassed to ground (Pin 10) with at least a 0.1µF rent Control Threshold. The current comparator threshold capacitor in close proximity to the LTC3810-5. increases with this control voltage. The voltage ranges
DRV
from 0V to 2.6V with 1.2V corresponding to zero sense
CC (Pin 17):
Driver Supply Pin. DRVCC supplies power to the BG output driver. This pin is normally connected to voltage (zero current). INTVCC. DRVCC should be bypassed to BGRTN (Pin 20)
VFB (Pin 7):
Feedback Input. Connect VFB through a resistor with a low ESR (X5R or better) 1µF-10µF capacitor in close divider network to VOUT to set the output voltage. proximity to the LTC3810-5. 38105fd 9 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts