LTC3611 Ver la hoja de datos (PDF) - Linear Technology

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LTC3611

10A, 32V Monolithic Synchronous Step-Down DC/DC Converter

Linear Technology 

LTC3611

PIN FUNCTIONS

PGND (Pins 1, 2, 3, 56, 57, 58, 59, 60, 61, 62, 63, 64,

65): Power Ground. Connect this pin closely to the (–)

terminal of CVCC and the (–) terminal of CIN.

SW (Pins 4, 5, 6, 7, 8, 9, 10, 11, 26, 55, 66): Switch

Node Connection to the Inductor. The (–) terminal of the

bootstrap capacitor CB also connects here. This pin swings

from a diode voltage drop below ground up to VIN.

PVIN (Pins 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22,

23, 24, 25, 67): Main Input Supply. Decouple this pin to

power PGND with the input capacitance CIN.

NC (Pin 27): No Connection.

SGND (Pins 28, 31, 32, 33, 34, 40, 42, 45, 46, 47, 48,

49, 50, 68): Signal Ground. All small-signal components

and compensation components should connect to this

ground, which in turn connects to PGND at one point.

BOOST (Pin 29): Boosted Floating Driver Supply. The

(+) terminal of the bootstrap capacitor CB connects here.

This pin swings from a diode voltage drop below INTVCC

up to VIN + INTVCC.

RUN/SS (Pin 30): Run Control and Soft-Start Input. A

capacitor to ground at this pin sets the ramp time to full

output current (approximately 3s/μF) and the time delay

for overcurrent latchoff (see Applications Information).

Forcing this pin below 0.8V shuts down the device.

VON (Pin 35): On-Time Voltage Input. Voltage trip point

for the on-time comparator. Tying this pin to the output

volt-age or an external resistive divider from the output

makes the on-time proportional to VOUT. The compara-

tor input defaults to 0.7V when the pin is grounded and

defaults to 2.4V when the pin is tied to INTVCC. Tie this

pin to INTVCC in high VOUT applications to use a lower

RON value.

PGOOD (Pin 36): Power Good Output. Open drain logic

output that is pulled to ground when the output voltage

is not within ±10% of the regulation point.

VRNG (Pin 37): Current Limit Range Input. The voltage

at this pin adjusts maximum valley current and can be

set from 0.7V to 1V by a resistive divider from INTVCC.

It defaults to 0.7V if the VRNG pin is tied to ground which

results in a typical 10A current limit.

ITH (Pin 38): Current Control Threshold and Error Amplifier

Compensation Point. The current comparator threshold

increases with this control voltage. The voltage ranges

from 0V to 2.4V with 0.8V corresponding to zero sense

voltage (zero current).

FCB (Pin 39): Forced Continuous Input. Tie this pin to

ground to force continuous synchronous operation at low

load, to INTVCC to enable discontinuous mode operation at

low load or to a resistive divider from a secondary output

when using a secondary winding.

ION (Pin 41): On-Time Current Input. Tie a resistor from VIN

to this pin to set the one-shot timer current and thereby

set the switching frequency.

VFB (Pin 43): Error Amplifier Feedback Input. This pin

connects the error amplifier input to an external resistive

divider from VOUT.

EXTVCC (Pin 44): External VCC Input. When EXTVCC ex-

ceeds 4.7V, an internal switch connects this pin to INTVCC

and shuts down the internal regulator so that controller and

gate drive power is drawn from EXTVCC. Do not exceed

7V at this pin and ensure that EXTVCC < VIN.

SVIN (Pins 51, 52): Supply pin for internal PWM controller.

INTVCC (Pins 53, 54): Internal 5V Regulator Output. The

driver and control circuits are powered from this voltage.

Decouple this pin to power ground with a minimum of

4.7μF low ESR tantalum or ceramic capacitor.

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