Datasheet LTC3611 (Analog Devices) - 8

LTC3611 pin Functions
PGND (Pins 1, 2, 3, 56, 57, 58, 59, 60, 61, 62, 63, 64, VRNG (Pin 37):
Current Limit Range Input. The voltage
65):
Power Ground. Connect this pin closely to the (–) at this pin adjusts maximum val ey current and can be terminal of CVCC and the (–) terminal of CIN. set from 0.7V to 1V by a resistive divider from INTVCC.
SW (Pins 4, 5, 6, 7, 8, 9, 10, 11, 26, 55, 66):
Switch It defaults to 0.7V if the VRNG pin is tied to ground which Node Connection to the Inductor. The (–) terminal of the results in a typical 10A current limit. bootstrap capacitor, CB, also connects here. This pin swings
ITH (Pin 38):
Current Control Threshold and Error Amplifier from a diode voltage drop below ground up to VIN. Compensation Point. The current comparator threshold
PV
increases with this control voltage. The voltage ranges
IN (Pins 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 67):
Main Input Supply. Decouple this pin to from 0V to 2.4V with 0.8V corresponding to zero sense power PGND with the input capacitance, C voltage (zero current). IN.
NC (Pin 27):
No Connection.
FCB (Pin 39):
Forced Continuous Input. Tie this pin to ground to force continuous synchronous operation at low
SGND (Pins 28, 31, 32, 33, 34, 40, 42, 45, 46, 47, 48,
load, to INTVCC to enable discontinuous mode operation at
49, 50, 68):
Signal Ground. All smal -signal components low load or to a resistive divider from a secondary output and compensation components should connect to this when using a secondary winding. ground, which in turn connects to PGND at one point.
ION (Pin 41):
On-Time Current Input. Tie a resistor from VIN
BOOST (Pin 29):
Boosted Floating Driver Supply. The (+) to this pin to set the one-shot timer current and thereby terminal of the bootstrap capacitor, CB, connects here. set the switching frequency. This pin swings from a diode voltage drop below INTVCC up to V
VFB (Pin 43):
Error Amplifier Feedback Input. This pin IN + INTVCC. connects the error amplifier input to an external resistive
RUN/SS (Pin 30):
Run Control and Soft-Start Input. A divider from VOUT. capacitor to ground at this pin sets the ramp time to full output current (approximately 3s/μF) and the time delay
EXTVCC (Pin 44):
External VCC Input. When EXTVCC ex- for overcurrent latchoff (see Applications Information). ceeds 4.7V, an internal switch connects this pin to INTVCC Forcing this pin below 0.8V shuts down the device. and shuts down the internal regulator so that control er and gate drive power is drawn from EXTVCC. Do not exceed
VON (Pin 35):
On-Time Voltage Input. Voltage trip point for 7V at this pin and ensure that EXTVCC < VIN. the on-time comparator. Tying this pin to the output volt- age or an external resistive divider from the output makes
SVIN (Pins 51, 52):
Supply Pin for Internal PWM the on-time proportional to V Control er. OUT. The comparator input defaults to 0.7V when the pin is grounded and defaults to
INTVCC (Pins 53, 54):
Internal 5V Regulator Output. The 2.4V when the pin is tied to INTVCC. Tie this pin to INTVCC driver and control circuits are powered from this voltage. in high VOUT applications to use a lower RON value. Decouple this pin to power ground with a minimum of
PGOOD (Pin 36):
Power Good Output. Open-drain logic 4.7μF low ESR tantalum or ceramic capacitor. output that is pul ed to ground when the output voltage is not within ±10% of the regulation point. 3611fd 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