Datasheet LTC3609 (Analog Devices) - 8

LTC3609 pin FuncTions
PVIN (Pins 1, 2, 3, 4, 5, 6, 7, 48, 49, 50, 51, 52, 53): ITH (Pin 18):
Current Control Threshold and Error Amplifier Main Input Supply. Decouple this pin to power PGND with Compensation Point. The current comparator threshold the input capacitance, CIN. increases with this control voltage. The voltage ranges
SW (Pins 8, 33, 41, 42, 43, 44, 45, 46, 47, 55):
Switch from 0V to 2.4V with 0.8V corresponding to zero sense Node Connection to the Inductor. The (–) terminal of the voltage (zero current). bootstrap capacitor, CB, also connects here. This pin swings
FCB (Pin 19):
Forced Continuous Input. Tie this pin to from a diode voltage drop below ground up to VIN. ground to force continuous synchronous operation at low
NC (Pins 9, 21, 24, 25, 28):
No Connection. load, to INTVCC to enable discontinuous mode operation at low load or to a resistive divider from a secondary output
SGND (Pins 10, 14, 15, 20, 26, 27, 54):
Signal Ground. All when using a secondary winding. small-signal components and compensation components should connect to this ground, which in turn connects to
ION (Pin 22):
On-Time Current Input. Tie a resistor from VIN PGND at one point. to this pin to set the one-shot timer current and thereby set the switching frequency.
BOOST (Pin 11):
Boosted Floating Driver Supply. The (+) terminal of the bootstrap capacitor, C
VFB (Pin 23):
Error Amplifier Feedback Input. This pin B, connects here. This pin swings from a diode voltage drop below INTV connects the error amplifier input to an external resistive CC up to V divider from VOUT. IN + INTVCC.
RUN/SS (Pin 12):
Run Control and Soft-Start Input. A
EXTVCC (Pin 29):
External VCC Input. When EXTVCC exceeds capacitor to ground at this pin sets the ramp time to full 4.7V, an internal switch connects this pin to INTVCC and output current (approximately 3s/µF) and the time delay shuts down the internal regulator so that controller and for overcurrent latchoff (see Applications Information). gate drive power is drawn from EXTVCC. Do not exceed Forcing this pin below 0.8V shuts down the device. 7V at this pin and ensure that EXTVCC < VIN.
V SVIN (Pin 30):
Supply Pin for Internal PWM Controller.
ON (Pin 13):
On-Time Voltage Input. Voltage trip point for the on-time comparator. Tying this pin to the output volt-
INTVCC (Pins 31, 32):
Internal 5V Regulator Output. The age or an external resistive divider from the output makes driver and control circuits are powered from this voltage. the on-time proportional to VOUT. The comparator input Decouple this pin to power ground with a minimum of defaults to 0.7V when the pin is grounded and defaults to 4.7µF low ESR tantalum or ceramic capacitor. 2.4V when the pin is tied to INTVCC. Tie this pin to INTVCC
PGND (Pins 34, 35, 36, 37, 38, 39, 40):
Power Ground. in high VOUT applications to use a lower RON value. Connect this pin closely to the (–) terminal of CVCC and
PGOOD (Pin 16):
Power Good Output. Open-drain logic the (–) terminal of CIN. output that is pulled to ground when the output voltage is not within ±10% of the regulation point.
VRNG (Pin 17):
Current Limit Range Input. The voltage at this pin adjusts maximum valley current and can be set from 0.7V to 1.2V by a resistive divider from INTVCC. It defaults to 0.7V if the VRNG pin is tied to ground which results in a typical 9A current limit. 3609fb Document Outline Features Description Applications 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