Datasheet LTC3608 (Analog Devices) - 8

LTC3608 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
SGND (Pins 10, 14, 15, 20, 26, 27, 54):
Signal Ground. All load, to INTVCC to enable discontinuous mode operation at small-signal components and compensation components low load or to a resistive divider from a secondary output should connect to this ground, which in turn connects to when using a secondary winding. PGND at one point.
NC (Pins 9, 21, 24, 25, 28):
No Connection.
BOOST (Pin 11):
Boosted Floating Driver Supply. The (+)
ION (Pin 22):
On-Time Current Input. Tie a resistor from VIN terminal of the bootstrap capacitor, CB, connects here. to this pin to set the one-shot timer current and thereby This pin swings from a diode voltage drop below INTVCC set the switching frequency. up to VIN + INTVCC.
VFB (Pin 23):
Error Amplifier Feedback Input. This pin
RUN/SS (Pin 12):
Run Control and Soft-Start Input. A connects the error amplifier input to an external resistive capacitor to ground at this pin sets the ramp time to full divider from VOUT. output current (approximately 3s/µF) and the time delay
EXTV
for overcurrent latchoff (see Applications Information).
CC (Pin 29):
External VCC Input. When EXTVCC exceeds 4.7V, an internal switch connects this pin to INTV Forcing this pin below 0.8V shuts down the device. CC and shuts down the internal regulator so that controller and
VON (Pin 13):
On-Time Voltage Input. Voltage trip point for gate drive power is drawn from EXTVCC. Do not exceed the on-time comparator. Tying this pin to the output volt- 7V at this pin and ensure that EXTVCC < VIN. age or an external resistive divider from the output makes
SV
the on-time proportional to V
IN (Pin 30):
Supply Pin for Internal PWM Controller. OUT. The comparator input defaults to 0.7V when the pin is grounded and defaults to
INTVCC (Pins 31, 32):
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 4.7µF low ESR tantalum or ceramic capacitor.
PGOOD (Pin 16):
Power Good Output. Open-drain logic output that is pulled to ground when the output voltage
PGND (Pins 34, 35, 36, 37, 38, 39, 40):
Power Ground. is not within ±10% of the regulation point. Connect this pin closely to the (–) terminal of CVCC and the (–) terminal of C
V
IN.
RNG (Pin 17):
Current Limit Range Input. The voltage at this pin adjusts maximum valley current and can be set from 0.5V to 0.7V by a resistive divider from INTVCC. It defaults to 0.7V if the VRNG pin is tied to ground which results in a typical 16A current limit. 3608fc 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