Datasheet LTC7151S (Analog Devices) - 7

LTC7151S
PIN FUNCTIONS CLKOUT (Pin 1):
Output Clock Signal for PolyPhase
FB (Pin 23):
Feedback Input to the Error Amplifier of the Operation. The phase of CLKOUT with respect to CLKIN Step-Down Regulator. Connect resistor divider tap to this is determined by the state of the PHMODE pin. CLKOUT’s pin. The output voltage can be adjusted from 0.5V to 5.5V. peak-to-peak amplitude is INTVCC to GND.
ITH (Pin 24):
Error Amplifier Output and Switching
RUN (Pin 2):
Logic Controlled RUN Input. Do not leave Regulator Compensation Point. The current comparator’s this pin floating. Logic High activates the step-down trip threshold is linearly proportional to this voltage, regulator. whose normal range is from 0.3V to 1.8V.
SVIN (Pin 3):
Signal VIN. Filtered input voltage to the
TRACK/SS (Pin 25):
Output Tracking and Soft-Start Pin. on-chip 3.3V regulator. Bypass signal into the SVIN pin Allows the user to control the rise time of the output with a 0.1µF ceramic capacitor. voltage. Putting a voltage between 0.0V and 0.5V on this –
PV
pin relative to VOUT bypasses the internal reference input
IN (Pins 4, 5, 18, 19):
Power VIN. Input voltage to the on chip power MOSFETs. to the error amplifier and instead servos the FB pin relative to V – OUT to that voltage. There’s an internal 6µA pull-up
GND (Pins 6–8, 15–17, 29–32):
Ground for Power and current from INTVCC to this pin, so putting a capacitor Signal Ground. from this pin to V – OUT provides a soft-start function.
SW (Pins 9–14):
Switch Node Connection of External
PGOOD (Pin 26):
Output Power Good with Open-Drain Inductor. Voltage swing of SW is from a diode voltage Logic. PGOOD is pulled to ground when the voltage of the drop below ground to a diode voltage above PVIN. FB pin is not within ±7.5% of the internal 0.5V reference.
INTVCC (Pin 20):
Internal 3.3V Regulator Output. The
RT (Pin 27):
Switching Frequency Programming Pin. internal power drivers and control circuits are powered Connect an external resistor (between 405k to 54k) from from this voltage. Decouple this pin to power ground with this pin to GND to program the frequency from 400kHz a minimum of 4.7µF low ESR ceramic capacitor. to 3MHz.
MODE/SYNC (Pin 21):
Discontinuous Mode Select
PHMODE (Pin 28):
Control Input to Phase Selector. and Oscillator Synchronization Pin. Tie MODE/SYNC Determines the phase relationship between internal to GND for discontinuous mode of operation. Floating oscillator and CLKOUT. Tie it to INTVCC for 2-phase MODE/SYNC or tying it to a voltage above 1V will select operation, tie it to SGND for 3-phase operation, and tie it forced continuous mode. Furthermore, connecting MODE/ to INTVCC/2 (or float the pin) for 4-phase operation. SYNC to an external clock will synchronize the system clock to the external clock and puts the part in forced
Corner Pins:
Ground. These pins are for mechanical continuous mode. support only and can be left floating or tied to ground.
V – OUT (Pin 22):
Negative Return of Output Rail. Connect this pin directly to the bottom of the remote output capacitor near the load in order to minimize error incurred by voltage drop across the metal trace of the board. Rev. 0 For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Typical Applications Package Photo Typical Application Related Parts