ADPL74101 datasheet(11/49 Pages) AD

11 / 49 page

Data Sheet

ADPL74101

analog.com

Rev. 0

11 of 49

PIN CONFIGURATIONS AND FUNCTION DESCRIPTIONS

Figure 3. Pin Configuration

Table 3. Pin Descriptions

NAME

DESCRIPTION

PLLIN/

SPREAD

External Synchronization Input to Phase Detector/Spread Spectrum Enable. When an

external clock is applied to PLLIN/SPREAD, the phase-locked loop forces the rising TG

signal to synchronize with the rising edge of the external clock. When not

synchronizing to an external clock, tie this input to INTVCC to enable spread spectrum

dithering of the oscillator, or to GND to disable spread spectrum dithering.

MODE

Mode Select Input. This input determines how the ADPL74101 operates at light loads.

Connect the MODE to GND to select the Burst Mode operation. An internal 100kΩ

resistor to GND also invokes Burst Mode operation when MODE is floating. Connect

MODE to INTVCC to force continuous inductor current operation. Tying MODE to INTVCC

through a 100kΩ resistor selects the pulse skipping operation.

FREQ

Frequency Control Pin for the Internal Voltage-Controlled Oscillator (VCO). Connect

FREQ to GND for a fixed frequency of 370kHz. Program frequencies between 100kHz

and 1MHz by using a resistor between FREQ and GND. Minimize the capacitance on

FREQ.

TRACK/SS

External Tracking/Soft Start Input. TRACK/SS regulates the VFB voltage to the lesser of

0.8V or the voltage on the TRACK/SS pin. An internal 12µA pull-up current source is

connected to TRACK/SS. A capacitor to GND at TRACK/SS sets the ramp time to the

final regulated output voltage. The ramp time is equal to 1ms for every 12.5nF of

capacitance. Alternatively, a resistor divider on another voltage supply connected to

TRACK/SS allows the output to track the other supply during startup.

GND

Ground. This pin must be soldered to the printed circuit board (PCB) GND.

TOP VIEW

(Not to Scale)

ADPL74101

PLLIN/SPREAD

MODE

FREQ

TRACK/SS

GND

VPRG

VIN

DRVCC

SENSE+

VFB

ITH

ILIM

PGOOD

GND

NOTES

1. THE EXPOSED PAD (PIN 29) MUST BE SOLDERED TO PCB GROUND

FOR RATED ELECTRICAL AND THERMAL PERFORMANCE.

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