LTC3769 TYPICAL PERFORMANCE CHARACTERISTICS TA = 25°C unless otherwise noted.Maximum Current SenseCharge Pump Charging CurrentCharge Pump Charging CurrentThreshold vs Duty Cyclevs Operating Frequencyvs Switch Voltage 120 80 70 T = –60°C FREQ = GND ILIM = INTVCC 70 100 60 TAGE (mV) FREQ = INTV 60 T = –45°C CC 50 80 ILIM = FLOAT 50 T = 25°C 40 60 40 ILIM = GND T = 130°C 30 30 40 T = 155°C 20 20 20 10 10 MAXIMUM CURRENT SENSE VOL CHARGE PUMP CHARGING CURRENT (µA) CHARGE PUMP CHARGING CURRENT (µA) 0 0 0 0 10 20 30 40 50 60 70 80 90 100 50 150 250 350 450 550 650 750 5 15 25 35 45 55 65 DUTY CYCLE (%) OPERATING FREQUENCY (kHz) SWITCH VOLTAGE (V) 3769 G26 3769 G27 3769 G25 PIN FUNCTIONS (QFN/TSSOP)VBIAS (Pin 1/Pin 19): Main Supply Pin. It is normally FREQ (Pin 7/Pin 3): Frequency Control Pin for the Internal tied to the input supply VIN or to the output of the boost VCO. Connecting the pin to GND forces the VCO to a fixed converter. A bypass capacitor should be tied between this low frequency of 350kHz. Connecting the pin to INTVCC pin and the signal ground pin. The operating voltage range forces the VCO to a fixed high frequency of 535kHz. The on this pin is 4.5V to 60V (65V abs max). frequency can be programmed from 50kHz to 900kHz PGOOD (Pin 2/Pin 20): Power Good Indicator. Open-drain by connecting a resistor from the FREQ pin to GND. The logic output that is pulled to ground when the output volt- resistor and an internal 20μA source current create a volt- age is more than ±10% away from the regulated output age used by the internal oscillator to set the frequency. voltage. To avoid false trips the output voltage must be Alternatively, this pin can be driven with a DC voltage to outside the range for 45μs before this output is activated. vary the frequency of the internal oscillator. ILIM (Pin 3/Pin 1): Current Comparator Sense Voltage GND (Pin 8, 10, 24, Exposed Pad Pin 25/ Pin 4, Exposed Range Input. This pin is used to set the peak current Pad Pin 21): Ground. All ground pins must be connected sense voltage in the current comparator. Connect this and the exposed pad must be soldered to the PCB for pin to SGND, leave floating or connect to INTV rated electrical and thermal performance. CC to set the peak current sense voltage to 50mV, 75mV or 100mV, PLLIN/MODE (Pin 9/Pin 5): External Synchronization respectively. Input to Phase Detector and Forced Continuous Mode INTV Input. When an external clock is applied to this pin, the CC (Pins 5, 22/Pins 2, 17): Output of Internal 5.4V LDO. Power supply for control circuits and gate drivers. De- phase-locked loop will force the rising edge of BG to be couple pin 22/17 to GND with a minimum 4.7μF low ESR synchronized with the rising edge of the external clock. ceramic capacitor. Connect pin 5/2 to pin 22/17 with a When an external clock is applied to this pin, the OVMODE trace on the printed circuit board. pin is used to determine how the LTC3769 operates at light load. When not synchronizing to an external clock, this 3769fa 8 For more information www.linear.com/LTC3769 Document Outline Features Applications Description Typical Application Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Typical Applications Revision History Typical Application Related Parts