Datasheet LT3922-1 (Analog Devices) - 3

LT3922-1
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C, VIN = 12V, VEN/UVLO = 2V unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS Reference
VREF Voltage IVREF = 0µA l 1.97 2 2.03 V IVREF = 500µA 1.985 2 2.015 V VREF Pin Current Limit VREF = 0V, Current Out of Pin 3.2 mA
LED Current Regulation
CTRL-Off Threshold (Falling) l 200 210 220 mV CTRL-Off Rising Hysteresis 15 mV CTRL Pin Current VCTRL = 2V −100 100 nA Sense Voltage (VISP−VISN) VCTRL = 2V (100%), VISP = 24V l 98 100 102 mV (Analog Input) VCTRL = 0.75V (50%), VISP = 24V l 48.5 50 51.5 mV VCTRL = 0.3V (5%), VISP = 24V l 4 5 6 mV ISP Pin Current VISP = 24.1V, VISN = 24V, VCTRL = 2V 75 µA ISN Pin Current VISP = 24.1V, VISN = 24V , VCTRL = 2V 75 µA Current Error Amplifier Transconductance VISP = 24V 140 µA/V
Duty Cycle Control of LED Current
Sense Voltage (VISP−VISN) CTRL Duty = 75% (100%), VISP = 24V 99 100 101 mV (Duty Cycle Input) CTRL Duty = 37.5% (50%), VISP = 24V 49 50 51 mV CTRL Duty = 15% (5%), VISP = 24V 4 5 6 mV CTRL Pulse Input High (VIH) 1.6 V CTRL Pulse Input Low (VIL) 0.4 V CTRL Pulse Input Frequency Range 10 200 kHz
Voltage Regulation
FB Regulation Voltage VCTRL = 2V l 1.175 1.200 1.225 V FB Pin Current FB in Regulation −100 100 nA Voltage Error Amplifier Transconductance 1000 µA/V
INTVCC Regulator
INTVCC Voltage 2.7 3 3.3 V INTVCC Pin Current Limit VINTVCC = 0V, Current Out of Pin 20 mA
Power Stage
Peak Current Limit VIN = 3V 2.3 2.55 2.8 A Bottom Switch Minimum Off-Time l 15 25 35 ns Bottom Switch On-Resistance 140 mΩ Top Switch On-Resistance 155 mΩ
Oscillator
Programmed Switching Frequency (fSW) RT = 45.3k, VSYNC/SPRD = 0V l 1880 2000 2120 kHz RT = 499k, VSYNC/SPRD = 0V l 175 200 245 kHz Spread Spectrum Frequency Range RT = 45.3k, VSYNC/SPRD = 3V 1880 2650 kHz RT = 499k, VSYNC/SPRD = 3V 175 306 kHz RT Pin Current Limit VRT = 0V, Current Out of Pin 75 µA SYNC/SPRD Threshold (Rising) 1.4 1.5 V SYNC/SPRD Falling Hysteresis 0.2 V SYNC/SPRD Pin Current VSYNC/SPRD = 5V −100 100 nA Rev 0 For more information www.analog.com 3 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION TYPICAL APPLICATION RELATED PARTS