Datasheet LT3922 (Analog Devices) - 4

LT3922
e lecTrical characTerisTics The
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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 Soft-Start
SS Pin Charging Current VSS = 1V 20 µA SS Pin Discharging Current VSS = 2V 2 µA SS Lower Threshold 0.2 V SS Higher Threshold 1.7 V
Fault Detection
Open-Circuit Threshold (FB Rising) VISP = VISN = 20V l 1.117 1.140 1.163 V Open-Circuit Falling Hysteresis 50 mV LED Short-Circuit Threshold (VISP − VISN) VISP = 20V 150 mV FAULT Pull-Down Current VFAULT = 0.2V, VFB = 1.25V 0.8 mA FAULT Leakage Current VFAULT = 3V, VFB = 0.7V −100 100 nA
Overvoltage Protection
FB Overvoltage Threshold (Rising) l 1.240 1.266 1.292 V FB Overvoltage Falling Hysteresis 22 mV
LED Current Monitor
ISMON Voltage VISP − VISN = 100mV (100%), VISP = 24V l 0.980 1.000 1.020 V VISP − VISN = 10mV (10%), VISP = 24V l 80 100 120 mV
PWM Driver
PWMTG Gate Drive (VOUT – VPWMTG) VOUT = 20V, VPWM = 1.5V 9 10 11 V PWM Threshold (Rising) 1.4 V PWM Falling Hysteresis 0.2 V PWM Pin Current VPWM = 2V −100 100 nA PWM to PWMTG Propagation Delay CPWMTG = 2.1nF (Connected from VOUT to PWMTG) Turn-On VOUT = 20V 110 ns Turn-Off 140 ns
Internal PWM Dimming
PWM Voltage for 100% PWM Dimming RP = 28.7k, VREF = 2V 2.00 V PWM Voltage for 0% PWM Dimming RP = 28.7k, VREF = 2V 0.99 V PWM Dimming Accuracy RP = 28.7k, VREF = 2V, VPWM = 1.1V 7.5 10.5 13.5 % RP = 28.7k, VREF = 2V, VPWM = 1.9V 89 92 95 % PWM Dimming Frequency RP = 28.7k, RT = 45.3k, VSYNC/SPRD = 0V 7.34 7.81 8.28 kHz RP = 332k, RT = 45.3k, VSYNC/SPRD = 0V 115 122 129 Hz RP Pin Current Limit VRP = 0V, Current Out of Pin 65 µA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings LT3922I is guaranteed to meet performance specifications over the may cause permanent damage to the device. Exposure to any Absolute −40°C to 125°C operating junction temperature range. The LT3922H is Maximum Rating condition for extended periods may affect device guaranteed over the −40°C to 150°C operating junction temperature range. reliability and lifetime. Operating lifetime is derated at junction temperatures greater than 125°C.
Note 2:
Do not apply a positive or negative voltage source to these pins,
Note 4:
This IC includes overtemperature protection that is intended to otherwise permanent damage may occur. protect the device during momentary overload conditions. The maximum
Note 3:
The LT3922E is guaranteed to meet performance specifications rated junction temperature will be exceeded when this protection is active. from 0°C to 125°C junction temperature. Specifications over the −40°C Continuous operation above the specified absolute maximum operating to 125°C operating junction temperature range are assured by design, junction temperature may impair device reliability or permanently damage characterization and correlation with statistical process controls. The the device. 3922fa 4 For more information www.linear.com/LT3922 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 Revision History Typical Application Related Parts