Datasheet LT1939 (Analog Devices) - 3

LT1939
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TJ = 25°C. VVIN = 15V, VRT/SYNC = 2V, unless otherwise specifi ed. PARAMETER CONDITIONS MIN TYP MAX UNITS
SS Sink Current VFB = 0V, VSS = 2V 300 600 900 μA SS POR Sink Current (Note 4) VFB = 0V, VSS = 2V, Cycle SHDN 400 600 800 μA SS POR Threshold VFB = 0V 50 100 150 mV SS to FB Offset (VSS – VFB) VVC = 1V, VSS = 0.4V 70 100 120 mV PG/PG Leakage VFB = 0.9V/0.7V, VPG/VPG = 25V 0.1 1 μA PG/ PG Threshold VPG = 0.4V 0.685 0.708 0.730 V PG/ PG Hysteresis VPG = 0.4V 20 30 40 mV PG Sink Current VPG = 0.4V, VFB = 0.7V 250 500 750 μA PG Sink Current VPG = 0.4V, VFB = 0.9V 500 800 1100 μA RT/SYNC Reference Voltage VFB1/2 = 0.9V, RRT/SYNC = 15k 0.75 0.850 0.975 V Switching Frequency RRT/SYNC = 90.9k 450 500 550 kHz RRT/SYNC = 90.9k l 425 500 625 kHz RRT/SYNC = 15k 2 2.4 2.8 MHz SYNC Frequency Range l 250 2500 kHz Minimum Switch On Time VFB = 0.7V, RRT/SYNC = 90.9k 140 ns Minimum Switch Off Time VFB = 0.7V, RRT/SYNC = 90.9k 120 ns Switch Leakage Current VSW = 0V 1 10 μA Switch Saturation Voltage ISW = 2A, VBST = 18V, VFB = 0.7V 450 mV Switch Peak Current VBST = 18V, VFB = 0.7V 2.3 2.8 3.5 A l 2.1 2.8 3.5 A Boost Current ISW = 2A, VBST = 18V, VFB = 0.7V 20 30 45 mA Minimum Boost Voltage (Note 5) ISW = 2A, VFB = 0.7V 2.2 3 V LFB Voltage VLDRV = 1.2V l 0.784 0.8 0.816 V LFB Line/Load Regulation VVIN = 3V to 25V, VLDRV = 8V l 0.776 0.8 0.824 V SS to LFB Offset (VSS – VLFB) VVC = 1V, VSS = 0.8V, VLDRV = VLFB 90 115 140 mV LFB Bias Current VLFB = 0.8V, VVC = 1V 115 300 nA LDRV Dropout VLDRV = 3V, ILDRV = 5mA l 0.8 1.2 1.6 V LDRV Maximum Current VLDRV = 0V l 9 13 18 mA
Note 1:
Stresses beyond those listed under Absolute Maximum Ratings
Note 4:
An internal power-on reset (POR) latch is set on the positive may cause permanent damage to the device. Exposure to any Absolute transition of the SHDN pin through its threshold. The output of the latch Maximum Rating condition for extended periods may affect device activates a current source on the SS pin which typically sinks 600μA, reliability and lifetime. discharging the SS capacitor. The latch is reset when the SS pin is driven
Note2:
The LT1939EDD is guaranteed to meet performance specifi cations below the soft-start POR threshold or the SHDN pin is taken below its from 0°C to 125°C junction temperature. Specifi cations over the –40°C threshold. to 125°C operating junction temperature range are assured by design,
Note 5:
This is the minimum voltage across the boost capacitor needed to characterization and correlation with statistical process controls. The guarantee full saturation of the internal power switch. LT1939IDD is guaranteed over the full –40°C to 125°C operating junction
Note 6:
This IC includes overtemperature protection that is intended temperature range. to protect the device during momentary overload conditions. Junction
Note 3:
Minimum input voltage is defi ned as the voltage where internal temperature will exceed the maximum operating junction temperature bias lines are regulated so that the reference voltage and oscillator remain when overtemperature protection is active. Continuous operation above constant. Actual minimum input voltage to maintain a regulated output the specifi ed maximum operating junction temperature may impair device will depend upon output voltage and load current. See Applications reliability. Information. 1939f 3