LT3724IFE#TRPBF

LT3724 High Voltage, Current Mode Switching Regulator Controller FEATURES n n n n n n n n n n n n n DESCRIPTION Wide Input Range: 4V to 60V Output Voltages up to 36V (Step-Down) Burst Mode® Operation: 9V VBURST_EN = 0V, VFB = 1.35V VSHDN = 0V 4 7.5 3.65 TYP MAX 60 3.8 670 20 20 10 3.95 15 UNITS V V V mV µA µA µA 3724fd 2 LT3724 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 20V, VCC = BOOST = BURST_EN = 10V, SHDN = 2V, SENSE – = SENSE+ = 10V, SGND = PGND = SW = 0V, unless otherwise noted. SYMBOL PARAMETER CONDITIONS VBOOST Operating Voltage Range Operating Voltage Range (Note 5) UVLO Threshold (Rising) UVLO Threshold Hysteresis VBOOST - VSW VBOOST - VSW VBOOST - VSW IBOOST BOOST Supply Current (Note 6) BOOST Burst Mode Current BOOST Shutdown Current VBURST_EN = 0V VSHDN = 0V VCC Operating Voltage Range (Note 5) Output Voltage UVLO Threshold (Rising) UVLO Threshold Hysteresis IVCC VCC Supply Current (Note 6) VCC Burst Mode Current VCC Shutdown Current Short-Circuit Current VBURST_EN = 0V VSHDN = 0V Error Amp Reference Voltage Measured at VFB Pin VFB IFB Feedback Input Current VSHDN Enable Threshold (Rising) Threshold Hysteresis VSENSE Common Mode Range Current Limit Sense Voltage ISENSE Input Current (ISENSE+ + ISENSE–) fSW Operating Frequency Over Full Line and Load Range Soft-Start Disable Voltage Soft-Start Disable Hysteresis ISS Soft-Start Capacitor Control Current gm Error Amp Transconductance AV Error Amp DC Voltage Gain VC Error Amp Output Range IVC VTG TYP l l 5 400 MAX 75 20 1.4 0.1 0.1 l l l –30 l 1.224 1.215 VSENSE+ – VSENSE– 1.3 l l 0 140 VSENSE(CM) = 0V VSENSE(CM) = 2.5V VSENSE(CM) > 4V V V V mV 1.7 80 20 –55 2.1 mA µA µA mA 1.231 1.238 1.245 1.35 120 150 190 175 165 VFB Rising l 275 200 200 V V nA 1.4 V mV 36 175 V mV 400 2 –150 l l V V V mV mA µA µA 25 l UNITS 20 8.3 8 6.25 500 l MP Grade VFB(SS) MIN µA µA µA 210 220 225 kHz kHz kHz 1.185 300 V mV 2 µA 340 400 µmhos 62 dB 1.2 V Error Amp Sink/Source Current ±30 µA Gate Drive Output On Voltage (Note 7) CLOAD = 3300pF Gate Drive Output Off Voltage CLOAD = 3300pF 9.8 0.1 V V tTG Gate Drive Rise/Fall Time 60 ns tTG(OFF) Minimum Switch Off Time 350 ns tTG(ON) Minimum Switch On Time ISW SW Pin Sink Current Zero Current to Current Limit 10% to 90% or 90% to 10%, CLOAD = 3300pF l VSW = 2V 300 300 500 ns mA 3724fd 3 LT3724 ELECTRICAL CHARACTERISTICS temperature range. The LT3724MP is 100% tested and guaranteed over the –55°C to 125°C operating junction temperature range. Note 4: VIN voltages below the start-up threshold (7.5V) are only supported when the VCC is externally driven above 6.5V. Note 5: Operating range is dictated by MOSFET absolute maximum VGS. Note 6: Supply current specification does not include switch drive currents. Actual supply currents will be higher. Note 7: DC measurement of gate drive output “ON” voltage is typically 8.6V. Internal dynamic bootstrap operation yields typical gate “ON” voltages of 9.8V during standard switching operation. Standard operation gate “ON” voltage is not tested but guaranteed by design. Note 8: The –1V absolute maximum on the SW pin is a transient condition. It is guaranteed by design and not subject to test. Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3724 includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 3: The LT3724E is guaranteed to meet performance specifications from 0°C to 125°C junction temperature. Specifications over the – 40°C to 125°C operating junction temperature range are assured by design, characterization and correlation with statistical process controls. The LT3724I is guaranteed over the full –40°C to 125°C operating junction TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Threshold (Rising) vs Temperature Shutdown Threshold (Falling) vs Temperature 1.37 1.36 1.35 1.34 1.33 1.32 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 8.2 1.25 8.1 1.23 1.22 0 25 50 75 TEMPERATURE (°C) 7.5 –50 –25 125 70 ICC = 20mA TA = 25°C TA = 25°C ICC CURRENT LIMIT (mA) 8 7 VCC (V) 6 5 4 7.6 0 5 10 15 20 25 30 35 3 4 5 6 7 8 9 10 11 12 VIN (V) ICC (LOAD) (mA) 3724 G04 3724 G05 100 125 3724 G03 VCC vs VIN 7.7 0 25 50 75 TEMPERATURE (°C) 3724 G02 8.0 VCC (V) 100 9 7.8 7.8 7.6 1.20 –50 –25 VCC vs ICC(LOAD) 7.9 7.9 7.7 1.21 8.2 8.1 ICC = 20mA 8.0 1.24 3724 G01 7.5 V­CC vs Temperature 1.26 VCC (V) SHUTDOWN THRESHOLD, FALLING (V) SHUTDOWN THRESHOLD, RISING (V) 1.38 ICC Current Limit vs Temperature 60 50 40 30 20 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 125 3724 G06 3724fd 4 LT3724 TYPICAL PERFORMANCE CHARACTERISTICS Error Amp Transconductance vs Temperature ICC vs VCC (SHDN = 0V) 25 6.4 20 6.3 15 6.2 6.1 TA = 25°C 10 5 6.0 –50 –25 0 25 50 75 TEMPERATURE (°C) 100 0 125 0 2 4 6 8 I(SENSE+ + SENSE–) vs VSENSE (CM) 100 0 –100 320 –50 –25 1.234 220 1.233 210 200 190 180 1.231 1.230 1.229 1.228 50 25 75 0 TEMPERATURE (°C) 100 125 1.227 –50 –25 152 150 148 146 144 142 100 125 3724 G13 100 3724 G12 3.86 4.52 3.84 4.50 3.82 4.48 4.46 3.80 4.44 3.78 4.42 4.40 –50 –25 125 VIN UVLO THRESHOLD, FALLING (V) VIN UVLO THRESHOLD, RISING (V) 154 50 25 75 0 TEMPERATURE (°C) V­IN UVLO Threshold (Falling) vs Temperature 4.54 160 125 1.232 VIN UVLO Threshold (Rising) vs Temperature 156 100 3724 G11 Maximum Current Sense Threshold vs Temperature 158 50 25 75 0 TEMPERATURE (°C) Error Amp Reference vs Temperature 3724 G10 CURRENT SENSE THRESHOLD (mV) 325 230 170 –50 –25 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 VSENSE (CM) (V) 50 25 75 0 TEMPERATURE (°C) 330 3724 G09 ERROR AMP REFERENCE (V) OPERATING FREQUENCY (kHz) I(SENSE+ + SENSE–) (µA) 200 140 –50 –25 335 Operating Frequency vs Temperature 300 0 340 3724 G08 TA = 25°C –200 345 10 12 14 16 18 20 VCC (V) 3724 G07 400 350 ERROR AMP TRANSCONDUCTANCE (µMhos) 6.5 ICC (µA) VCC UVLO THRESHOLD, RISING (V) VCC UVLO Threshold (Rising) vs Temperature 50 25 75 0 TEMPERATURE (°C) 100 125 3724 G14 3.76 –50 –25 50 25 75 0 TEMPERATURE (°C) 100 125 3724 G15 3724fd 5 LT3724 PIN FUNCTIONS VIN (Pin 1): The VIN pin is the main supply pin and should be decoupled to SGND with a low ESR capacitor located close to the pin. NC (Pin 2): No Connection. SHDN (Pin 3): The SHDN pin has a precision IC enable threshold of 1.35V (rising) with 120mV of hysteresis. It is used to implement an undervoltage lockout (UVLO) circuit. See Application Information section for implementing a UVLO function. When the SHDN pin is pulled below a transistor VBE (0.7V), a low current shutdown mode is entered, all internal circuitry is disabled and the VIN supply current is reduced to approximately 10µA. Typical pin input bias current is