Datasheet LT3957A (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | Boost, Flyback, SEPIC and Inverting Converter with 5A, 40V Switch |
| Pages / Page | 28 / 3 — ELECTRICAL CHARACTERISTICS. The. denotes the specifications which apply … |
| File Format / Size | PDF / 567 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifications which apply over the full operating temp-
Model Line for this Datasheet
Text Version of Document
LT3957A
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating temp- erature range, otherwise specifications are at TA ≈ TJ = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Operating Range 3 40 V VIN Shutdown IQ EN/UVLO = 0V 0.1 1 μA EN/UVLO = 1.15V 6 μA VIN Operating IQ VC = 0.3V, RT = 41.2k 1.7 2.3 mA VIN Operating IQ with Internal LDO Disabled VC = 0.3V, RT = 41.2k, INTVCC = 5.5V 350 400 μA SW Pin Current Limit l 5 5.9 6.8 A SW Pin On Voltage ISW = 3A 100 mV SENSE2 Input Bias Current Current Out of Pin –65 μA
Error Amplifier
FBX Regulation Voltage (VFBX(REG)) FBX > 0V (Note 3) l 1.569 1.6 1.631 V FBX < 0V (Note 3) l –0.816 –0.800 –0.784 V FBX Overvoltage Lockout FBX > 0V (Note 4) 6 8 10 % FBX < 0V (Note 4) 7 11 14 % FBX Pin Input Current FBX = 1.6V (Note 3) 70 100 nA FBX = –0.8V (Note 3) –10 10 nA Transconductance gm (ΔIVC/ΔFBX) (Note 3) 230 μS VC Output Impedance (Note 3) 5 MΩ VFBX Line Regulation (ΔVFBX/[ΔVIN • VFBX(REG)]) FBX > 0V, 3V < VIN < 40V (Notes 3, 6) 0.04 0.06 %/V FBX < 0V, 3V < VIN < 40V (Notes 3, 6) 0.03 0.06 %/V VC Current Mode Gain (ΔVVC /ΔVSENSE) 10 V/V VC Source Current VC = 1.5V, FBX = 0V, Current Out of Pin –15 μA VC Sink Current FBX = 1.7V 12 μA FBX = –0.85V 11 μA VC Low Side Clamp Voltage FBX = 1.65V 0.8 V
Oscillator
Switching Frequency RT = 140k to SGND, FBX = 1.6V, VC = 1.5V 80 100 120 kHz RT = 41.2k to SGND, FBX = 1.6V, VC = 1.5V 270 300 330 kHz RT = 10.5k to SGND, FBX = 1.6V, VC = 1.5V 850 1000 1200 kHz RT Voltage FBX = 1.6V 1.2 V SW Minimum Off-Time 220 275 ns SW Minimum On-Time 240 320 ns SYNC Input Low 0.4 SYNC Input High 1.5 SS Pull-Up Current SS = 0V, Current Out of Pin –10 μA
Low Dropout Regulator
INTVCC Regulation Voltage l 5 5.2 5.45 V INTVCC Undervoltage Lockout Threshold Falling INTVCC 2.6 2.7 2.85 V UVLO Hysteresis 0.15 V 3957afa 3
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating temp- erature range, otherwise specifications are at TA ≈ TJ = 25°C. VIN = 24V, EN/UVLO = 24V, SENSE2 = 0V, unless otherwise noted. PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Operating Range 3 40 V VIN Shutdown IQ EN/UVLO = 0V 0.1 1 μA EN/UVLO = 1.15V 6 μA VIN Operating IQ VC = 0.3V, RT = 41.2k 1.7 2.3 mA VIN Operating IQ with Internal LDO Disabled VC = 0.3V, RT = 41.2k, INTVCC = 5.5V 350 400 μA SW Pin Current Limit l 5 5.9 6.8 A SW Pin On Voltage ISW = 3A 100 mV SENSE2 Input Bias Current Current Out of Pin –65 μA
Error Amplifier
FBX Regulation Voltage (VFBX(REG)) FBX > 0V (Note 3) l 1.569 1.6 1.631 V FBX < 0V (Note 3) l –0.816 –0.800 –0.784 V FBX Overvoltage Lockout FBX > 0V (Note 4) 6 8 10 % FBX < 0V (Note 4) 7 11 14 % FBX Pin Input Current FBX = 1.6V (Note 3) 70 100 nA FBX = –0.8V (Note 3) –10 10 nA Transconductance gm (ΔIVC/ΔFBX) (Note 3) 230 μS VC Output Impedance (Note 3) 5 MΩ VFBX Line Regulation (ΔVFBX/[ΔVIN • VFBX(REG)]) FBX > 0V, 3V < VIN < 40V (Notes 3, 6) 0.04 0.06 %/V FBX < 0V, 3V < VIN < 40V (Notes 3, 6) 0.03 0.06 %/V VC Current Mode Gain (ΔVVC /ΔVSENSE) 10 V/V VC Source Current VC = 1.5V, FBX = 0V, Current Out of Pin –15 μA VC Sink Current FBX = 1.7V 12 μA FBX = –0.85V 11 μA VC Low Side Clamp Voltage FBX = 1.65V 0.8 V
Oscillator
Switching Frequency RT = 140k to SGND, FBX = 1.6V, VC = 1.5V 80 100 120 kHz RT = 41.2k to SGND, FBX = 1.6V, VC = 1.5V 270 300 330 kHz RT = 10.5k to SGND, FBX = 1.6V, VC = 1.5V 850 1000 1200 kHz RT Voltage FBX = 1.6V 1.2 V SW Minimum Off-Time 220 275 ns SW Minimum On-Time 240 320 ns SYNC Input Low 0.4 SYNC Input High 1.5 SS Pull-Up Current SS = 0V, Current Out of Pin –10 μA
Low Dropout Regulator
INTVCC Regulation Voltage l 5 5.2 5.45 V INTVCC Undervoltage Lockout Threshold Falling INTVCC 2.6 2.7 2.85 V UVLO Hysteresis 0.15 V 3957afa 3
