Datasheet LTC3857-1 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | Low IQ, Dual, 2-Phase Synchronous Step-Down Controller |
| Pages / Page | 38 / 3 — ELECTRICAL CHARACTERISTICS. The. denotes the specifications which apply … |
| File Format / Size | PDF / 434 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifications which apply over the full operating junction
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LTC3857-1
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Operating Voltage Range 4 38 V VFB1,2 Regulated Feedback Voltage (Note 4) ITH1,2 Voltage = 1.2V –40°C to 125°C l 0.788 0.800 0.812 V –40°C to 85°C 0.792 0.800 0.808 V IFB1,2 Feedback Current (Note 4) ±5 ±50 nA VREFLNREG Reference Voltage Line Regulation (Note 4) VIN = 4.5V to 38V 0.002 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 4) Measured in Servo Loop, l 0.01 0.1 % ΔITH Voltage = 1.2V to 0.7V (Note 4) Measured in Servo Loop, l –0.01 –0.1 % ΔITH Voltage = 1.2V to 2V gm1,2 Transconductance Amplifier gm (Note 4) ITH1,2 = 1.2V, Sink/Source = 5μA 2 mmho IQ Input DC Supply Current (Note 5) Pulse-Skipping or Forced Continuous RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 2 mA Mode (One Channel On) RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Pulse-Skipping or Forced Continuous RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 2 mA Mode (Both Channels On) Sleep Mode (One Channel On) RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 50 75 μA RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Sleep Mode (Both Channels On) RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 65 120 μA Shutdown RUN1,2 = 0V 8 20 μA UVLO Undervoltage Lockout INTVCC Ramping Up l 4.0 4.2 V INTVCC Ramping Down l 3.6 3.8 4 V VOVL Feedback Overvoltage Protection Measured at VFB1,2, Relative to Regulated VFB1,2 7 10 13 % I + SENSE SENSE+ Pin Current Each Channel ±1 μA I – SENSE SENSE– Pins Current Each Channel V – SENSE < INTVCC – 0.5V ±1 μA V – SENSE > INTVCC + 0.5V 550 μA DFMAX Maximum Duty Factor In Dropout, FREQ = 0V 98 99.4 % ITRACK/SS1,2 Soft-Start Charge Current VTRACK1,2 = 0V 0.7 1.0 1.4 μA VRUN1,2 On RUN Pin On Threshold VRUN1, VRUN2 Rising l 1.21 1.26 1.31 V VRUN1,2 Hyst RUN Pin Hysteresis 50 mV VSENSE(MAX) Maximum Current Sense Threshold VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V l 43 50 57 mV
Gate Driver
TG1,2 Pull-Up On-Resistance 2.5 Ω Pull-Down On-Resistance 1.5 Ω BG1,2 Pull-Up On-Resistance 2.4 Ω Pull-Down On-Resistance 1.1 Ω TG Transition Time: (Note 6) TG1,2 tr Rise Time CLOAD = 3300pF 25 ns TG1,2 tf Fall Time CLOAD = 3300pF 16 ns BG Transition Time: (Note 6) BG1,2 tr Rise Time CLOAD = 3300pF 28 ns BG1,2 tf Fall Time CLOAD = 3300pF 13 ns 38571fc 3 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
ELECTRICAL CHARACTERISTICS The
l
denotes the specifications which apply over the full operating junction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Input Supply Operating Voltage Range 4 38 V VFB1,2 Regulated Feedback Voltage (Note 4) ITH1,2 Voltage = 1.2V –40°C to 125°C l 0.788 0.800 0.812 V –40°C to 85°C 0.792 0.800 0.808 V IFB1,2 Feedback Current (Note 4) ±5 ±50 nA VREFLNREG Reference Voltage Line Regulation (Note 4) VIN = 4.5V to 38V 0.002 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 4) Measured in Servo Loop, l 0.01 0.1 % ΔITH Voltage = 1.2V to 0.7V (Note 4) Measured in Servo Loop, l –0.01 –0.1 % ΔITH Voltage = 1.2V to 2V gm1,2 Transconductance Amplifier gm (Note 4) ITH1,2 = 1.2V, Sink/Source = 5μA 2 mmho IQ Input DC Supply Current (Note 5) Pulse-Skipping or Forced Continuous RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 2 mA Mode (One Channel On) RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Pulse-Skipping or Forced Continuous RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 2 mA Mode (Both Channels On) Sleep Mode (One Channel On) RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 50 75 μA RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Sleep Mode (Both Channels On) RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 65 120 μA Shutdown RUN1,2 = 0V 8 20 μA UVLO Undervoltage Lockout INTVCC Ramping Up l 4.0 4.2 V INTVCC Ramping Down l 3.6 3.8 4 V VOVL Feedback Overvoltage Protection Measured at VFB1,2, Relative to Regulated VFB1,2 7 10 13 % I + SENSE SENSE+ Pin Current Each Channel ±1 μA I – SENSE SENSE– Pins Current Each Channel V – SENSE < INTVCC – 0.5V ±1 μA V – SENSE > INTVCC + 0.5V 550 μA DFMAX Maximum Duty Factor In Dropout, FREQ = 0V 98 99.4 % ITRACK/SS1,2 Soft-Start Charge Current VTRACK1,2 = 0V 0.7 1.0 1.4 μA VRUN1,2 On RUN Pin On Threshold VRUN1, VRUN2 Rising l 1.21 1.26 1.31 V VRUN1,2 Hyst RUN Pin Hysteresis 50 mV VSENSE(MAX) Maximum Current Sense Threshold VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V l 43 50 57 mV
Gate Driver
TG1,2 Pull-Up On-Resistance 2.5 Ω Pull-Down On-Resistance 1.5 Ω BG1,2 Pull-Up On-Resistance 2.4 Ω Pull-Down On-Resistance 1.1 Ω TG Transition Time: (Note 6) TG1,2 tr Rise Time CLOAD = 3300pF 25 ns TG1,2 tf Fall Time CLOAD = 3300pF 16 ns BG Transition Time: (Note 6) BG1,2 tr Rise Time CLOAD = 3300pF 28 ns BG1,2 tf Fall Time CLOAD = 3300pF 13 ns 38571fc 3 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS FUNCTIONAL DIAGRAM OPERATION APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
