Datasheet LTC3858 (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 specifi cations which apply … |
| File Format / Size | PDF / 434 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply over the full operating
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LTC3858
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VLOADREG Output Voltage Load Regulation (Note4) Measured in Servo Loop, l 0.01 0.1 % ∆ITH Voltage = 1.2V to 0.7V (Note4) Measured in Servo Loop, l –0.01 –0.1 % ∆ITH Voltage = 1.2V to 2V gm1,2 Transconductance Amplifi er gm (Note 4) ITH1,2 = 1.2V, Sink/Source = 5μA 2 mmho IQ Input DC Supply Current (Note 5) Pulse Skip or Forced Continuous Mode RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 1.3 mA (One Channel On) RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Pulse Skip or Forced Continuous Mode RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 2 mA (Both Channels On) Sleep Mode (One Channel On) RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 170 250 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) 300 450 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– Pin Current Each Channel VOUT1,2 < INTVCC – 0.5V ±1 μA VOUT1,2 > INTVCC + 0.5V 550 950 μA DFMAX Maximum Duty Factor In Dropout, FREQ = 0V 98 99.4 % ISS1,2 Soft-Start Charge Current VSS1,2 = 0V 0.7 1.0 1.4 μA VRUN1,2 On RUN Pin On Threshold Voltage VRUN1, VRUN2 Rising l 1.23 1.28 1.33 V VRUN1,2 Hyst RUN Pin Hysteresis Voltage 50 mV VSS1,2 LA SS Pin Latch-Off Arming Threshold Voltage VSS1, VSS2 Rising from 1V 1.9 2 2.1 V VSS1,2 LT SS Pin Latch-Off Threshold Voltage VSS1, VSS2 Falling from 2V 1.3 1.5 1.7 V IDSC1,2 LT SS Discharge Current Short-Circuit Condition VFB1,2 = 0V, 7 10 13 μA VSS1,2 = 5V VSENSE(MAX) Maximum Current Sense Threshold Voltage VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = 0 l 22 30 36 mV VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = FLOAT l 43 50 57 mV VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = INTVCC l 64 75 86 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 Transistion Time: (Note 6) TG1,2 tr Rise Time CLOAD = 3300pF 25 ns TG1,2 tf Fall Time CLOAD = 3300pF 16 ns BG Transistion Time: (Note 6) BG1,2 tr Rise Time CLOAD = 3300pF 28 ns BG1,2 tf Fall Time CLOAD = 3300pF 13 ns TG/BG t1D Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver 30 ns Synchronous Switch-On Delay Time 3858fc 3
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C (Note 2). VIN = 12V, VRUN1,2 = 5V, EXTVCC = 0V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VLOADREG Output Voltage Load Regulation (Note4) Measured in Servo Loop, l 0.01 0.1 % ∆ITH Voltage = 1.2V to 0.7V (Note4) Measured in Servo Loop, l –0.01 –0.1 % ∆ITH Voltage = 1.2V to 2V gm1,2 Transconductance Amplifi er gm (Note 4) ITH1,2 = 1.2V, Sink/Source = 5μA 2 mmho IQ Input DC Supply Current (Note 5) Pulse Skip or Forced Continuous Mode RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 1.3 mA (One Channel On) RUN1 = 0V and RUN2 = 5V, VFB2 = 0.83V (No Load) Pulse Skip or Forced Continuous Mode RUN1,2 = 5V, VFB1,2 = 0.83V (No Load) 2 mA (Both Channels On) Sleep Mode (One Channel On) RUN1 = 5V and RUN2 = 0V, VFB1 = 0.83V (No Load) or 170 250 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) 300 450 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– Pin Current Each Channel VOUT1,2 < INTVCC – 0.5V ±1 μA VOUT1,2 > INTVCC + 0.5V 550 950 μA DFMAX Maximum Duty Factor In Dropout, FREQ = 0V 98 99.4 % ISS1,2 Soft-Start Charge Current VSS1,2 = 0V 0.7 1.0 1.4 μA VRUN1,2 On RUN Pin On Threshold Voltage VRUN1, VRUN2 Rising l 1.23 1.28 1.33 V VRUN1,2 Hyst RUN Pin Hysteresis Voltage 50 mV VSS1,2 LA SS Pin Latch-Off Arming Threshold Voltage VSS1, VSS2 Rising from 1V 1.9 2 2.1 V VSS1,2 LT SS Pin Latch-Off Threshold Voltage VSS1, VSS2 Falling from 2V 1.3 1.5 1.7 V IDSC1,2 LT SS Discharge Current Short-Circuit Condition VFB1,2 = 0V, 7 10 13 μA VSS1,2 = 5V VSENSE(MAX) Maximum Current Sense Threshold Voltage VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = 0 l 22 30 36 mV VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = FLOAT l 43 50 57 mV VFB1,2 = 0.7V, VSENSE1–,2– = 3.3V, ILIM = INTVCC l 64 75 86 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 Transistion Time: (Note 6) TG1,2 tr Rise Time CLOAD = 3300pF 25 ns TG1,2 tf Fall Time CLOAD = 3300pF 16 ns BG Transistion Time: (Note 6) BG1,2 tr Rise Time CLOAD = 3300pF 28 ns BG1,2 tf Fall Time CLOAD = 3300pF 13 ns TG/BG t1D Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver 30 ns Synchronous Switch-On Delay Time 3858fc 3
