Datasheet LTC3727A-1 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | High Efficiency, 2-Phase Synchronous Step-Down Switching Regulators |
| Pages / Page | 32 / 3 — ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply … |
| File Format / Size | PDF / 341 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply over the full operating
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LTC3727A-1
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 15V, VRUN/SS1, 2 = 5V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
gm1, 2 Transconductance Amplifi er gm ITH1, 2 = 1.2V; Sink/Source 5μA (Note 4) 1.3 mmho gmGBW1, 2 Transconductance Amplifi er GBW ITH1, 2 = 1.2V (Note 4) 3 MHz IQ Input DC Supply Current (Note 5) Normal Mode VIN = 15V, EXTVCC Tied to VOUT1, VOUT1 = 8.5V 670 μA Shutdown VRUN/SS1, 2 = 0V 20 35 μA VFCB Forced Continuous Threshold l 0.76 0.800 0.84 V IFCB Forced Continuous Pin Current VFCB = 0.85V –0.30 –0.18 –0.05 μA VBINHIBIT Burst Inhibit (Constant Frequency) Measured at FCB pin 6.8 7.3 V Threshold UVLO Undervoltage Lockout VIN Ramping Down l 3.5 4 V VOVL Feedback Overvoltage Lockout Measured at VOSENSE1, 2 l 0.84 0.86 0.88 V I – – + + SENSE Sense Pins Total Source Current (Each Channel) VSENSE1 , 2 = VSENSE1 , 2 = 0V –85 –60 μA DFMAX Maximum Duty Factor In Dropout 98 99.4 % IRUN/SS1, 2 Soft-Start Charge Current VRUN/SS1, 2 = 1.9V 0.5 1.2 μA VRUN/SS1, 2 ON RUN/SS Pin ON Threshold VRUN/SS1, VRUN/SS2 Rising 1.0 1.5 1.9 V V – – SENSE(MAX) Maximum Current Sense Threshold VOSENSE1, 2 = 0.7V, VSENSE1 , 2 = 12V l 105 135 165 mV TG Transition Time: (Note 6) TG1, 2 tr Rise Time CLOAD = 3300pF 50 90 ns TG1, 2 tf Fall Time CLOAD = 3300pF 50 90 ns BG Transition Time: (Note 6) BG1, 2 tr Rise Time CLOAD = 3300pF 40 90 ns BG1, 2 tf Fall Time CLOAD = 3300pF 40 80 ns TG/BG t1D Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver 90 ns Synchronous Switch-On Delay Time BG/TG t2D Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver 90 ns Top Switch-On Delay Time tON(MIN) Minimum On-Time Tested with a Square Wave (Note 7) 120 ns
INTVCC Linear Regulator
VINTVCC Internal VCC Voltage 8.5V < VIN < 30V, VEXTVCC = 6V 7.2 7.5 7.8 V VLDO INT INTVCC Load Regulation ICC = 0mA to 20mA, VEXTVCC = 6V 0.2 1.0 % VLDO EXT EXTVCC Voltage Drop ICC = 20mA, VEXTVCC = 8.5V 70 160 mV VEXTVCC EXTVCC Switchover Voltage ICC = 20mA, EXTVCC Ramping Positive l 6.9 7.3 V VLDOHYS EXTVCC Hysteresis 0.3 V
Oscillator and Phase-Locked Loop
fNOM Nominal Frequency VPLLFLTR = 1.2V 350 380 430 kHz fLOW Lowest Frequency VPLLFLTR = 0V 220 255 290 kHz fHIGH Highest Frequency VPLLFLTR ≥ 2.4V 460 530 580 kHz RPLLIN PLLIN Input Resistance 100 kΩ IPLLFLTR Phase Detector Output Current Sinking Capability fPLLIN < fOSC –15 μA Sourcing Capability fPLLIN > fOSC 15 μA 3727a1fa 3
ELECTRICAL CHARACTERISTICS The
l
denotes the specifi cations which apply over the full operating temperature range, otherwise specifi cations are at TA = 25°C. VIN = 15V, VRUN/SS1, 2 = 5V unless otherwise noted. SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
gm1, 2 Transconductance Amplifi er gm ITH1, 2 = 1.2V; Sink/Source 5μA (Note 4) 1.3 mmho gmGBW1, 2 Transconductance Amplifi er GBW ITH1, 2 = 1.2V (Note 4) 3 MHz IQ Input DC Supply Current (Note 5) Normal Mode VIN = 15V, EXTVCC Tied to VOUT1, VOUT1 = 8.5V 670 μA Shutdown VRUN/SS1, 2 = 0V 20 35 μA VFCB Forced Continuous Threshold l 0.76 0.800 0.84 V IFCB Forced Continuous Pin Current VFCB = 0.85V –0.30 –0.18 –0.05 μA VBINHIBIT Burst Inhibit (Constant Frequency) Measured at FCB pin 6.8 7.3 V Threshold UVLO Undervoltage Lockout VIN Ramping Down l 3.5 4 V VOVL Feedback Overvoltage Lockout Measured at VOSENSE1, 2 l 0.84 0.86 0.88 V I – – + + SENSE Sense Pins Total Source Current (Each Channel) VSENSE1 , 2 = VSENSE1 , 2 = 0V –85 –60 μA DFMAX Maximum Duty Factor In Dropout 98 99.4 % IRUN/SS1, 2 Soft-Start Charge Current VRUN/SS1, 2 = 1.9V 0.5 1.2 μA VRUN/SS1, 2 ON RUN/SS Pin ON Threshold VRUN/SS1, VRUN/SS2 Rising 1.0 1.5 1.9 V V – – SENSE(MAX) Maximum Current Sense Threshold VOSENSE1, 2 = 0.7V, VSENSE1 , 2 = 12V l 105 135 165 mV TG Transition Time: (Note 6) TG1, 2 tr Rise Time CLOAD = 3300pF 50 90 ns TG1, 2 tf Fall Time CLOAD = 3300pF 50 90 ns BG Transition Time: (Note 6) BG1, 2 tr Rise Time CLOAD = 3300pF 40 90 ns BG1, 2 tf Fall Time CLOAD = 3300pF 40 80 ns TG/BG t1D Top Gate Off to Bottom Gate On Delay CLOAD = 3300pF Each Driver 90 ns Synchronous Switch-On Delay Time BG/TG t2D Bottom Gate Off to Top Gate On Delay CLOAD = 3300pF Each Driver 90 ns Top Switch-On Delay Time tON(MIN) Minimum On-Time Tested with a Square Wave (Note 7) 120 ns
INTVCC Linear Regulator
VINTVCC Internal VCC Voltage 8.5V < VIN < 30V, VEXTVCC = 6V 7.2 7.5 7.8 V VLDO INT INTVCC Load Regulation ICC = 0mA to 20mA, VEXTVCC = 6V 0.2 1.0 % VLDO EXT EXTVCC Voltage Drop ICC = 20mA, VEXTVCC = 8.5V 70 160 mV VEXTVCC EXTVCC Switchover Voltage ICC = 20mA, EXTVCC Ramping Positive l 6.9 7.3 V VLDOHYS EXTVCC Hysteresis 0.3 V
Oscillator and Phase-Locked Loop
fNOM Nominal Frequency VPLLFLTR = 1.2V 350 380 430 kHz fLOW Lowest Frequency VPLLFLTR = 0V 220 255 290 kHz fHIGH Highest Frequency VPLLFLTR ≥ 2.4V 460 530 580 kHz RPLLIN PLLIN Input Resistance 100 kΩ IPLLFLTR Phase Detector Output Current Sinking Capability fPLLIN < fOSC –15 μA Sourcing Capability fPLLIN > fOSC 15 μA 3727a1fa 3
