Datasheet LTC3728 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | Dual, 550kHz, 2-Phase Synchronous Step-Down Switching Regulator |
| Pages / Page | 36 / 3 — ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply … |
| File Format / Size | PDF / 1.7 Mb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. The. denotes the specifi cations which apply over the full operating
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LTC3728
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 Main Control Loops
VOSENSE1, 2 Regulated Feedback Voltage (Note 3); ITH1, 2 Voltage = 1.2V l 0.792 0.800 0.808 V IOSENSE1, 2 Feedback Current (Note 3) –5 –50 nA VREFLNREG Reference Voltage Line Regulation VIN = 3.6V to 30V (Note 3) 0.002 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 3) Measured in Servo Loop; ΔITH Voltage = 1.2V to 0.7V l 0.1 0.5 % Measured in Servo Loop; ΔITH Voltage = 1.2V to 2.0V l –0.1 –0.5 % gm1, 2 Transconductance Amplifi er gm ITH1, 2 = 1.2V; Sink/Source 5μA (Note 3) 1.3 mmho gmGBW1, 2 Transconductance Amplifi er GBW ITH1, 2 = 1.2V (Note 3) 3 MHzIQ Input DC Supply Current (Note 4) Normal Mode VIN = 15V; EXTVCC Tied to VOUT1; VOUT1 = 5V 450 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 –0.50 –0.18 –0.1 μA VBINHIBIT Burst Inhibit (Constant-Frequency) Measured at FCB Pin 4.3 4.8 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 ISENSE 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 VRUN/SS1, 2 LT RUN/SS Pin Latchoff Arming VRUN/SS1, VRUN/SS2 Rising from 3V 3.8 4.5 V Threshold ISCL1, 2 RUN/SS Discharge Current Soft-Short Condition VOSENSE1, 2 = 0.5V; 0.5 2 4 μA VRUN/SS1, 2 = 4.5V ISDLHO Shutdown Latch Disable Current VOSENSE1, 2 = 0.5V 1.6 5 μA VSENSE(MAX) Maximum Current Sense Threshold VOSENSE1, 2 = 0.7V, VOSENSE1–, 2– = 5V 65 75 85 mV VOSENSE1, 2 = 0.7V, VOSENSE1–, 2– = 5V l 62 75 88 mV TG Transition Time: (Note 5) TG1, 2 tr Rise Time CLOAD = 3300pF 50 90 ns TG1, 2 tf Fall Time CLOAD = 3300pF 50 90 ns BG Transition Time: (Note 5) 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 Synchronous Switch-On Delay Time CLOAD = 3300pF Each Driver 90 ns BG/TG t2D Bottom Gate Off to Top Gate On Delay Top Switch-On Delay Time CLOAD = 3300pF Each Driver 90 ns tON(MIN) Minimum On-Time Tested with a Square Wave (Note 6) 100 ns
INTVCC Linear Regulator
VINTVCC Internal VCC Voltage 6V < VIN < 30V, VEXTVCC = 4V 48 5.0 5.2 V VLDOINT INTVCC Load Regulation ICC = 0 to 20mA, VEXTVCC = 4V 0.2 1.0 % VLDOEXT EXTVCC Voltage Drop ICC = 20mA, VEXTVCC = 5V 80 160 mV 3728fg 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 Main Control Loops
VOSENSE1, 2 Regulated Feedback Voltage (Note 3); ITH1, 2 Voltage = 1.2V l 0.792 0.800 0.808 V IOSENSE1, 2 Feedback Current (Note 3) –5 –50 nA VREFLNREG Reference Voltage Line Regulation VIN = 3.6V to 30V (Note 3) 0.002 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 3) Measured in Servo Loop; ΔITH Voltage = 1.2V to 0.7V l 0.1 0.5 % Measured in Servo Loop; ΔITH Voltage = 1.2V to 2.0V l –0.1 –0.5 % gm1, 2 Transconductance Amplifi er gm ITH1, 2 = 1.2V; Sink/Source 5μA (Note 3) 1.3 mmho gmGBW1, 2 Transconductance Amplifi er GBW ITH1, 2 = 1.2V (Note 3) 3 MHzIQ Input DC Supply Current (Note 4) Normal Mode VIN = 15V; EXTVCC Tied to VOUT1; VOUT1 = 5V 450 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 –0.50 –0.18 –0.1 μA VBINHIBIT Burst Inhibit (Constant-Frequency) Measured at FCB Pin 4.3 4.8 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 ISENSE 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 VRUN/SS1, 2 LT RUN/SS Pin Latchoff Arming VRUN/SS1, VRUN/SS2 Rising from 3V 3.8 4.5 V Threshold ISCL1, 2 RUN/SS Discharge Current Soft-Short Condition VOSENSE1, 2 = 0.5V; 0.5 2 4 μA VRUN/SS1, 2 = 4.5V ISDLHO Shutdown Latch Disable Current VOSENSE1, 2 = 0.5V 1.6 5 μA VSENSE(MAX) Maximum Current Sense Threshold VOSENSE1, 2 = 0.7V, VOSENSE1–, 2– = 5V 65 75 85 mV VOSENSE1, 2 = 0.7V, VOSENSE1–, 2– = 5V l 62 75 88 mV TG Transition Time: (Note 5) TG1, 2 tr Rise Time CLOAD = 3300pF 50 90 ns TG1, 2 tf Fall Time CLOAD = 3300pF 50 90 ns BG Transition Time: (Note 5) 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 Synchronous Switch-On Delay Time CLOAD = 3300pF Each Driver 90 ns BG/TG t2D Bottom Gate Off to Top Gate On Delay Top Switch-On Delay Time CLOAD = 3300pF Each Driver 90 ns tON(MIN) Minimum On-Time Tested with a Square Wave (Note 6) 100 ns
INTVCC Linear Regulator
VINTVCC Internal VCC Voltage 6V < VIN < 30V, VEXTVCC = 4V 48 5.0 5.2 V VLDOINT INTVCC Load Regulation ICC = 0 to 20mA, VEXTVCC = 4V 0.2 1.0 % VLDOEXT EXTVCC Voltage Drop ICC = 20mA, VEXTVCC = 5V 80 160 mV 3728fg 3
