Datasheet LT3688 (Analog Devices) - 3
| Manufacturer | Analog Devices |
| Description | Dual 800mA Step-Down Switching Regulator with Power-On Reset and Watchdog Timer |
| Pages / Page | 28 / 3 — ELECTRICAL CHARACTERISTICS. denotes the specifi cations which apply over … |
| File Format / Size | PDF / 430 Kb |
| Document Language | English |
ELECTRICAL CHARACTERISTICS. denotes the specifi cations which apply over the full operating
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LT3688
Th ELECTRICAL CHARACTERISTICS e
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C. VIN = 12V, unless otherwise noted. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Undervoltage Lockout l 3 3.5 3.8 V Quiescent Current from VIN VEN/UVLO = 0.3V 0.01 1 μA VBIAS = 5V, Not Switching l 65 105 μA VBIAS = 0V, Not Switching 235 310 μA Quiescent Current from BIAS VEN/UVLO = 0.3V 0.01 1 μA VBIAS = 5V, Not Switching l 155 200 μA VBIAS = 0V, Not Switching –5 –20 μA FB Voltage 0.790 0.800 0.810 V l 0.784 0.814 V FB Pin Bias Current VFB = 0.800V l –3 –50 nA FB Voltage Line Regulation 5V < VIN < 36V 0.002 %/V Switching Frequency RT = 20k, VBST = 12V l 1.85 2.1 2.35 MHz RT = 110k, VBST = 12V l 460 500 540 kHz Minimum Off-Time (Note 4) VBST = 12V l 115 180 ns Switch Current Limit (Note 5) DC = 15% l 1.2 1.7 2.2 A Switch VCESAT ISW = 0.8A 280 mV Switch Leakage Current (Note 8) –0.01 –1 μA DA Current Limit l 0.9 1.2 1.6 A Boost Schottky Reverse Leakage VBIAS = 0V 0.01 2 μA Minimum BST Voltage above SW 2.15 2.5 V BST Pin Current ISW = 0.8A 15 25 mA EN/UVLO Threshold Voltage l 1.15 1.25 1.35 V EN/UVLO Input Current VEN/UVLO = 1.35V 0.3 μA VEN/UVLO = 1.15V 2.5 4 6 μA Threshold Current Hysteresis 2.5 3.7 5.5 μA RUN/SS Pin Current VRUN/SS = 0V –1.4 –2.8 –4 μA RUN/SS Switching Threshold 0.15 0.8 1 V SYNC Threshold Voltage 0.4 0.8 1.3 V VUV Reset Threshold % of FB Voltage, VFB Falling l 88 90 92 % tRST Reset Timeout Period CPOR = 4700pF l 21.2 23.5 25.8 ms tWDU Watchdog Window Upper Boundary CWDT = 1000pF l 18 20 22 ms tWDL Watchdog Window Lower Boundary CWDT = 1000pF l 0.8 1.25 1.6 ms tWDTO Watchdog Timeout Period CWDT = 1000pF 2.5 ms RST Output Voltage Low ISINK = 2.5mA, VFB = 0.6V l 0.2 0.4 V ISINK = 100μA, VFB = 0.6V l 0.01 0.3 V tUV UV Detect to RST Asserted VFB Set to 0.680V l 4 10 30 μs WDI Input Threshold l 0.4 0.95 1.3 V WDI Input Pull-Up Current –2 μA WDI Input Pulse Width l 300 ns WDE Threshold Voltage l 0.4 0.65 1 V WDE Input Pull-Down Current VWDE = 1.2V 3.5 μA WDO Output Voltage Low ISINK = 2.5mA l 0.2 0.4 V ISINK = 100μA l 0.01 0.3 V 3688f 3
Th ELECTRICAL CHARACTERISTICS e
l
denotes the specifi cations which apply over the full operating junction temperature range, otherwise specifi cations are at TA = 25°C. VIN = 12V, unless otherwise noted. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN Undervoltage Lockout l 3 3.5 3.8 V Quiescent Current from VIN VEN/UVLO = 0.3V 0.01 1 μA VBIAS = 5V, Not Switching l 65 105 μA VBIAS = 0V, Not Switching 235 310 μA Quiescent Current from BIAS VEN/UVLO = 0.3V 0.01 1 μA VBIAS = 5V, Not Switching l 155 200 μA VBIAS = 0V, Not Switching –5 –20 μA FB Voltage 0.790 0.800 0.810 V l 0.784 0.814 V FB Pin Bias Current VFB = 0.800V l –3 –50 nA FB Voltage Line Regulation 5V < VIN < 36V 0.002 %/V Switching Frequency RT = 20k, VBST = 12V l 1.85 2.1 2.35 MHz RT = 110k, VBST = 12V l 460 500 540 kHz Minimum Off-Time (Note 4) VBST = 12V l 115 180 ns Switch Current Limit (Note 5) DC = 15% l 1.2 1.7 2.2 A Switch VCESAT ISW = 0.8A 280 mV Switch Leakage Current (Note 8) –0.01 –1 μA DA Current Limit l 0.9 1.2 1.6 A Boost Schottky Reverse Leakage VBIAS = 0V 0.01 2 μA Minimum BST Voltage above SW 2.15 2.5 V BST Pin Current ISW = 0.8A 15 25 mA EN/UVLO Threshold Voltage l 1.15 1.25 1.35 V EN/UVLO Input Current VEN/UVLO = 1.35V 0.3 μA VEN/UVLO = 1.15V 2.5 4 6 μA Threshold Current Hysteresis 2.5 3.7 5.5 μA RUN/SS Pin Current VRUN/SS = 0V –1.4 –2.8 –4 μA RUN/SS Switching Threshold 0.15 0.8 1 V SYNC Threshold Voltage 0.4 0.8 1.3 V VUV Reset Threshold % of FB Voltage, VFB Falling l 88 90 92 % tRST Reset Timeout Period CPOR = 4700pF l 21.2 23.5 25.8 ms tWDU Watchdog Window Upper Boundary CWDT = 1000pF l 18 20 22 ms tWDL Watchdog Window Lower Boundary CWDT = 1000pF l 0.8 1.25 1.6 ms tWDTO Watchdog Timeout Period CWDT = 1000pF 2.5 ms RST Output Voltage Low ISINK = 2.5mA, VFB = 0.6V l 0.2 0.4 V ISINK = 100μA, VFB = 0.6V l 0.01 0.3 V tUV UV Detect to RST Asserted VFB Set to 0.680V l 4 10 30 μs WDI Input Threshold l 0.4 0.95 1.3 V WDI Input Pull-Up Current –2 μA WDI Input Pulse Width l 300 ns WDE Threshold Voltage l 0.4 0.65 1 V WDE Input Pull-Down Current VWDE = 1.2V 3.5 μA WDO Output Voltage Low ISINK = 2.5mA l 0.2 0.4 V ISINK = 100μA l 0.01 0.3 V 3688f 3
