LTC7821 PIN CONFIGURATIONELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the specified operatingjunction temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = VIN_SENSE = 48V, VRUN = 5V, EXTVCC = 9V,EXT_REF = 5.6V unless otherwise noted. SYMBOLPARAMETERCONDITIONSMINTYPMAXUNITSMain Control Loops VIN Input Voltage Range 10 72 V Output Voltage Range (Note 4) 0.9 VIN V – 2.5 2 VFB Regulated Feedback Voltage ITH Voltage (Note 5) l 0.792 0.8 0.808 V IFB Feedback Current (Note 5) ±10 ±50 nA VREFLNREG Reference Voltage Line Regulation VIN = 36V to 72V (Note 5) 0.003 0.02 %/V VLOADREG Output Voltage Load Regulation (Note 5) ΔITH Voltage = 1.2V to 0.7V l 0.016 0.1 % ΔITH Voltage = 1.2V to 1.6V l –0.016 –0.1 % gm Transconductance Amplifier gm ITH = 1.2V; Sink/Source 5µA (Note 5) 2 mmho IVIN Input DC Supply Current (Note 6) Normal Mode 0.5 mA Shutdown VRUN = 0V, EXTVCC = 0V 240 µA Precharging Phase VIN = 20V, VMID = VMID_SENSE = 9V, 40 mA VSW1 = 15V, VSW3 = 10V VIN = 48V, VMID = VMID_SENSE = 20V, 84 mA VSW1 ≥ 36V, VSW3 = 12V IVIN_SENSE Input DC Supply Current (Note 6) Normal Mode 1 mA Shutdown VRUN = 0V 45 µA IEXTVCC Input DC Supply Current (Note 6) 2.2 mA IMID MID Pin Current 45 μA IMID_SENSE MID_SENSE Pin Current 4 μA VUVLO VIN Undervoltage Lockout VIN Ramping Up l 8.8 9.4 V VUVLO_HYST UVLO Hysteresis 0.28 V V – SENSE Current Sense Threshold VISNS = 0V l 45 50 55 mV I + – SNS+/- ISNS+ and ISNS– Pin Current VISNS = VISNS = 12V l 1.2 μA ITRACK/SS Soft-Start Charge Current VTRACK/SS = 0V –9 –10 –11 μA VRUN_ON RUN Pin On Threshold VRUN Rising l 1.1 1.3 1.6 V IRUN RUN Pin Current VRUN = 0V 1 μA VRUN_HYST RUN Pin Hysteresis 0.1 V VEXT_REF_UC EXT_REF Upper Clamp Limit (Note 5) l 0.85 0.9 V VEXT_REF_LC EXT_REF Lower Clamp Limit (Note 5) l 0.40 0.45 V VSEL_EXT_REF EXT_REF De-Select Threshold (Ramping Up) 1.3 V IEXT_REF EXT_REF Pin Current VEXT_REF = 0.6V –150 nA VTEMP_TRIP TEMP Pin Trip Point, Rising l 1.22 1.25 V VTEMP_TRIP_HYST TEMP Pin Trip Point Hysteresis 100 mV ITEMP TEMP Pin Current VTEMP = 1V 1 nA VBSTUVLO Undervoltage Lockout of (BOOST1-SW1), Difference Voltage, Rising 4.4 V (BOOST2- VMID) and (BOOST3-SW3) VBSTUVLO_HYST Bootstrap Undervoltage Lockout Hysteresis 1.4 V TOUT TEMP Trip TimeOut 100 ms Rev A For more information www.analog.com 3 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Related Parts
