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LTC4257-1 Datasheet(PDF) 3 Page - Linear Technology |
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LTC4257-1 Datasheet(HTML) 3 Page - Linear Technology |
3 / 32 page LTC4267 3 4267fc The ● denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 3) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VMARGIN VCLAMP1mA – VTURNON Margin ● 0.05 0.6 V IVPORTN_ON VPORTN Supply Current when ON VPORTN = –48V, POUT, ⎯P⎯W⎯R⎯G⎯D, SIGDISA Floating ● 3 mA IPVCC_ON PVCC Supply Current (Note 7) Normal Operation VITH/RUN – PGND = 1.3V ● 240 350 µA Start-Up PVCC – PGND = VTURNON – 100mV ● 40 90 µA IVPORTN_CLASS VPORTN Supply Current VPORTN = –17.5V, POUT Tied to VPORTP, RCLASS, ● 0.35 0.5 0.65 mA During Classification SIGDISA Floating (Note 8) ∆ICLASS Current Accuracy 10mA < ICLASS < 40mA, –12.5V ≤ VPORTN ≤ –21V ● ±3.5 % During Classification (Notes 9, 10) RSIGNATURE Signature Resistance –1.5V ≤ VPORTN ≤ – 9.5V, POUT Tied to VPORTP, ● 23.25 26.00 kΩ IEEE 802.3af 2-Point Measurement (Notes 4, 5) RINVALID Invalid Signature Resistance –1.5V ≤ VPORTN ≤ – 9.5V, SIGDISA and POUT Tied to ● 9 11.8 kΩ VPORTP, IEEE 802.3af 2-Point Measurement (Notes 4, 5) VIH Signature Disable With Respect to VPORTN ● 3 57 V High Level Input Voltage High Level Invalidates Signature (Note 11) VIL Signature Disable With Respect to VPORTN ● 0.45 V Low Level Input Voltage Low Level Enables Signature RINPUT Signature Disable, Input Resistance With Respect to VPORTN ● 100 kΩ VPG_OUT Power Good Output Low Voltage I = 1mA VPORTN = –48V, ● 0.5 V ⎯P⎯W⎯R⎯G⎯D Referenced to VPORTN Power Good Trip Point VPORTN = –48V, Voltage between VPORTN and POUT (Note 10) VPG _FALL POUT Falling ● 1.3 1.5 1.7 V VPG_RISE POUT Rising ● 2.7 3.0 3.3 V IPG_LEAK Power Good Leakage Current VPORTN = 0V, ⎯P⎯W⎯R⎯G⎯D FET Off, V⎯P⎯W⎯R⎯G⎯D = 57V ● 1 µA RON On-Resistance I = 300mA, VPORTN = –48V, Measured from 1.0 1.6 Ω VPORTN to POUT (Note 10) ● 2 Ω VITHSHDN Shutdown Threshold (at ITH/RUN) PVCC – PGND = VTURNON + 100mV ● 0.15 0.28 0.45 V ITHSTART Start-Up Current Source at ITH/RUN VITH/RUN – PGND = 0V, PVCC – PGND = 8V 0.2 0.3 0.4 µA VFB Regulated Feedback Voltage Referenced to PGND, PVCC – PGND = 8V (Note 12) ● 0.780 0.800 0.812 V IFB VFB Input Current PVCC – PGND = 8V (Note 12) 10 50 nA gm Error Amplifier Transconductance ITH/RUN Pin Load = ±5µA (Note 12) 200 333 500 µA/V ∆VO(LINE) Output Voltage Line Regulation VTURNOFF < PVCC < VCLAMP (Note 12) 0.05 mV/V ∆VO(LOAD) Output Voltage Load Regulation ITH/RUN Sinking 5µA, PVCC – PGND = 8V (Note 12) 3 mV/µA ITH/RUN Sourcing 5µA, PVCC – PGND = 8V (Note 12) 3 mV/µA IPOUT_LEAK POUT Leakage VPORTN = 0V, Power MOSFET Off, ● 150 µA POUT = 57V (Note 13) ILIM_HI Input Current Limit, High Level VPORTN = –48V, POUT = –43V (Note 14, 15) 0°C ≤ TA ≤ 70°C ● 325 375 400 mA – 40°C ≤ TA ≤ 85°C ● 300 375 400 mA ILIM_LO Input Current Limit, Low Level VPORTN = –48V, POUT = –43V (Note 14, 15) ● 80 140 180 mA fOSC Oscillator Frequency VITH/RUN – PGND = 1.3V, PVCC – PGND = 8V 180 200 240 kHz DCON(MIN) Minimum Switch On Duty Cycle VITH/RUN – PGND = 1.3V, VFB – PGND = 0.8V, 6 8 % PVCC – PGND = 8V DCON(MAX) Maximum Switch On Duty Cycle VITH/RUN – PGND = 1.3V, VFB – PGND = 0.8V, 70 80 90 % PVCC – PGND = 8V ELECTRICAL CHARACTERISTICS |
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