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UCC28700 Datasheet, PDF (20/30 Pages) Texas Instruments – Constant-Voltage, Constant-Current Controller With Primary-Side Regulation
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UCC28700, UCC28701
UCC28702, UCC28703
SLUSB41 – JULY 2012
www.ti.com
Voltage Terms in Volts
• VBLK: highest bulk capacitor voltage for stand-by power measurement.
• VBULK(min): minimum voltage on CB1 and CB2 at full power.
• VOCBC: target cable compensation voltage at the output terminals.
• VCBC(max): maximum voltage at the CBC pin at the maximum converter output current (see ELECTRICAL
CHARACTERISTICS).
• VCCR: constant-current regulating voltage (see ELECTRICAL CHARACTERISTICS).
• VCST(max): CS pin maximum current-sense threshold (see ELECTRICAL CHARACTERISTICS).
• VCST(min): CS pin minimum current-sense threshold (see ELECTRICAL CHARACTERISTICS).
• VDD(off): UVLO turn-off voltage (see ELECTRICAL CHARACTERISTICS).
• VDD(on): UVLO turn-on voltage (see ELECTRICAL CHARACTERISTICS).
• VOΔ: output voltage drop allowed during the load-step transient.
• VDSPK: peak MOSFET drain-to-source voltage at high line.
• VF: secondary rectifier forward voltage drop at near-zero current.
• VFA: auxiliary rectifier forward voltage drop.
• VLK: estimated leakage inductance energy reset voltage.
• VOCV: regulated output voltage of the converter.
• VOCC: target lowest converter output voltage in constant-current regulation.
• VREV: peak reverse voltage on the secondary rectifier.
• VRIPPLE: output peak-to-peak ripple voltage at full-load.
• VVSR: CV regulating level at the VS input (see ELECTRICAL CHARACTERISTICS).
AC Voltage Terms in VRMS
• VIN(max): maximum input voltage to the converter.
• VIN(min): minimum input voltage to the converter.
• VIN(run): converter input start-up (run) voltage.
Efficiency Terms
• ηSB: estimated efficiency of the converter at no-load condition, not including start-up resistance or bias losses.
For a 5-V USB charger application, 60% to 65% is a good initial estimate.
• η: converter overall efficiency.
• ηXFMR: transformer primary-to-secondary power transfer efficiency.
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