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## TPS254900A-Q1 Datasheet(PDF) 19 Page - Texas Instruments

 Part No. TPS254900A-Q1 Description Automotive USB Host Charger With Short-to-VBATT Protection Download 39 Pages Scroll/Zoom 100% Maker TI1 [Texas Instruments] Homepage http://www.ti.com Logo

## TPS254900A-Q1 Datasheet(HTML) 19 Page - Texas Instruments

 19 / 39 page (OUT)(FB)(G)(FA )(FB)(G)VRRRV/ R=--FADS(on)(WIRE)(CS)R(rR) / G=+INOUTCSR1R3To Regulator OUTTo LoadTo RegulatorResistor DividerV(OUT)R(FA)R(G)R(FB)FBC(BUS)R(WIRE)R(LOAD)C(COMP)rDS(on)R219TPS254900A-Q1www.ti.comSLUSCU5A – NOVEMBER 2017 – REVISED JANUARY 2018Product Folder Links: TPS254900A-Q1Submit Documentation FeedbackCopyright © 2017–2018, Texas Instruments IncorporatedFigure 38. Cable Compensation Equivalent Circuit8.3.2.1 Design ProcedureTo start the procedure, the total resistance, including the power switch rDS(on) and wire resistance R(WIRE), mustbe known.1. Choose R(G) following the voltage-regulator feedback resistor-divider design guideline.2. Calculate R(FA) according to Equation 1.(1)3. Calculate R(FB) according to Equation 2.(2)4. C(COMP) in parallel with R(FA) is required to stablilize V(OUT) when C(BUS) is large. Start with C(COMP) ≥ 3 × G(CS)× C(OUT), then adjust C(COMP) to optimize the load transient of the voltage regulator output. V(OUT) stabilityshould always be verified in the end application circuit.8.3.3 D+ and D– ProtectionD+ and D– protection consists of ESD and OVP (overvoltage protection). The DP_IN and DM_IN pins provideESD protection up to ±15 kV (air discharge) and ±8 kV (contact discharge) per IEC 61000-4-2 (see the ESDRatings section for test conditions).The ESD stress seen at DP_IN and DM_IN is impacted by many external factors, like the parasitic resistanceand inductance between ESD test points and the DP_IN and DM_IN pins. For air discharge, the temperature andhumidity of the environment can cause some difference, so the IEC performance should always be verified in theend-application circuit.The IEC ESD performance of the TPS254900A-Q1 device depends on the capacitance connected from BIAS toGND. A 2.2-µF capacitor placed close to the BIAS pin is recommended. Connect the BIAS pin to OUT using a5.1-kΩ resistor as a discharge path for the ESD stress.OVP protection is provided for short-to-VBUS or short-to-battery conditions in the vehicle harness, preventingdamage to the upstream USB transceiver or hub. When the voltage on DP_IN or DM_IN exceeds 3.9 V (typical),the TPS254900A-Q1 device quickly responds to block the high-voltage reverse connection to DP_OUT andDM_OUT. Overcurrent short-to-GND protection for D+ and D– is provided by the upstream USB transceiver.8.3.4 VBUS OVP ProtectionThe TPS254900A-Q1 OUT pin can withstand up to 18 V. The internal MOSFET turns off quickly when a short-to-battery condition occurs.