SLUS600E April 2004 – December 2014 TPS51100
Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality.
The TPS51100 is typically used as a sink / source tracking termination regulator, witch converter a voltage from VTT.
|DESIGN PARAMETERS||EXAMPLE VALUE|
|VIN||4.75 V to 5.25 V|
|VDDQSNS, VLDOIN||1.8 V|
|Output Current||±3 A|
|REFERENCE DESIGNATOR||SPECIFICATION||MANUFACTURER||PART NUMBER|
|C1||10-μf, 6.3-V, X5R, 2012 (0805)||TDK||C2012JB0J106K|
|C2||0.1-μf, 50-V, X5R, 1608 (0603)||TDK||C1608JB1H104K|
For stable operation, total capacitance of the VTT output terminal can be equal to or greater than 20 μF. Attach two 10-μF ceramic capacitors in parallel to minimize the effect of ESR and ESL. If the ESR is greater than 2 mΩ, insert an R-C filter between the output and the VTTSNS input to achieve loop stability. The R-C filter time constant should be almost the same or slightly lower than the time constant of the output capacitor and its ESR.
Soft-start duration, tSS, is also a function of this output capacitance. Where ITTOCL = 2.2 A (typ), tSS can be calculated as,
Depending on the trace impedance between the VLDOIN bulk power supply to the part, transient increase of source current is supplied mostly by the charge from the VLDOIN input capacitor. Use a 10-μF (or more) ceramic capacitor to supply this transient charge. Provide more input capacitance as more output capacitance is used at VTT. In general, use 1/2 COUT for the input.
Add a ceramic capacitor with a value between 1 μF and 4.7 μF placed close to the VIN pin, to stabilize 5 V from any parasitic impedance from the supply.