TurboTrans™ Technology

TurboTrans™ Selection

PTH04T240F

TurboTrans technology is a feature introduced in the T2 generation of the PTH/PTV family of power modules.

TurboTrans optimizes the transient response of the regulator with added external capacitance using a single

external resistor. Benefits of this technology include reduced output capacitance, minimized output voltage

deviation following a load transient, and enhanced stability when using ultra-low ESR output capacitors. The

amount of output capacitance required to meet a target output voltage deviation is reduced with TurboTrans

activated. Likewise, for a given amount of output capacitance, with TurboTrans engaged, the amplitude of the

voltage deviation following a load transient will be reduced. Applications requiring tight transient voltage

tolerances and minimized capacitor footprint area will benefit greatly from this technology.

(pin9). The value of the resistor directly corresponds to the amount of output capacitance required. All T2

products require a minimum value of output capacitance. For the PTH04T240F, the minimum required

capacitance is 1000

µF. When using TurboTrans, capacitors with a capacitance × ESR product below 10,000 µF

× m

Ω are required. (Multiply the capacitance (in

µF) by the ESR (in mΩ) to determine the capacitance × ESR

product.) See the Capacitor Selection section of the datasheet for a variety of capacitors that meet this criteria.

Figure 10 thru Figure 13 show the amount of output capacitance required to meet a desired transient voltage

deviation with and without TurboTrans for two capacitor types; TypeB (e.g. polymer-tantalum) and TypeC (e.g.

magnitude of the transient load step. Next, determine what type of output capacitors will be used. (If more than

one type of output capacitor is used, select the capacitor type that makes up the majority of your total output

capacitance.) Knowing this information, use the chart in Figure 10 through Figure 13 that corresponds to the

capacitor type selected. To use the chart, begin by dividing the maximum voltage deviation limit (in mV) by the

magnitude of your load step (in amperes). This gives a mV/A value. Find this value on the Y-axis of the

appropriate chart. Read across the graph to the 'With TurboTrans' plot. From this point, read down to the X-axis

resistor value can then be calculated using the equation or selected from the TurboTrans table. The TurboTrans

transient voltage deviation for 25%(2.5A), 50%(5A), and 75%(7.5A) output load steps.

The chart can also be used to determine the achievable transient voltage deviation for a given amount of output

capacitance. By selecting the amount of output capacitance along the X-axis, reading up to the desired 'With

TurboTrans'' curve, and then over to the Y-axis, gives the transient voltage deviation limit for that value of output

TurboTrans table.

As an example, consider a 5-V application requiring a 15 mV deviation during an 3A load transient. A majority of

330

µF, 10 mΩ ouput capacitors will be used. Use the 5-V, Type B capacitor chart, Figure 10. Dividing 15mV by

3A gives 5mV/A transient voltage deviation per ampere of transient load step. Select 5mV/A on the Y-axis and

read across to the 'With TurboTrans'' plot. Following this point down to the X-axis gives a minimum required

output capacitance of approximately 1900

µF. The required R

Copyright © 2008–2009, Texas Instruments Incorporated

Submit Documentation Feedback

15

Product Folder Link(s): PTH04T240F