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TurboTrans™ Technology

TurboTrans™ Selection

PTH08T210W

SLTS262D – OCTOBER 2005 – REVISED OCTOBER 2006

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. The, 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 benefit from this technology.

pin (pin 13). The value of the resistor directly corresponds to the amount of output capacitance required. All T2

products require a minimum value of output capacitance whether or not TurboTrans is used. For the

PTH08T210W, the minimum required capacitance is 470

µF. When using TurboTrans, capacitors with a

capacitance

× ESR product below 10,000 µF × mΩ are required. (Multiply the capacitance (in µF) by the ESR (in

m

Ω) to determine the capacitance × ESR product.) See the Capacitor Selection section of the datasheet for a

variety of capacitors that meet this criteria.

Figure 11 through Figure 16, show the amount of output capacitance required to meet a desired transient

voltage deviation with and without TurboTrans for several capacitor types; Type A (e.g. ceramic), Type B

required transient voltage deviation limits and magnitude of the transient load step. Next, determine what type of

output capacitors to be used. (If more than one type of output capacitor is used, select the capacitor type that

makes up the majority of the total output capacitance.) Knowing this information, use the chart in Figure 11

through Figure 16 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 the load step (in Amps). 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

TurboTrans table. The TurboTrans tables include both the required output capacitance and the corresponding

output load steps.

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

capacitance. Selecting the amount of output capacitance along the X-axis, reading up to the 'With TurboTrans'

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

As an example, let's look at a 12-V application requiring a 75 mV deviation during a 15 A, 50% load transient. A

majority of 330

µF, 10 mΩ output capacitors will be used. Use the 12 V, Type B capacitor chart, Figure 13.

Dividing 75 mV by 15 A gives 5 mV/A transient voltage deviation per amp of transient load step. Select 5 mV/A

on the Y-axis and read across to the 'With TurboTrans' plot. Following this point down to the X-axis gives us a

minimum required output capacitance of approximately 1300

µF. The required R

To see the benefit of TurboTrans, follow the 5 mV/A marking across to the 'Without TurboTrans' plot. Following

that point down shows that a minimum of 8200

µF of output capacitance is required to meet the same transient

deviation limit. This is the benefit of TurboTrans. A typical TurboTrans application schematic is shown in

Figure 17.

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