Current Sharing and TurboTrans™

PTH08T255W

TERMINAL

MASTER

SLAVE

NAME

NO.

6,7,14,15

Connect to the Input Bus.

Connect to the Input Bus.

10,11

Connect to the Output Bus.

Connect to the Output Bus.

GND

8,9,12,13

Connect to Common Power GND.

Connect to Common Power GND.

Inhibit and

Use for Inhibit control & UVLO adjustments. If

21

No Connection. Leave open-circuit.

UVLO

unused leave open-circuit.

18

No Connection. Leave open-circuit.

resistor between this pin and AGND (pin 4).

Connect to the output voltage either at the load or

+Sense

17

No Connection. Leave open-circuit.

at the module (pin 11).

Connect to the output GND either at the load or at

–Sense

16

No Connection. Leave open-circuit.

the module (pin 13).

Track

20

No Connection. Leave open-circuit.

TurboTrans™

19

No Connection. Leave open-circuit.

and +Sense (pin 17).

Connect to an external clock. If unused connect to

SmartSync

22

Connect to Common Power GND.

GND.

CONFIG

1

Connect to the Input Bus.

Share

2

Connect to pin 2 of Master.

Comp

3

Connect to pin 3 of Master.

AGND

4

Connect to pin 4 of Master.

CLKIO

5

Connect to pin 5 of Master.

(1)

For more details on the pin descriptions, please refer to the 'Terminal Functions' described in Table 1

(2)

See Layer A in Figure 22 for recommended layout

(3)

See Layer B in Figure 22 for recommended layout

TurboTrans pin (pin 19) of the Master module to the +Sense pin (pin 17) of the Master module. When paralleling

the TurboTrans Selection section, however the values must be calculated for a single module. Therefore, the

value as explained in the TurboTrans Selection section. The value of output capacitance calculated is the

output capacitance. The TurboTrans pin of the Slave module must be left open.

As an example, let's look at a 12-V application requiring a 40 mV deviation during a 20 A load transient. A

majority of 470

µF, 10 mΩ output capacitors are used. Use the 12 V, Type B capacitor chart, Figure 7. First,

halving the load transient gives 10 A. Dividing 40 mV by 10 A gives 4 mV/A transient voltage deviation per amp

of transient load step. Select 4 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 1800

µF. This is the

minimum required output capacitance per module. Hence, the total minimum output capacitance would be 2 ×

1800

µF = 3600 µF. The required R

Copyright © 2008, Texas Instruments Incorporated

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