ONE

s

ONE

D2

ONE

I

Power dissipation = 2

V

V

2

V

R

I

D

æ

ö

´

-

-

´

-

´

´

ç

÷

è

ø

(40)

Resistor R12 Function and Power Dissipation (Positive Charge Pump)

2

resistor

ONE

P

= R12

I

´

(41)

Output Capacitor Selection (Positive Charge Pump)

TPS65166

Because of the 1

µF collector capacitor C16 a wide range of transistors can be used. The most important

for calculation. See Table 13 for possible transistor selection.

Table 13. Transistor Selection (Positive Charge Pump)

TRANSISTOR

PZT2907A

KTA1552T

KTA1718D

KTA1666

R12 is used to limit the peak current flowing from collector capacitor C16 through R12, D3 and C15 into the

ripple. The power dissipation for the resistor R12 can be calculated by following formula:

For the best output voltage filtering, low ESR ceramic output capacitors are recommended. Two 4.7

µF ceramic

output capacitors with sufficient voltage rating are adequate for most applications. Additional capacitors can be

added to improve the load transient regulation. See Table 14 for capacitor selection.

Table 14. Output Capacitor Selection (Positive Charge Pump)

CAPACITOR

COMPONENT SUPPLIER

4.7

µF/50V

Murata, GRM31CR71H475KA12

4.7

µF/50V

Taiyo Yuden, UMK316BJ475KL-T

Copyright © 2009, Texas Instruments Incorporated

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