TPS65166 datasheet(30/41 Pages) TI1

30 / 41 page

Setting the Output Voltage and Selecting the Feed-Forward Capacitor (Positive Charge Pump)

out

FB4

R14

= V

= 1.24 V

R15

(35)

F B4

1.24V

R15 =

2.4 k

500

(36)

out

FB4

R14 = R15

= R 15

1.24 V

(37)

C17 =

12 kHz

R14

´ p ´

(38)

Base2

Control

Logic

FB4

Error Amplifier

CurrentLimit

Softstart

1.24 V

100 mV

Shortcircuit

Comparator

Shortcircuit

Mode

55 A

8 mA

PNP Transistor Selection (Positive Charge Pump)

ONE

= 2

Vs + V

(39)

TPS65166

SLVS976 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com

To minimize noise a minimum current through the feedback divider of 500

µA is recommended. At startup the

device is in short circuit mode with reduced current (typ. 50

µA) until the feedback voltage FB4 exceeds 100 mV,

then the device switches to soft-start mode until the output voltage VONE is in regulation. Due to the high output

current and low required voltage drop, high current Schottky diodes with low forward voltage are recommended

for this regulator.

To minimize noise and leakage current sensitivity keep the lower feedback divider resistor R15 between 100

Ω

and 4.7k

Ω. See typical application section for charge pump circuit.

Across the upper feedback resistor R14, a bypass capacitor C17 is required. The capacitor is calculated as:

Figure 31. Positive Chargepump Block Diagram

The maximum possible VONE output voltage is calculated as:

With:

Vs = boost converter output voltage

VD1 = Forward voltage of boost converter Schottky diode

VD2 = Forward voltage of charge pump diode for a current of IONE / D

IONE = VONE output current

D = Duty cycle of boost converter (D = 1 – Vin / Vs)

R = Series resistor (if applicable, e.g., 2

Ω for typical application)

VQ = Transistor saturation voltage

As a general recommendation the VONE voltage level in use should be at least 0.5V lower than the calculated

maximum VONE voltage.

Submit Documentation Feedback

Product Folder Link(s): TPS65166

TPS65166 Datasheet(PDF) 30 Page - Texas Instruments

TPS65166 Datasheet(HTML) 30 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41

Datasheet Download

Link URL