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TPS61193-Q1

SNVSAC7 – OCTOBER 2015

www.ti.com

300 m

Ω for good efficiency.

See detailed information in Texas Instruments Application Report Understanding Boost Power Stages in Switch

Mode Power Supplies (SLVA061). Power Stage Designer™ Tool can be used for the boost calculation:

http://www.ti.com/tool/powerstage-designer.

8.2.1.2.2

Output Capacitor Selection

DC-bias effect can reduce the effective capacitance by up to 80%, which needs to be considered in capacitance

value selection. Capacitance recommendations for different switching frequencies are shown in Table 2. To

minimize audible noise of ceramic capacitors their physical size should typically be minimized.

8.2.1.2.3

Input Capacitor Selection

effect can reduce the effective capacitance by up to 80%, which needs to be considered in capacitance value

selection. Capacitance recommendations for different boost switching frequencies are shown in Table 2.

8.2.1.2.4

LDO Output Capacitor

A ceramic capacitor with at least 10-V voltage rating is recommended for the output capacitor of the LDO. The

DC-bias effect can reduce the effective capacitance by up to 80%, which needs to be considered in capacitance

value selection. Typically a 1-µF capacitor is sufficient.

8.2.1.2.5

Diode

A Schottky diode should be used for the boost output diode. Do not use ordinary rectifier diodes because slow

switching speeds and long recovery times degrade the efficiency and the load regulation. Diode rating for peak

repetitive current should be greater than inductor peak current (up to 3 A) to ensure reliable operation in boost

mode. Average current rating should be greater than the maximum output current. Schottky diodes with a low

forward drop and fast switching speeds are ideal for increasing efficiency. Choose a reverse breakdown voltage

of the Schottky diode significantly larger than the output voltage.

8.2.1.3 Application Curves

Load 3 strings, 8 LEDs per string

Load 3 strings, 8 LEDs per string

Figure 19. Boost Efficiency

Figure 20. System Efficiency

22

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