TPS54623

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SLVSB09

– SEPTEMBER 2011

Figure 17. TPS54623 Operation In Current Mode

Figure 18. TPS54623 Operation In Pulse Skipping Mode

VIN and Power VIN Pins (VIN and PVIN)

The device allows for a variety of applications by using the VIN and PVIN pins together or separately. The VIN

pin voltage supplies the internal control circuits of the device. The PVIN pin voltage provides the input voltage to

the power converter system.

If tied together, the input voltage for VIN and PVIN can range from 4.5V to 17V. If using the VIN separately from

PVIN, the VIN pin must be between 4.5V and 17V, and the PVIN pin can range from as low as 1.6V to 17V. A

voltage divider connected to the EN pin can adjust the either input voltage UVLO appropriately. Adjusting the

input voltage UVLO on the PVIN pin helps to provide consistent power up behavior.

Voltage Reference

The voltage reference system produces a precise

±1% voltage reference over temperature by scaling the output

of a temperature stable bandgap circuit.

Adjusting the Output Voltage

The output voltage is set with a resistor divider from the output (VOUT) to the VSENSE pin. It is recommended to

use 1% tolerance or better divider resistors. Referring to the application schematic of Figure 31, start with a 10

k

Ω for R6 and use Equation 1 to calculate R5. To improve efficiency at light loads consider using larger value

resistors. If the values are too high the regulator is more susceptible to noise and voltage errors from the

VSENSE input current are noticeable.

Copyright

© 2011, Texas Instruments Incorporated

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