UM1551 datasheet(3/17 Pages) STMICROELECTRONICS

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UM1551

Description

Quick guide and default configuration

By default, the board is powered from a USB host (notebook, PC, docking station, etc.)

through the J2 USB connector. No external power supply is necessary.

In this mode, evaluation of all STCC50x1 device features is possible with the following

limitation:

Maximum charging current is limited by the USB host capabilities (typically 500 mA

to 2000 mA).

Jumper and selector settings for default configuration

J5: ON (closed)

SW6: VEXT (1 - 2)

Settings and connections

Variable resistors

Resistor R18

This resistor adjusts the VLDO voltage to verify proper functionality of the attach detector for

the whole VDD operating range. The equation is as follows:

Equation 1

Minimum adjustable voltage is approx. 1.7 V, maximum voltage is close to VEXT. The VLDO

increases in a counter-clockwise direction.

For externally set VDD voltage, the jumper selector SW6 can be placed in the VEXT position,

connecting VEXT directly to VDD.

Resistor R26

This resistor adjusts the current limiter threshold according to Equation 2:

Equation 2

Minimum current is approx. 400 mA, maximum current is approx. 2700 mA. The current limit

increases in a clockwise direction.

For minimum current, the accuracy is not defined. The host/power supply capability may be

at least equal to the current limiter threshold set by R26.

VLDO

1,2 R18 6,2 15



----------------------------------------------------- Vk







ISC

48000

R26 18

------------------------ mA k







UM1551 Datasheet(PDF) 3 Page - STMicroelectronics

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