ST ST7260E2, Руководство пользователя

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Getting started UM0497
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1.2.5 Supply generation circuit for the USB controller
Figure 4 shows L6920-based supply generation circuit for the USB controller. USB_SUPPLY
is the output voltage and VREG (output voltage of the power selector circuit as in
Section 1.2.4 ) is the input voltage of this circuit. The output voltage USB_SUPPLY is
programmable. In the evaluation board it is set at 4.5 voltage and depends on the ratio
R4/R9. Please refer to the L6920 datasheet for more details.
Figure 4. Supply generation circuit for the USB controller
LED (D4) is used to show the status of the input supply availability which glows whenever
the input supply falls below a certain threshold (determined by the voltage at LBI).
1.2.6 Supply shutdown control circuit for the USB controller
The STM1061 as shown in Figure 4 is used to control the shutdown operation of the L6920.
It puts the L6920 in shutdown mode whenever the input supply voltage falls below 2.5 V.
1.2.7 Jumpers and connectors
The following important jumpers control the operation of the evaluation board and are
explained according to their applications:
J2, JP1, JP3, JP12, JP13, JP14 and JP16 are used to select between the USB controller
available on the evaluation board and the external USB controller.