6 Reference Design

AN1775

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6

Reference Design

6.1

Main

This reference design is based on the STR710FZ2T6, a highly integrated microcontroller,

of embedded flash, 64 Kbytes of high speed SRAM, and numerous on-chip peripherals

.

6.1.1

Clock

●

+3.3 V surface mounted 16 MHz oscillator provides the main clock source: S113, please

refer to Section 2.1 on page 6 for more details.

●

RTC real-time clock for wakeup from standby mode with 32 KHz crystal: Y101

refer to Section 2.2 on page 6 for more details.

6.1.2

Reset

One push button S112 is used to generate a hardware reset, please refer to Section 3 on page

9 for more details.

6.1.3

Boot mode

Three switches S108, S109 and S110 are used to select the boot Mode, please refer to

6.1.4

Wake-Up

S111 push button is used to exit from STANDBY mode (power supply voltage removed except

Real time Clock).

For more details, please refer to the STR71x reference manual.

6.2

Power supplies

Power to the board is supplied using a power supply providing 5 V DC to the board. All other

required voltages are provided by the on-board voltage regulator 3V3 LD1085V33 and Zener

Diode LM4040 for ADC input voltage.

For more details, refer to LD1085V33, LM4040 datasheets and Section 1 on page 4.

6.3

USB full speed interface

USB full speed interface device supported via type B connector. The USB clock uses a

separate 48 MHz oscillator.

A transistor circuit is used to indicate the cable status (Cable connected USB/IND pin = 0 logic,

Cable deconnected = USB/IND pin = 1 logic).