Figure 15. Top and power

Block Diagram Overview

This section illustrates the high-level connections between major components of the development board.

Interconnected Modules:

• U_Connectors: Interfaces with various MCU pins (PA[0..15], PB[0..15], PC[0..15], PD[0..15], PE[0..15], PF[0..15], PG[0..15], PH[0..2]).
• U_MCU_144: The central microcontroller unit, featuring interfaces like COMP2_INP, BOOT0, NRST, TCK, TMS, SWO, STLK_RX, STLK_TX, MCO, and PWR_ENn.
• U_ST_LINK_V2-1: Debugging and programming interface, connected to the MCU via control and communication signals.
• U_USB: Universal Serial Bus interface, including signals for data (DP, DM), power (VBUS), identification (ID), and control (Disconnect, PowerSwitchOn, OverCurrent, VBUS_DET).
• U_Ethernet: Ethernet interface utilizing the RMII (Reduced Media-Independent Interface) standard, with signals such as TX_EN, TXD0, TXD1, RXD0, RXD1, CRS_DV, MDC, MDIO, and REF_CLK.

The diagram shows how these modules are interconnected, with the MCU acting as the central hub for communication and control across these interfaces.

Detailed Schematic - Power and Control

This section details the power supply circuitry, including voltage regulation, power switching, and indicator LEDs.

Power Supply Circuitry:

• Input Voltage (VIN_5V): Connected to a 5V voltage regulator, U5 (LD1117S50TR), which outputs a regulated +5V. This stage includes capacitors C17 (10uF/25V) and C18 (10uF) for stability.
• +5V Rail: The primary 5-volt power rail.
• Power Switch (ST890CDR): Manages the +5V supply derived from the STLINK USB connection. It features control pins (ON, FAULT, SET) and is protected/indicated by a green LED (LD6) through a 1kΩ resistor (R29). A 2.7kΩ resistor (R28) is used for setting the power switch behavior.
• +3V3 Rail: A 3.3-volt power rail generated by a second voltage regulator, U6 (LD39050PU33R), which takes input from the +5V rail. This regulator is supported by multiple capacitors (C11, C16, C19, C20, C22, C23) and has status pins (EN, PG, NC).

Key Components:

• Voltage Regulators: U5 (LD1117S50TR), U6 (LD39050PU33R).
• Power Switch IC: ST890CDR.
• Resistors: R21 (1kΩ), R27 (10kΩ), R29 (1kΩ), R28 (2.7kΩ).
• Capacitors: C11 (100nF), C16 (4.7uF), C17 (10uF/25V), C18 (10uF), C19 (100nF), C20 (1uF_X5R_0603), C22 (100nF), C23 (1uF_X5R_0603).
• LED Indicators: LD5 (Red), LD6 (Green).
• Jumpers/Connectors: JP3 (Header 3x2), JP5.
• Shorting Blocks/Fuses: SB1 (Open), SB2 (Closed), SB3 (Closed).

Schematic Notes:

1. Text in italics on a wire is for signal identification, not a net name.
2. Add C58 (4.7uF ceramic) on VDD from A-01 to B-01.
3. R33 value changed to 200kΩ from A-01 to B-01.
4. Add pull-up & pull-down resistors on PB2 for BOOT1 (F4 series) from A-01 to B-01.
5. All peripherals' power changed to +3V3_PER from A-01 to B-01.
6. C35 & C36 values changed to 2.7pF from A-01 to B-01.
7. Add R76 (1.5kΩ) pull-up circuit to USB_DP for F303ZE only from A-01 to B-01.
8. LD1 can be controlled by PB0 from A-01 to B-01.
9. D11 on CN7 can be set to PB5 from A-01 to B-01.

Document Information:

Title: TOP & POWER

Project: NUCLEO-XXXXZX

Reference: MB1137

Revision: B-01

Date: 8/19/2016

Sheet: 1 of 6

Manufacturer: STMicroelectronics (indicated by ST logo)