User manual

LPC4357 Developer’s Kit - User’s Guide

Page 37

4.23 SP13: Power Supply

The power supply on the board is straight forward. There are three powering sources:

1. +5V DC via 2.1mm power jack (J24). Center pin positive. There is also an alternative

connector (J23) for this powering option.

2. USB powering via the USB-to-UART Bridge connector (J25).

3. +5V DC power form the PoE (Power-over-Ethernet) connector (J12).

In all cases, a stable +5V DC voltage powers the board. Current consumption depends on USB Host

usage. If USB Host is not used (or used with very low external current consumption), a 1 Amp power

supply (5W) is all what is needed. If USB Host is used with high external current consumption a 2-2.5

Amp power supply (10-12.5W) is needed.

The second powering option, via the USB-to-UART connector will work in most cases. Note however

that not all PC:s and laptops can provide this amount of current. An external USB Hub can be used in

that case or an external power supply.

U21 is a 1.5A +3.3V linear regulator. LED36 signals presence of regulated +3.3V. Three voltage

measurement pads exist for verifying correct voltage levels on the board. See picture below for

locating relevant components. The table below lists signal connections.

Figure 24 – Power Supply

4.24 SP14: LCD Expansion Interface

The board contains a buffered LCD expansion interface via a 50 pos IDC connector. The expansion

interface also includes UART (see UART multiplexing), I2C and SPI interfaces. These additional

interfaces are for identifying external displays (via configuration I2C-E2PROM) as well as touch screen

controllers. An external LCD pixel clock can also be supplied via the expansion connector.

The LCD expansion connector carries 18 data bits per pixel by default. (6 per RGB color). The

LPC4350 LCD controller can produce 24 data bits per pixel and it is possible to output all these signals

on the LCD expansion connector. The trade-off is that the UART and I2C serial interfaces have to be

removed. Via SJ6-SJ11 it is possible to select what signals to make available on the LCD expansion

connector. By default pad 1-2 are connected on SJ6-SJ11.

Voltage Measuring Pads

Left-to-right:

GND, +5V, +3.3V

Power Supply Input

J24

Power Supply Input

J23

+3.3V LED

LED36

USB mini-B Connector

J25

PoE Connector

J12, pin 1 leftmost