LPC4088 QuickStart Board - Integration

Page last updated 15 Oct 2013, by EmbeddedArtists AB. 0 replies

Guide and Checklist for Integration

The LPC4088 QuickStart Board has been designed with focus on integration. There is proper ESD protection on the communication interfaces (Ethernet and USB). The industrial temperature range is supported, -40 to +85 degrees Celsius.

We have created an integration checklist that is a combined guide and checklist for how to integrate the LPC4088 QuickStart Board into a design.

Besides designing the needed interfaces (especially see the How to... guides on this page), a suitable power supply must be designed.

How to Design the Power Supply

Step 1: Determine current consumption

As a first step, determine the current consumption of the LPC4088 QuickStart Board. Current consumption vary greatly depending on which application that is running on the board. Therefore it is best to measure when running the actual application and having the communication interfaces that shall be used enabled and active.

Power hungry functionalities are:

FunctionalityCurrent consumption
EthernetCan add up to 100-150 mA
USB HostCan add up to 1A if a current hungry external USB Device is connected
SDRAMTypically adds about 15-30 mA but can be more if all code is executed from SDRAM
RF-moduleCan add in the region of 50-400mA, but check the datasheet of the RF-module for details

If the LPC4088 QuickStart Board is powered via EXT_VIN (pin 2) or the HDK USB connector, it is possible to measure the voltage drop over a 0.1 ohm series resistor on JP4. 100mA consumption will result in 10mV over JP4.

Note that the power supply must be designed to handle the peak current consumption, not the mean. If no current measurements are done on the LPC4088 QuickStart Board, a power supply capable of delivering 500mA will be ok. Add 1A per USB Host channel that is active and add current consumption for any RF-module used.

Do not forget that any circuit external to the LPC4088 QuickStart Board will also add current consumption.

Step 2: Select Powering Structure

Option 1) Power the LPC4088 QuickStart Board via an external 5V power supply (feed via pin 2), 400mA + RF-module consumption + USB Host consumption. Power any external circuit with 3.3V via pin 44 and, if needed, 5V via pin 43. The external circuit can consume max 300 mA.

Option 2) Power the LPC4088 QuickStart Board via an external 5V power supply (feed via pin 2), 400mA + RF-module consumption + USB Host consumption. Leave pin 44 unconnected and feed any external circuit with 3.3V (if needed) from an external supply. This means that the LPC4088 QuickStart Board and the external circuit are powered separately.

Option 3) Power the LPC4088 QuickStart Board via an external 3.3V power supply (feed via pin 44), +-10%, 400mA + RF-module consumption. If the on-board USB Host interface is used, provide an 5V power supply (feed via pin 2).

Step 3: Design power supply

Have a look at the sample interface design schematic (the power supply example page) that have been created for the LPC4088 QuickStart Board.

  • There is a very simple +5V input design that leaves all the complexity to an external +5V DC power supply.
  • There are also two wide input range (7-30V) power supply examples that generates +5V and +3.3V, respectively. The +5V example is for powering option 1) and 2) above. The +3.3V example is for powering option 2) and 3) above.

Texas Instruments WEBENCH design tool is an excellent starting point for power supply reference designs. All power supply designs have implementation specific details have are not shown in the example schematics, like input connector, possible rectifying (of AC input), EMI and ESD protection and possible over-current/over-voltage protection.

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