AN10220 describes how to use Philips LPC900 microcontrollers in 5V environments. The LPC900 series microcontrollers operate at 3V, but the I/O pins support 5V. To use LPC900 in a 5V system, consider the following aspects: 1. Power the LPC900 with a 5V supply and connect the inputs and outputs to 5V logic levels. 2. Use external circuits to provide higher voltages and currents above Vdd for external loads.
The note describes the LPC900 family, which operates from 2.4 V to 3.6 V, and explains how to adapt it for 5 V environments. It covers power‑supply options, such as using an LED drop or an LDO regulator, and the current consumption limits of the devices.
The document details the I/O characteristics: pins are 5 V‑tolerant, can source up to +20 mA or sink up to -3.2 mA, and include bi‑directional, push‑pull and open‑drain modes. It also provides guidance on interfacing inputs and outputs to 5 V logic families and driving external loads.
| Supply voltage range | 2.4 V to 3.6 V |
|---|---|
| Maximum supply current | 25 mA from 3 V supply |
| I/O source current | +20 mA |
| I/O sink current | -3.2 mA |
| Input leakage current | < 10 µA |
| 5 V tolerance of I/O pins | Yes (except two pins) |
No, the LPC900 is specified to work from 2.4 V to 3.6 V, though its I/O pins are 5 V‑tolerant.
Each I/O pin can source up to +20 mA.
Yes, all I/O pins are 5 V‑tolerant except two pins used for reset.