UM11082
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© NXP B.V. 2018. All rights reserved.
User Manual
Rev. 1.1 — 12 January 2018
15 of 18
NXP Semiconductors
LPC8N04 Development Board
User Manual
6. Power supplies and batteries
This section describes various ways to power the Development Board. The Board can be
power distribution is shown in
Figure 8
. The LPC11U35 Debug Probe (and its associted
LEDs) can only be powered by USB, but the rest of the circuitry can be powered by USB,
one of the two button cells, the SWD connector or by using energy harvesting from an
off-board NFC antenna. Two battery options are provided; Coin cell A (DP Section) is
provided for demo applications that use the LED array. Coin cell B (MP section) is
provided for use cases where the MP section has been separated from the DP section.
A power switch is provided on the MP section of the board to prevent inadvertent draining
of the batteries when the Board is not in use; note that energy harvesting can still operate
when the power switch is set in the off position.
Protection diodes are provided to prevent reverse powering of the coin cell batteries or
external debug probe.
6.1 Measuring power consumption
Due to LED array and power amplifier circuits on the DP section of the board, it is
necessary to separate the MP section of the board before attempting accurate power
consumption measurements. Once the sections are separated, an ammeter may be
connected in series with the power supply providing powe rto the P4 or P6 headers.
7. Other board features
This section describes other board features not detailed elsewhere in this document.
7.1 User button
The User button (S2) is for general purpose use by LPC8N04 applications. It is connected
from 3.3V to LED row 5 via a 1k ohm resistor to the LPC8N04 PIO0_0 pin.
Fig 8.
LPC8N04 Development Board power supplies
5V from USB
LDO 3.3V
LPC11xx
3.3V_USB_ON ( Only On with USB )
LPC11xx LEDs
Coin Cell A
3.3V_CC_USB ( On with Coin Cell A or USB )
LPC8N04 LEDs
LPC8N04
Buzzer
Connector
3.3V_CCAandB_USB
Coin Cell B
Power Switch
LPC8N04
NFC Antenna
DP Board
MP Section
LPC8N04 SWD
3.3V
3.3V_LPC11
V_BAT
VCC
VCC
