Specifications

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Figure 6: Example of how to make a power on/off button using latch feature of the
internal regulators
In figure 6 the internal regulators are latched on at the rising edge, i.e when pressing
SW1. One of the PIOs is configured to power hold thus keeping the external regulator on
until shut down by pressing SW1 again.
5.3 Battery Charger
The battery charger is a constant current / constant voltage charger circuit, and is suitable
for lithium ion/polymer batteries only. It shares a connection to the battery terminal,
VDD_BAT, with the switch-mode regulator. The charger is initially calibrated by Bluegiga
Technologies to have V
float
= 4.2 V.
The constant current level can be varied to allow charging of different capacity batteries.
The charger enters various states of operation as it charges a battery. These are shown
below:
 Off: entered when the charger is disconnected.
 Trickle Charge: entered when the battery voltage is below 2.9V.