Specifications

26
5. POWER CONTROL
5.1 Power Supply Configuration
WT32 contains an internal battery charger and a switch mode regulator that is mainly used
for internal blocks of the module. The module can be powered from a single 3.3 V supply
provided that VDD_CHG is floating. Alternatively the module can be powered from a
battery connected to VDD_BAT and using an external regulator for VDD_IO. 1.8 V to 3.3 V
supply voltage for VDD_IO can be used to give desired signal levels for the digital
interfaces of the module. USB, however, requires 3.3 V for proper operation and thus,
when USB is in use, 3.3 V for VDD_IO is mandatory.
AIO pins of the module use 1.8 V from the internal regulator and thus voltage level with
these pins is within 0 V and 1.8 V.
VDD_BAT
Switch mode 1,8 V
regulator
VDD_IO
Battery Charger
In
Out
VDD_CHG
AIO
Audio
RF
Flash
PIO
USB
UART
PCM
VREG_ENA
Figure 5: Power supply configuration of WT32
5.2 Voltage Regulator Enable Pin
The regulator enable pin VREG_ENA is used to enable WT32. VREG_ENA enables the on-
chip switched mode regulator.
VREG_ENA is active high, with a logic threshold of around 1V, and it has weak pull-down.
It can tolerate voltages up to 4.9V, so it may be connected directly to a battery to enable
the device.
VREG_ENA can be configured with iWRAP to either latch on/off the internal regulators at
the rising edge of the input voltage, or to latch the regulators on at the rising edge and
shut down the regulators at the falling edge. Following figure shows an example of how to
to implement a power on/off button using the latch feature. See iWRAP user guide for the
details on configuration.