User's Manual

Bluegiga Technologies Oy
Page 40 of 52
15 Power Control and Regulation
LDO 3V3 LDO 1V8 LDO 1V35
VBUS (4.25V – 5.75V)
VREG_IN_HV
(3.3V OUT / 2.3V – 4.8V IN)
VREG_OUT_HV
1.8V OUT / 1.7V – 1.95V IN
VREG_EN_RST#
LDO 1V35
LDO 1V25
Figure 29: Internal regulators and powering of BT111
15.1 Voltage Regulator Enable
All the regulators are enabled, except the USB linear regulator, by taking the VREG_EN_RST# pin above 1V.
Also the BT111 firmware automatically controls the regulators.
Important Note:
VREG_EN_RST# should not be taken high before the supply on VREG_IN_HV is present.
The VREG_EN_RST# pin is connected internally to the reset function and is powered from VDD_PADS, so do
not apply voltages above VDD_PADS to the VREG_EN_RST# pin. The VREG_EN_RST# pin is pulled down
internally.
15.2 USB Linear Regulator
The integrated USB LDO linear regulator is available as a 3.30V supply rail and is intended to supply the USB
interface and the high-voltage linear regulator. The input voltage range is between 4.25V and 5.75V. The
maximum current from this regulator is 150mA.
This regulator is enabled by default. If the USB linear regulator is not required leave its input (VREG_IN_USB)
unconnected.
15.3 High Voltage Linear Regulator
The integrated high-voltage linear regulator is available to power the main 1.8V supply rail. The input voltage
range is between 2.3V and 4.8V. The maximum current from this regulator is 100mA.
Take VREG_EN_RST# high to enable this regulator.
Important Note:
VREG_EN_RST# should not be taken high before the supply on VREG_IN_HV is present.
If this regulator is not required then leave VREG_IN_HV unconnected or tied to VREG_OUT_HV.