BC352239A Datasheet, PDF (99/116 Pages) List of Unclassifed Manufacturers – BlueCore 3-Multimedia External

Device Terminal Descriptions
8.13 Power Supply
8.13.1 Voltage Regulator
An on-chip linear voltage regulator can be used to power the 1.8V dependent supplies. It is advised that a
smoothing circuit using a 2.2µF low ESR capacitor and 2.2Ω resistor be placed on the output VDD_ANA adjacent
to VREG_IN.
The regulator is switched into a low power mode when the device is sent into deep sleep mode. When the on
chip regulator is not required VDD_ANA is a 1.8V input and VREG_IN must be either open circuit or tied to
VDD_ANA.
8.13.2 Sequencing
It is recommended that VDD_CORE, VDD_RADIO, VDD_LO and VDD_ANA be powered at the same time. The
order of powering supplies for VDD_CORE, VDD_PIO, VDD_PADS and VDD_USB is not important. However if
VDD_CORE is not present, all inputs have a weak pull-down irrespective of the reset state.
8.13.3 Sensitivity to Disturbances
It is recommended that if you are supplying BlueCore3-Multimedia External from an external voltage source that
VDD_LO, VDD_ANA and VDD_RADIO should have less than 10mV rms noise levels between 0 to 10MHz.
Single tone frequencies are also to be avoided. A simple RC filter is recommended for VDD_CORE as this
reduces transients put back onto the power supply rails.
The remaining supplies VDD_MEM, VDD_PIO, VDD_PADS and VDD_USB can be connected together with the
VREG_IN to the 3.3V supply and simply decoupled as shown in Figure 11.10.1.
The transient response of the regulator is also important. At the start of a packet, power consumption will jump to
high levels, see average current consumption section. The regulator should have a response time of 20µs or
less, it is essential that the power rail recovers quickly.
BC352239A-ds-001Pc
© Cambridge Silicon Radio Limited 2004
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