BC41B143A-DS-002PD Datasheet, PDF (50/89 Pages) List of Unclassifed Manufacturers – BlueCore 4-ROM CSP EDR Single Chip Bluetooth v2.0 + EDR System

Device Terminal Descriptions
11.1.1 Transmit RF Power Control for Class 1 Applications
An 8-bit voltage DAC (AUX_DAC) can be used to control the amplification level of an external PA for Class 1
operation. The DAC output is derived from the on-chip band gap voltage reference and is virtually independent of
temperature and supply voltage. The output voltage is given by either:
V_AUX
_ DAC
=
MIN_{⎜⎜⎝⎛}
⎜⎛
⎝
3.3V
×
CNTRL _ WORD
255
⎟⎞, (VDD
⎠
_
PIO
−
0.3V )_{⎟⎟⎠⎞}
Equation 11.1: Output Voltage with Load Current ≤ 10mA
for a load current ≤10mA (sourced from the device) or:
V_{AUX _ DAC}
=
MIN_{⎜⎜⎝⎛}
⎜⎛ 3.3V
⎝
×
CNTRL _ WORD
255
⎟⎞, VDD
⎠
_
PIO _{⎟⎟⎠⎞}
Equation 11.2: Output Voltage with No Load Current
for no load current.
BlueCore4-ROM CSP enables the external PA only when transmitting. Before transmitting, the IC normally ramps
up the power to the internal PA, then it ramps it down again afterwards. However, if a suitable external PA is
used, it may be possible to ramp the power externally by driving the gain pin on the PA from AUX_DAC.
TX Power
Modulation
t_carrier
Figure 11.2: Internal Power Ramping
The PS Key PSKEY_TX_GAINRAMP controls the delay (in units of μs) between the end of the transmit power
ramp and the start of modulation. In this period the carrier is transmitted, which gives the transmit circuitry time to
fully settle to the correct frequency.
Bits [15:8] define a delay, t_carrier, (in units of μs), between the end of the transmit power ramp and the start of
modulation. In this period an unmodulated carrier is transmitted, which aids interoperability with some other
vendor equipment which is not strictly Bluetooth compliant.
BC41B143A-ds-002Pd
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© Cambridge Silicon Radio Limited 2005
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