Nokia 1508 Manual page 7

1508(RM-388)
Baseband Description and Troubleshooting
The interface of the CBP5.6 is described in the following diagram.
Receive and transmit interfaces for CBP 5.6 provide analog I and Q
signals and support super-heterodyne radio and direct conversion
radio design. The CP external-memory interface supports 3.0V or
1.8V, the address bus supports 16-bit address which can support
three to six external devices via chip selects. CBP 5.6 includes 48
GPIOs and interrupts, some of which are multiplexed with other
functions. All GPIO pins are in input state by default and use a large
pull-up or pull-down resistor value to minimize the current drain. The
USB port supports data rates of up to 12Mbps, the USB analog
drivers and 48.00MHz PLL are integrated into CBP 5.6, the control
processor manages the USB function. Two independent serial-
peripheral interfaces are provided on CBP 5.6: one is for RF control
and the other is for general-purpose use. The R-UIM interface
supports 3V UIM cards and consists of five pins, these pins are
multiplexed with another function. The CP manages the R-UIM
function.
Five independent PDM DACs are supplied on the CBP 5.6 chip.
Three of the outputs are dedicated to radio-control signals for Rx
automatic gain control (AGC), Tx AGC, and automatic frequency
control (AFC). The fourth and fifth PDM outputs are spares. The
PDMs are 12-bit DACs and have a guaranteed output range of 0.2 V
to 2.5 V.
The 12-bit auxiliary ADC supports eight independent external
channels on pins AUXADC [7:0]. There are also eight internal
channels used to measure internal analog voltages. The input
voltage range is 0.2 V to 2.7 V. The conversion time is 156 µsec. The
typical uses of the external auxiliary ADC channels include: Tx RF
power measurement, battery voltage, and temperature sensors.
The baseband is powered by the following PMU ACT5805 regulators:
VDD_DIG = 3.0v
VDD_CORE = 1.8v
VDD_TXPLL = 2.85v
VDD_TCXO = 2.85v
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