Rf Interface; Charging Control; Digital Interface - Nokia NKC-1X Series Technical Documentation Manual

NKC-1X
System Module
between the CCP and CCN pins. In practice, the 220nF flying capacitor is formed by 2 x
100nF capacitors that are parallel to each other. The VR1A regulator is used by the Taco
RF ASIC. VR1B is not used in the NKC-1X.
The VR2 regulator is used to supply the (1) external RF parts, (2) lower band up con-
verter, (3) TX power detector module and (4) Safari. In light load situations, the VR2 reg-
ulator can be set to the low Iq-mode.
The VR3 regulator supplies the VCTCXO and Taco in the RF. It is always enabled when the
UEM is active. When the UEM is in the Sleep mode, the VR3 is disabled.
The VR4 regulator supplies the RX frontends (LNA and RX mixers).
The VR5 regulator supplies the lower band PA. In light load situations, the VR5 regulator
can be set to the low Iq-mode.
The VR6 regulator. In light load situations, the VR6 regulator can be set to the low Iq-
mode. Note: Not used in the NKC-1X.
The VR7 regulator supplies the RF synths. In light load situations, the VR7 regulator can
be set to the low Iq-mode.
The IPA1 and IPA2 are programmable current generators. A 27Ω/1%/100ppm external
resistor is used to improve the accuracy of the output current. The IPA1 is used by the
lower PA band and IPA2 is used by the higher PA band.

RF Interface

The interface between the baseband and the RF section is also handled by the UEM. It
provides A/D and D/A conversion of the in-phase and quadrature receive and transmit
signal paths. It also provides A/D and D/A conversions of received and transmitted audio
signals to and from the UI section. The UEM supplies the analog AFC signal to the RF sec-
tion, according to the UPP DSP digital control.

Charging Control

The CHACON block of the UEM asics controls charging. The needed functions for the
charging controls are the (1) pwm-controlled battery charging switch, (2) charger-moni-
toring circuitry, (3) battery voltage monitoring circuitry and (4) RTC supply circuitry for
backup battery charging (Not used in NKC-1X). In addition to these, external compo-
nents are needed for EMC protection of the charger input to the baseband module.

Digital Interface

Data transmission between the UEM and the UPP is implemented using two serial con-
nections, DBUS (programmable clock) for DSP and CBUS (1.0MHz GSM and 1.08MHz
TDMA) for MCU. The UEM is a dual voltage circuit: the digital parts are run from 1.8V
and the analog parts are run from 2.78V. The Vbat (3,6V) voltage regulators's input is
also used.
Page 12
Nokia Corporation
CCS Technical Documentation
Issue 1 02/03