A/D Channels - Nokia NHM-7 series Service Manual

NHM–7
PAMS Technical Documentation
System Module & UI
the DSP. During this reset phase the UEM forces the VCTCXO regulator
on regardless of the status of the sleep control input signal to the UEM.
The FLSRSTx from the ASIC is used to reset the flash during power up
and to put the flash in power down during sleep. All baseband regulators
are switched on at the UEM power on except SIM and VFLASH2 regula-
tors which are controlled by the MCU. The UEM internal watchdogs are
running during the UEM reset state, with the longest watchdog time se-
lected. If the watchdog expires the UEM returns to power off state. The
UEM watchdogs are internally acknowledged at the rising edge of the
PURX signal in order to always give the same watchdog response time to
the MCU.

A/D Channels

The UEM contains the following A/D converter channels that are used for
several measurement purpose. The general slow A/D converter is a 10 bit
converter using the the UEM interface clock for the conversion. An inter-
rupt will be given at the end of the measurement.
The UEM's 11–channel analog to digital converter is used to monitor
charging functions, battery functions, voltage levels in external accessory
detection inputs, user interface and RF functions.
When the conversion is started the converter input is selected. Then the
signal processing block creates a data with MSB set to '1' and and others
to '0'. In the D/A converter this data controls the switches which connect
the input reference voltage (VrefADC) to the resistor network. The gener-
ated output voltage is compared with the input voltage under measure-
ment and if the latter is greater, MSB remains '1' else it is set '0'. The fol-
lowing step is to test the next bit and the next...until LSB is reached. The
result is then stored to ADCR register for UPP to read.
The monitored battery functions are battery voltage (VBATADC), battery
type (BSI) and battery temperature (BTEMP) indication.
The battery type is recognized through a resistive voltage divider. In
phone there is a 100kOhm pull up resistor in the BSI line and the battery
has a pull down resistor in the same line. Depending on the battery type
the pull down resistor value is changed. The battery temperature is mea-
sured equivalently except that the battery has a NTC pull down resistor in
the BTEMP line.
KEYB1&2 inputs are used for keyboard scanning purposes. These inputs
are also routed internally to the miscellaneous block. In NHM–7 KEYB1
input is used for flip detection.
The HEADINT and HOOKINT are external accessory detection inputs
used for monitoring voltage levels in these inputs. They are routed inter-
nally from the miscellaneous block and they are connected to the convert-
er through a 2/1 multiplexer.
The monitored RF functions are PATEMP and VCXOTEMP detection. PA-
TEMP input is used to measure temperature of the RFIC, Hagar. VCXO-
TEMP is not used in NHM–7.
E Nokia Corporation
Page 23
Issue 1 10/2001