Datasheet

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FUNCTIONAL OVERVIEW
TPS65810
TPS65811
SLVS658B – MARCH 2006 – REVISED FEBRUARY 2007
Table 10. ADC input channel overview
Channel Connection Parameter Sampled Voltage Range Under Special Features Full Scale Reading LSB
Normal Operating (Internal reference value
Conditions selected )
CH1 ANLG1 pin User defined User defined Internal pullup current 2.535 V Full scale
source programmable reading
CH2 ANLG2 pin 2.535 V
via I
2
C: 0/ 10/50/60 µ A ÷ 1023
CH3 ISET1 pin Voltage proportional to 0 V (charger off) to — 2.535 V
charge current 2.525 V (fast charge)
CH4 TS pin Voltage proportional to pack 0 V (short) to 4.7V (no No internal pullup 2.535 V
temperature thermistor) current, use external
pullup resistor to bias
pack thermistor
CH5 Internal Voltage proportional to IC 1.85 V at T
J
= 25 ° C, — 2.535 V
junction junction temperature – 6.5 mV/ ° C slope typ
temperature
CH6 RTC_OUT Internal LDO output voltage 0 V to 3.3 V — 4.7 V
pin
CH7 OUT pin System Power bus voltage 0 V to 4.4 V — 4.7 V
CH8 BAT pin Battery pack positive 0 V to 4.4 V — 4.7 V
terminal voltage
The TPS65810 ADC can be subdivided in four sections:
1. Input selection: The input selection section has two major blocks, the input bias control and an 8 channel
MUX. The input bias control provides the bias currents that are applied to pins ANLG1 and ANLG2. The bias
currents for pins ANLG1 and ANLG2 are set on I
2
C register ADC_WAIT.
The ANLG1 pin current source is automatically enabled when the input power is detected, providing the
required setup to measure a battery ID resistor (ANLG1 pin). ANLG1 and ANLG2 can be used to measure
external resistive loads or analog voltages. The bias current sources are always connected to the OUT pin
internally.
The internal MUX connects one of the monitored analog inputs to the ADC engine, following the selection
defined on register ADC_SET.
2. ADC engine: The ADC engine uses an internal or external voltage reference, as defined by the ADC_REF
bit on the ADC_SET control register. If the internal reference is selected ADC_REF is connected to an
internal LDO that regulates the ADC_REF pin voltage to generate the ADC supply and internal voltage
reference. The internal LDO maximum output current is 6 mA typical, and a conversion should be started
only after the external capacitor is fully charged.
If an external reference is used it should be connected to the ADC_REF pin. When an external reference is
selected the internal LDO connected to ADC_REF is disabled. Care must be taken when selecting an
external reference as the ADC reference voltage, as it affects the ADC LSB absolute value.
3. Trigger control and synchronization: The ADC engine starts a conversion of the selected input when the
trigger control circuit sends a start command. The trigger control circuit starts the ADC conversion and
transfers the ADC output data to the arithmetic logic unit (ALU) at the end of the conversion. It also
synchronizes the data transfer from the ALU to the I
2
C ADC_READING register at the end of a conversion
cycle, and generates the ADC status information sent to the ADC registers.
An ADC engine conversion is triggered by the TPS65810 trigger control circuit using either an internal trigger
or an external trigger. The internal trigger is automatically generated by the TPS65810 at the end of each
ADC engine conversion, following the timing parameters set on I
2
C registers ADC_SET, ADC_DELAY and
ADC_WAIT.
The GPIO3 pin can be used as an external trigger if the bit ADC_TRG_GPIO3 is set HI, in the I
2
C register
ADC_DELAY. In the external trigger mode a new conversion is started after the GPIO3 pin has an edge
transition, following the timing parameters set on I
2
C registers ADC_SET, ADC_DELAY and ADC_WAIT.
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