TLV320AIC26
SLAS412 DECEMBER 2003
www.ti.com
32
VBAT
10 k
DC/DC
Converter
VDD
+
Battery
2 k
GND
Figure 28. Battery Measurement Functional Block Diagram
For increased protection and robustness, TI recommends a minimum 100-
resistor be added in series between the
system battery and the VBAT pin. The 100-
resistor causes an approximately 1% gain change in the battery voltage
measurement, which can easily be corrected in software when the battery conversion data is read by the operating system.
See the Conversion Time Calculation for the ’AIC26 section in this data sheet for timing diagrams and conversion time
calculations.
Auxiliary Measurement
The auxiliary voltage input (AUX) can be measured in much the same way as the battery inputs. Applications might include
external temperature sensing, ambient light monitoring for controlling the back-light, or sensing the current drawn from the
battery. The auxiliary input can also be monitored continuously in scan mode.
See the Conversion Time Calculation for the ’AIC26 section in this data sheet for timing diagrams and conversion time
calculations.
Port Scan
If making measurements of BAT1, BAT2, and AUX is desired on a periodic basis, the port scan mode can be used. This
mode causes the ’AIC26 to sample and convert both battery inputs and the auxiliary input. At the end of this cycle, the
battery and auxiliary result registers contain the updated values. Thus, with one write to the ’AIC26, the host can cause
three different measurements to be made.
See the Conversion Time Calculation for the ’AIC26 section and the Port Scan Operation subsection in this data sheet for
timing diagrams and conversion time calculations.
Hardware Reset
The device requires a low-to-high pulse on RESET after power up for correct operation. A hardware reset pulse initializes
all the internal registers, counters, and logic.
Hardware Power Down
By default the PWD/ADWS pin is configured as a hardware power-down (active low) signal. The device powers down all
the internal circuitry to save power. All the register contents are maintained. Some counters maintain their value. The user
can optionally use this pin as ADWS (ADC word select) by register programming.