adc101c027cimkx National Semiconductor Corporation, adc101c027cimkx Datasheet - Page 29

• Manufacturer Part Number: adc101c027cimkx
• Description: I2c-compatible, 12-bit Analog-to-digital Converter Adc With Alert Function
• Manufacturer: National Semiconductor Corporation

2.3 INTELLIGENT BATTERY MONITOR
The ADC101C021 is easily used as an intelligent battery
monitor. The simple circuit shown in Figure 20, uses the
ADC101C021, the LP2980 fixed reference, and a resistor di-
vider to implement an intelligent battery monitor with a window
supervisory feature. The window supervisory feature is im-
plemented by the "out of range" alert function. When the
battery is recharging, the Over Range Alert will indicate that
the charging cycle is complete (see Figure 21). When the
battery is nearing depletion, the Under Range Alert will indi-
cate that the battery is low (see Figure 22).
FIGURE 20. Intelligent Battery Monitor Circuit
FIGURE 22. Discharge Cycle
FIGURE 21. Recharge Cycle
30052078
30052079
30052077
29
In addition to the window supervisory feature, the
ADC101C021 will allow the controller to read the battery volt-
age at any time during operation. Reading the conversion
result via the I
ing.
The accurate voltage reading and the alert feature will allow
a controller to improve the efficiency of a battery-powered
device. During the discharge cycle, the controller can switch
to a low-battery mode, safely suspend operation, or report a
precise battery level to the user. During the recharge cycle,
the controller can implement an intelligent recharge cycle,
decreasing the charge rate when the battery charge nears
capacity.
2.3.1 Trickle Charge Controller
While a battery is discharging, the ADC101C021 can be used
to control a trickle charge to keep the battery near full capacity
(see Figure 23). When the alert output is active, the battery
will recharge. An intelligent recharge cycle will prevent over-
charging and damaging the battery. With a trickle charge, the
battery powered device can be disconnected from the charger
at any time with a full charge.
2
C interface provides an accurate voltage read-
FIGURE 23. Trickle Charge
www.national.com
30052080