Datasheet

V
IN
SCL
SDA
ADDR
V
A
ADC101C027
0.1 PF
GND
4.7 PF
R
1
INPUT
Unregulated
Supply
+
-
LMP7731
R
2
LM4132
4.7 PF
R
S
C
S
V
IN
SCL
SDA
V
A
ADC101C021
0.1 PF
GND
4.7 PF
22:
INPUT
470 pF
ALERT
5 k:
R
P
R
P
Regulated Supply
V
DD
Controller
SCL
SDA
INTERRUPT
I
2
C BUS ...
ADC101C021, ADC101C027
SNAS446D –FEBRUARY 2008–REVISED FEBRUARY 2013 www.ti.com
Figure 33. Typical Application Circuit
BUFFERED INPUT
A buffered input application circuit is shown in Figure 34. The analog input is buffered by a National
Semiconductor LMP7731. The non-inverting amplifier configuration provides a buffered gain stage for a single
ended source. This application circuit is good for single-ended sensor interface. The input must have a DC bias
level that keeps the ADC input signal from swinging below GND or above the supply (+5V in this case).
The LM4132, with its 0.05% accuracy over temperature, is an excellent choice as a reference source for the
ADC101C021.
Figure 34. Buffered Input Circuit
INTELLIGENT BATTERY MONITOR
The ADC101C021 is easily used as an intelligent battery monitor. The simple circuit shown in Figure 35, uses
the ADC101C021, the LP2980 fixed reference, and a resistor divider to implement an intelligent battery monitor
with a window supervisory feature. The window supervisory feature is implemented 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 36). When the battery is nearing depletion, the Under Range Alert will indicate that the battery is low
(see Figure 37).
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