LTC1197 View Datasheet(PDF) - Linear Technology
Part Name
Description
MFG CO.
'LTC1197' PDF : 28 Pages View PDF
LTC1197/LTC1197L
LTC1199/LTC1199L
TYPICAL APPLICATIO S
Battery Current Monitor
The LTC1197L/LTC1199L are ideal for 3V systems. Fig-
ure 14 shows a 2.7V to 4V battery current monitor that
draws only 45µA at 3V from the battery it monitors,
sampling at a 1Hz rate. To minimize supply current, the
microprocessor uses the LTC1152 SHDN pin to turn on
the op amp prior to making a measurement and then turn
it off after the measurement has been made. The battery
current is sensed with the 0.005Ω resistor and amplified
by the LTC1152. The LTC1197L digitizes the amplifier
output and sends it to the microprocessor in serial
format. After each sample the LTC1197L automatically
powers down. The LT1004 provides the full-scale refer-
ence for the ADC. The circuit’s 45µA supply current is
dominated by the reference and the op amp. The circuit
can be located near the battery and data transmitted
serially to the microprocessor.
2.7V
TO 4V
L
O
2k
A
D
0.005Ω
2A FULL
SCALE
500pF
240k
–
SHDN
LTC1152
+
100Ω
1µF
+
1µF
LTC1197L
1
CS
2
+ IN
3
– IN
4
GND
8
VCC
7
CLK
6
DOUT
5
VREF
0.1µF
56k TO µP
LT1004-1.2
Figure 14. This 0A to 2A Battery Current Monitor Draws Only 45µA from a 3V Battery
26
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