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TPS3103xxx
TPS3106xxx
TPS3110xxx
SLVS363E – AUGUST 2001 – REVISED SEPTEMBER 2007
APPLICATION INFORMATION
The TPS31xx family has a quiescent current in the 1-μA to 2-μA range. When RESET is active, triggered by the
voltage monitored at V
DD
, the quiescent current increases to about 20
μA
(see the
In some applications it is necessary to minimize the quiescent current even during the reset period. This is
especially true when the voltage of a battery is supervised and the RESET is used to shut down the system or
for an early warning. In this case the reset condition will last for a longer period of time. The current drawn from
the battery should almost be zero, especially when the battery is discharged.
For this kind of application, either the TPS3103 or TPS3106 is a good fit. To minimize current consumption,
select a version where the threshold voltage is lower than the voltage monitored at V
DD
. The TPS3106 has two
reset outputs. One output (RSTVDD) is triggered from the voltage monitored at V
DD
. The other output
(RSTSENSE) is triggered from the voltage monitored at SENSE. In the application shown in
the
TPS3106E09 is used to monitor the input voltage of two NiCd or NiMH cells. The threshold voltage (V
(TH)
= 0.86
V) was chosen as low as possible to ensure that the supply voltage is always higher than the threshold voltage
at V
DD
. The voltage of the battery is monitored using the SENSE input. The voltage divider was calculated to
assert a reset using the RSTSENSE output at 2
×
0.8 V = 1.6 V.
R1
+
R2
where:
V
TRIP
*
1
V
IT(S)
(1)
V
TRIP
is the voltage of the battery at which a reset is asserted and
V
IT(S)
is the threshold voltage at SENSE = 0.551 V.
R1 was chosen for a resistor current in the 1-μA range.
With V
TRIP
= 1.6 V:
R1
≡
1.9
×
R2
R1 = 820 kΩ, R2 = 430 kΩ
V
DD
R1
2 Cell
NiMH
R2
TPS3106E09DBV
RSTVDD
SENSE
RSTSENSE
GND
MR
R3
Reset Output
Figure 8. Battery Monitoring with 3-μA Supply Current for Device and Resistor Divider
Copyright © 2001–2007, Texas Instruments Incorporated
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