TPS3806I33-Q1 Datasheet, PDF (6/15 Pages) Texas Instruments – Dual Voltage Detector With Adjustable Hysteresis

TPS3806I33-Q1
SLVSBW8A – MARCH 2013 – REVISED MARCH 2013
LSENSE
HSENSE
V_DD
GND
FUNCTIONAL BLOCK DIAGRAM
TPS3806
_
RSTSENSE
+
R1
_
R2
+
RESET
Reference
Voltage of
1.207 V
www.ti.com
Detailed Description
Operation
The TPS3806I33-Q1 monitors battery voltage and asserts RESET when a battery becomes discharged below a
certain threshold voltage. A comparator monitors the battery voltage via an external resistor divider. When the
voltage at the LSENSE input drops below the internal reference voltage, the RSTSENSE output pulls low. The
output remains low until the battery is replaced, or recharged above a second higher trip-point, set at HSENSE.
One can monitor a second voltage at V_DD. The independent RESET output pulls low when the voltage at V_DD
drops below the fixed threshold voltage. Because the TPS3806I33-Q1 outputs are open-drain MOSFETs, most
applications may require a pullup resistor.
Programming the Threshold Voltage Levels
Calculate the low-voltage threshold at LSENSE according to Equation 1:
ǒ Ǔ V(LSENSE) + Vref
R1 ) R2 ) R3
R2 ) R3
(1)
where V_ref = 1.207 V
Calculate the high-voltage threshold at HSENSE as shown in Equation 2:
ǒ Ǔ V(HSENSE) + Vref
R1 ) R2 ) R3
R3
(2)
where V_ref = 1.207 V
To minimize battery current draw, TI recommends using 1 MΩ as the total resistor value R_(tot), with
R_(tot) = R1 + R2 + R3.
6
Submit Documentation Feedback
Product Folder Links: TPS3806I33-Q1
Copyright © 2013, Texas Instruments Incorporated