Datasheet
( )
ENFALLING
STOP ENFALLING P h
R1 V
R2 =
V V R1 I I
´
- + +
æ ö
-
ç ÷
è ø
æ ö
- +
ç ÷
è ø
ENFALLING
START STOP
ENRISING
ENFALLING
P h
ENRISING
V
V V
V
R1 =
V
I 1 I
V
0.7 mA
EN
i
1
i
hys
VIN
+
-
TPS54519
R1
R2
2.9 mA
VSENSE
V
O
+
-
TPS54519
R1
R2
0.6 V
TPS54519
SLVSAT3A –SEPTEMBER 2011–REVISED DECEMBER 2013
www.ti.com
Figure 16. Voltage Divider Circuit
ENABLE AND ADJUSTING UNDER-VOLTAGE LOCKOUT
The TPS54519 is disabled when the VIN pin voltage falls below 2.6 V. If an application requires a higher under-
voltage lockout (UVLO), use the EN pin as shown in Figure 17 to adjust the input voltage UVLO by using two
external resistors. It is recommended to use the enable resistors to set the UVLO falling threshold (V
STOP
) above
2.7 V. The rising threshold (V
START
) should be set to provide enough hysteresis to allow for any input supply
variations. The EN pin has an internal pull-up current source that provides the default condition of the TPS54519
operating when the EN pin floats. Once the EN pin voltage exceeds 1.25 V, an additional 2.9 μA of hysteresis is
added. When the EN pin is pulled below 1.18 V, the 2.9 μA is removed. This additional current facilitates input
voltage hysteresis.
Figure 17. Adjustable Under Voltage Lock Out
(2)
(3)
spacer
where:
I
h
= 2.9 µA
I
P
= 0.7 µA
V
ENRISING
= 1.25 V
V
ENFALLING
= 1.18 V
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