Datasheet

20
9
UVLO
V
UVLO
TPS40170
+
AGND
VIN_OK
UDG-09199
I
UVLO
R1
R2
V
IN
+
1 nF
TPS40170
www.ti.com SLUS970A –MARCH 2011–REVISED NOVEMBER 2013
NOTE
To avoid potential erroneous behavior of the enable function, the ENABLE signal applied
must have a minimum slew rate of 20 V/s.
Input Undervoltage Lockout (UVLO)
The TPS40170 has both fixed and programmable input undervoltage lockout (UVLO). In order for the device to
turn ON, all of the following conditions must be met:
• The ENABLE pin voltage must be greater than V
EN
• The VBP voltage (at VBP pin) must be greater than V
VBP(on)
• The UVLO pin must be greater than V
UVLO
In order for the device to turn OFF, any one of the following conditions must be met:
• The ENABLE pin voltage must be less than V
DIS
• The VBP voltage (at VBP pin) must be less than V
VBP(off)
• The UVLO pin must be less than V
UVLO
Programming the input UVLO can be accomplished using the UVLO pin. A resistor divider from the input voltage
(VIN pin) to GND sets the UVLO level. Once the input voltage reaches a value that meets the V
UVLO
level at the
UVLO pin, then a small hysteresis current, I
UVLO
at the UVLO pin is switched in. The programmable UVLO
function is shown in Figure 17.
Figure 17. UVLO Functional Block Schematic
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