Datasheet
HYS_UV
V
R1=
10mA
UDG0312 1
R1
200 kΩ
1 %
R2
4.99 kΩ
1 %
R3
3.92 kΩ
1 %
R9
R2
R1
R8
GND
-48V
GND
-48V
SOURCE
RTN
TPS2350
(A)
UV
OV
1
7
3
4
SOURCE
RTN
TPS2350
(A)
UV
OV
1
7
3
4
V
UV_L
R1 R2 R3
R2 R3
V
THUV
V
OV_L
R1 R2 R3
R3
V
THOV
I
HYSUV
R1
V
UV_L
R1 R2
R2
V
THUV
V
OV_L
R8 R9
R9
V
THOV
(a) (b)
=
´
=
´
–
´
=
´
=
´
+
+
+ +
+ +
TPS2350
SLUS574D –JULY 2003–REVISED OCTOBER 2013
www.ti.com
APPLICATION INFORMATION
Setting the Undervoltage and Overvoltage Thresholds
The UV and OV pins can be used to set the undervoltage (V
UV
) and overvoltage (V
OV
) thresholds of the hot swap
circuit. When the input supply is below V
UV
or above V
OV
, the GAT pin is held low, disconnecting power from the
load, and the PG output is deasserted. When input voltage is within the UV/OV window, the GAT pin drive is
enabled, assuming all other input conditions are valid for turn-on.
Threshold hysteresis is provided via two internal sources which are switched to either pin whenever the
corresponding input level exceeds the internal 1.4-V reference. The additional bias shifts the pin voltage in
proportion to the external resistance connected to it. This small voltage shift at the device pin is gained up by the
external divider to input supply levels.
A. Additional details omitted for clarity
Figure 16. Programming the Undervoltage and Overvoltage Thresholds
The UV and OV thresholds can be individually programmed with a three-resistor divider connected to the
TPS2350 as shown in the typical application diagram, and again in Figure 16a. When the desired trip voltages
and undervoltage hysteresis have been established for the protected board, the resistor values needed can be
determined from the following equations. Generally, the process is simplest by first selecting the top leg of the
divider (R1 in the diagram) needed to obtain the threshold hysteresis. This value is calculated from Equation 9.
(9)
where
• V
HYS_UV
is the undervoltage hysteresis value
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