Datasheet

V
UVH
= 2.5V + [R1 x (22 PA +
(R2 + R3)
2.5V
)]
V
UVL
=
2.5V x (R1 + R2 + R3)
R2 + R3
V
OVH
=
2.5V x (R1 + R2 + R3)
R3
V
OVL
= [(R1 + R2) x (2.5V) - 22 PA)] + 2.5V
R3
V
OV(HYS)
= (R1 + R2) x 22 PA
V
UV(HYS)
= R1 x 22 PA
R1 =
36V ± 32V
22 PA
=
4V
22 PA
= 182 k:
R3 =
2.5V x 182 k: x 32V
60V x (32V - 2.5V)
= 8.23 k:
R2 =
2.5V x 182 k:
(32V - 2.5V)
- 8.23 k: = 7.19 k:
LM5067
www.ti.com SNVS532C –OCTOBER 2007–REVISED MARCH 2013
As an example, assume the application requires the following thresholds: V
UVH
= -36V, V
UVL
= -32V, V
OVH
= -
60V.
(12)
The lower OVLO threshold calculates to -55.8V, and the OVLO hysteresis is 4.2V. Note that the OVLO
hysteresis is always slightly greater than the UVLO hysteresis in this configuration.
When the R1-R3 resistor values are known, the threshold voltages and hysteresis are calculated from the
following:
(13)
NOTE
Ensure the voltages at the UVLO and OVLO pins do not exceed the Absolute Maximum
ratings for those pins when the system voltage is at maximum.
Option B: If all four thresholds must be accurately defined, the configuration in Figure 15 can be used.
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