Datasheet

VIN
UVLO/EN
OVLO
GND
R1
R3
R4
2.48V
2.46V
TIMER AND
GATE
LOGIC CONTROL
LM5066
V
IN
R2
21 PA
20 PA
LM5066
SNVS655G –JUNE 2011–REVISED FEBRUARY 2013 www.ti.com
The lower OVLO threshold calculates to 55.6V, and the OVLO hysteresis is 4.4V. 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:
(18)
(19)
V
UV(HYS)
= R1 x 20µA (20)
(21)
(22)
V
OV(HYS)
= (R1 + R2) x 21µA (23)
Option B: If all four thresholds must be accurately defined, the configuration in Figure 11 can be used.
Figure 11. Programming the Four Thresholds
The four resistor values are calculated as follows: - Choose the upper and lower UVLO thresholds (V
UVH
) and
(V
UVL
).
(24)
(25)
- Choose the upper and lower OVLO threshold (V
OVH
) and (V
OVL
).
(26)
(27)
As an example, assume the application requires the following thresholds: V
UVH
= 36V, V
UVL
= 32V, V
OVH
= 60V,
and V
OVL
= 56V. Therefore V
UV(HYS)
= 4V, and V
OV(HYS)
= 4V. The resistor values are:
R1 = 200 kΩ, R2 = 16.8 kΩ
R3 = 190 kΩ, R4 = 8.1 kΩ
When the R1-R4 resistor values are known, the threshold voltages and hysteresis are calculated from the
following:
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