lm25066apsqx National Semiconductor Corporation, lm25066apsqx Datasheet - Page 23

• Manufacturer Part Number: lm25066apsqx
• Description: Lm25066a System Power Management And Protection Ic With Pmbus
• Manufacturer: National Semiconductor Corporation

The procedure to calculate the resistor values is as follows:
- Choose the upper UVLO threshold (V
UVLO threshold (V
- Choose the upper OVLO threshold (V
- The lower OVLO threshold (V
vance in this case, but is determined after the values for R1-
R3 are determined. If V
addition to the other three thresholds, see Option B below.
The resistors are calculated as follows:
The lower OVLO threshold is calculated from:
As an example, assume the application requires the following
thresholds: V
UVH
= 8V, V
UVL
).
UVL
OVL
= 7V, V
must be accurately defined in
OVL
) cannot be chosen in ad-
FIGURE 10. UVLO and OVLO Thresholds Set By R1-R3
OVH
OVH
= 15V.
UVH
).
), and the lower
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23
The lower OVLO threshold calculates to 12.03V, and the OV-
LO hysteresis is 2.97V. Note that the OVLO hysteresis is
always slightly greater than the UVLO hysteresis in this con-
figuration. When the R1-R3 resistor values are known, the
threshold voltages and hysteresis are calculated from the fol-
lowing:
Option B: If all four thresholds must be accurately defined,
the configuration in
V
OV(HYS)
V
Figure 11
UV(HYS)
30146029
= (R1 + R2) x 23µA
= R1 x 23µA
can be used.
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