lm5066pmhx National Semiconductor Corporation, lm5066pmhx Datasheet - Page 22

• Manufacturer Part Number: lm5066pmhx
• Description: High Voltage System Power Management And Protection Ic With Pmbus
• Manufacturer: National Semiconductor Corporation

www.national.com
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
= 36V, V
UVL
).
OVL
UVL
must be accurately defined in
= 32V, V
OVL
) cannot be chosen in ad-
FIGURE 10. UVLO and OVLO Thresholds Set By R1-R3
OVH
OVH
UVH
).
= 60V.
), and the lower
(11)
(12)
(13)
(14)
(15)
22
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:
Option B: If all four thresholds must be accurately defined,
the configuration in
V
OV(HYS)
V
Figure 11
UV(HYS)
30115929
= (R1 + R2) x 21µA
= R1 x 20µA
can be used.
(16)
(17)
(18)
(19)
(20)
(21)