lm25066apsqx National Semiconductor Corporation, lm25066apsqx Datasheet - Page 24

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

www.national.com
The four resistor values are calculated as follows: - Choose
the upper and lower UVLO thresholds (V
- Choose the upper and lower OVLO threshold (V
(V
As an example, assume the application requires the following
thresholds: V
14V. Therefore V
sistor values are:
R1 = 43.5 kΩ, R2 = 8.64 kΩ
R3 = 65.2 kΩ, R4 = 5.27 kΩ
OVL
).
UVH
= 8V, V
UV(HYS)
UVL
= 1V, and V
= 7V, V
OVH
OV(HYS)
FIGURE 11. Programming the Four Thresholds
= 15.5V, and V
UVH
) and (V
= 1.5V. The re-
FIGURE 12. UVLO = POR
OVH
UVL
) and
OVL
).
(22)
(23)
(24)
(25)
=
24
Where the R1-R4 resistor values are known, the threshold
voltages and hysteresis are calculated from the following:
Option C: The minimum UVLO level is obtained by connect-
ing the UVLO/EN pin to VIN as shown in
switched on when the VIN voltage reaches the POR threshold
(
values are calculated using the procedure in Option B.
≊
2.6V). The OVLO thresholds are set using R3, R4. Their
V
V
UV(HYS)
OV(HYS)
30146050
30146041
= R1 x 23 µA
= R3 x 23 µA
Figure
12. Q1 is
(26)
(27)
(28)
(29)