lm5035asqx National Semiconductor Corporation, lm5035asqx Datasheet - Page 20

• Manufacturer Part Number: lm5035asqx
• Description: Pwm Controller With Integrated Half-bridge And Syncfet Drivers
• Manufacturer: National Semiconductor Corporation

www.national.com
The impedance seen looking into the resistor divider from the
UVLO and OVP pins determines the hysteresis level. UVLO
and OVP enable and disable thresholds are calculated using
The typical operating ranges of undervoltage and overvoltage
thresholds are calculated from the above equations. For ex-
ample, for resistor values R1 = 86.6kΩ, R2 = 2.10kΩ and R3
= 1.40kΩ the computed thresholds are:
Outputs disabled due to VIN falling below UVLO threshold
Outputs enabled due to VIN rising above UVLO threshold
Outputs disabled due to VIN rising above OVP threshold
Outputs enabled due to VIN falling below OVP threshold
FIGURE 11. Basic Over-Voltage Protection
TABLE 1. UVO/OVP Divider Formulas
FIGURE 12. UVLO/OVP Divider
20
UVLO
OVP
the equations in the table below for the three-resistor divider
illustrated in Figure 12.
UVLO turn-off = 32.2V
UVLO turn-on = 34.2V
OVP turn-on = 78.4V
OVP turn-off = 80.5V
on
on
= OVP
= UVLO
off
- [23 µA x (R1 + R2)]
off
+ (23 µA x R
30034130
30034131
1
)