LM5035ASQ datasheet(22/30 Pages) NSC

Part #	LM5035ASQ

Description	PWM Controller with Integrated Half-Bridge and SyncFET PWM Controller with Integrated Half-Bridge and SyncFET

PDF	30 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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22 / 30 page

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FIGURE 11. Basic Over-Voltage Protection

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FIGURE 12. UVLO/OVP Divider

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 equations in the table below for the three-resistor divider

illustrated in Figure 12.

TABLE 1. UVO/OVP Divider Formulas

Outputs disabled due to VIN falling below UVLO threshold

Outputs enabled due to VIN rising above UVLO threshold

UVLO

on = UVLOoff + (23 µA x R1)

Outputs disabled due to VIN rising above OVP threshold

Outputs enabled due to VIN falling below OVP threshold

OVP

on = OVPoff - [23 µA x (R1 + R2)]

The typical operating ranges of undervoltage and overvoltage

thresholds are calculated from the above equations. For ex-

ample, for resistor values R1 = 86.6k

Ω, R2 = 2.10kΩ and R3

= 1.40k

Ω the computed thresholds are:

UVLO turn-off = 32.2V

UVLO turn-on = 34.2V

OVP turn-on = 78.4V

OVP turn-off = 80.5V

LM5035ASQ Datasheet(PDF) 22 Page - National Semiconductor (TI)