LM5035 datasheet(21/28 Pages) NSC

部件名	LM5035

功能描述	PWM Controller with Integrated Half-Bridge and SyncFET Drivers

PDF	28 Pages

Scroll/Zoom	100%

制造商	NSC [National Semiconductor (TI)]

网页	http://www.national.com

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21 / 28 page

Applications Information (Continued)

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 calcu-

lated 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 + (23µA x R1)

Outputs disabled due to VIN rising above OVP threshold

Outputs enabled due to VIN falling below OVP threshold

OVP

on = OVPoff - [23µA x (R1 + R2)]

The typical operating ranges of undervoltage and overvolt-

age thresholds are calculated from the above equations. For

example, 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

20177531

FIGURE 12. UVLO/OVP Divider

LM5035 数据表(PDF) 21 Page - National Semiconductor (TI)