LM5035 datasheet(20/28 Pages) NSC

Part #	LM5035

Description	PWM Controller with Integrated Half-Bridge and SyncFET Drivers

PDF	28 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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20 / 28 page

Applications Information (Continued)

the power converter as shown in Figure 10. When the UVLO

pin voltage falls below the 1.25V threshold, an internal 23 µA

current sink is enabled to lower the voltage at the UVLO pin,

thus providing threshold hysteresis. Resistance values for

R1 and R2 can be determined from the following equations.

where V

PWR is the desired turn-on voltage and VHYS is the

desired UVLO hysteresis at V

PWR.

For example, if the LM5035 is to be enabled when V

PWR

reaches 34V, and disabled when VPWR is decreased to

32V, R1 should be 87k

Ω, and R2 should be 3.54kΩ. The

voltage at the UVLO pin should not exceed 7V at any time.

Be sure to check both the power and voltage rating (0603

resistors can be rated as low as 50V) for the selected R1

resistor.

20177529

FIGURE 10. Basic UVLO Configuration

20177530

FIGURE 11. Basic Over-Voltage Protection

LM5035 Datasheet(PDF) 20 Page - National Semiconductor (TI)