LM5037MTSLASHNOPB datasheet(22/40 Pages) TI

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OUTB

AGND

VIN

Current Sense

Power Transformer

OUTA

Level

Shift

VPWR

LM5037

VIN

VCC

from aux winding

LM5037

VPWR

8.1V to 15V

LM5037

SNVS578D – NOVEMBER 2008 – REVISED MAY 2015

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Application Information (continued)

Figure 21. Start-up Regulator for VPWR >100 V

8.1.3 Current Sense

The CS pin receives an input signal representative of the transformer primary current, either from a current sense

transformer or from a resistor in series with the source of the OUTA and OUTB MOSFET switches. In both

cases, the sensed current creates a voltage ramp across R1, and the RFCF filter suppresses noise and transients

as shown in Figure 22 and Figure 23. Locate components R1, RF and CF as close to the device as possible. Use

a dedicated track from the current sense transformer (R1) to the ground connection (AGND pin). Ensure that the

current sense components provide greater than 220 mV at the CS pin when an over-current condition exists.

Figure 22. Current Sense Using Transformer

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LM5037MT/NOPB Datenblatt(PDF) 22 Page - Texas Instruments