Datasheet

LM5035
CS
LO
AGND
R1
HO
Q1
Q2
Current
Sense
Power
Transformer
R
F
C
F
VIN
V
PWR
LM5035
CS
LO
AGND
Power
Transformer
HO
Q2
Q1
R1
R
F
C
F
V
PWR
VIN
Current
Sense
LM5035
9V
V
PWR
8.3V - 15V
(from aux winding)
VIN VCC
LM5035
SNVS428G –JANUARY 2006–REVISED MARCH 2013 www.ti.com
CURRENT SENSE
The CS pin needs to receive an input signal representative of the transformer’s primary current, either from a
current sense transformer or from a resistor in series with the source of the LO switch, as shown in Figure 18
and Figure 19. In both cases, the sensed current creates a ramping voltage across R1, and the R
F
/C
F
filter
suppresses noise and transients. R1, R
F
and C
F
should be located as close to the LM5035 as possible, and the
ground connection from the current sense transformer, or R1, should be a dedicated track to the AGND pin. The
current sense components must provide greater than 0.25V at the CS pin when an over-current condition exists.
Figure 17. Start-Up Regulator for V
PWR
>100V
Figure 18. Current Sense Using Current Sense Transformer
Figure 19. Current Sense Using Current Sense Resistor (R1)
18 Submit Documentation Feedback Copyright © 2006–2013, Texas Instruments Incorporated
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