VIPER37

Operation description

Doc ID 022218 Rev 1

25/35

The resistor values are such that the current sourced and sunk by the CONT pin are within

the rated capability of the internal clamp.

Figure 28.

OVP timing diagram

8.9

About the CONT pin

Referring to

Figure 29, the features below can be implemented through the CONT pin:

1.

Current limit set point

2.

Overvoltage protection on the converter output voltage

Table 11, referring to Figure 29, lists the external resistance combinations needed to

activate one or more of the CONT pin functions.

Figure 29.

CONT pin configuration

t

VAUX

t

t

t

STROBE

t

COUNTER

RESET

t

COUNTER

STATUS

t

0

CONT

(pin 4)

sampling time

OVP

FAULT

0

0

0

0 →1

1 →2

2 →0

0 →1

1 →2

2 →3

3 → 4

0

E

R

U

L

I

A

F

P

O

O

L

K

C

A

B

D

E

E

F

E

C

N

A

B

R

U

T

S

I

D

Y

R

A

R

O

P

M

E

T

N

O

I

T

A

R

E

P

O

L

A

M

R

O

N

t

t

t

t

STROBE

t

COUNTER

RESET

t

COUNTER

STATUS

t

0

(pin 4)

OVP

FAULT

0

0

0

0 →

1 →

2 →

0 →

1 →

2 →

3 →

0

E

R

U

L

I

A

F

P

O

O

L

K

C

A

B

D

E

E

F

E

C

N

A

B

R

U

T

S

I

D

Y

R

A

R

O

P

M

E

T

N

O

I

T

A

R

E

P

O

L

A

M

R

O

N

t

VOVP

T

STROBE

Current Limit Comparator

To OVP Protection

R

OVP

R

LIM

D

AUX

SOFT

START

CONT

From SenseFET

Auxiliary

winding

To PWM Logic

OVP DETECTION

LOGIC

Curr. Lim.

BLOCK

OCP