BH7600AFS, BH7601FS, BH7602FS

Technical Note

13/16

www.rohm.com

2009.03 - Rev.A

© 2009 ROHM Co., Ltd. All rights reserved.

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Operation description of each block

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BH7602FS

How to set video input level in DC_SHFT circuit

BH7602FS is build in DC_Shift block and it operate without input coupling capacitor. It is necessary to set

input voltage of VREF (7pin) terminal to VIDEO signal input level because of enough output dynamic range.

The relation of V_IN, VREF, V_OUT in this place

V_OUT=0.7+2(V_IN-VREF+0.4)

（

eq.1）

and the input possible range of VREF is

0.4≦VREF≦1.4 [V]

（

eq.2）

It shows the relation of V_IN-V_OUT at each VREF value on Fig.6.

On the other hand, the operation range of V_OUT (VIDEO OUTPUT) becomes 0.7V～3.3V (2.6Vp-p) of the

circuit composition, and needs to adjust VREF terminal voltage to be kept this range for inputted VIDEO signal.

VREF terminal voltage and V_IN input possible range are shown in Fig.5. Caution on use, after confirming

Fig.5, adjust VREF terminal voltage.

VREF [V]

V_IN input possible

range [V]

0.4

0.0～1.3

0.5

0.1～1.4

0.6

0.2～1.5

0.7

0.3～1.6

0.8

0.4～1.7

0.9

0.5～1.8

1.0

0.6～1.9

1.1

0.7～2.0

1.2

0.8～2.1

1.3

0.9～2.2

1.4

1.0～2.3

Fig. 4 DC_Shift block equivalent circuit

f

f=2(VREF-0.4)-0.7

V_IN

VREF

V_OUT

+

-

(Y, PB, PR_IN)

(Y, PB, PR_OUT)

Fig. 5 The relation of VREF terminal voltage and

input possible range

0

1

2

3

4

01

23

V_IN [V]

Vref = 0.4V

Vref = 0.9V

Vref = 1.4V

3.3V

0.7V

V_IN

=0.5V

V_IN

=1.8V

Fig. 6 The relation of V_IN-V_OUT at each VREF value

(measurement value)