HA12167FB/HA12169FB
33
When the (variable) width of the DAC step is to be changed, the gain at step 0 or at step 63 must be
changed. The step 0 gain can be changed using R’
GP
as shown in figure 13. Also, R’
GP
can be switched
using the tape selector, as shown in figure 15. However, it is necessary to take into account that the value
of R
ADJ
, which sets the step 63 gain, is also used for the output bias. When the load resistance on pin 33 is
R
L
, the following formula gives the output bias, V
BMAX
.
V
BMAX
= 2.4
×
R
L
/ R
ADJ
Therefore, it is possible to compensate the output bias, V
BMAX
for the R
ADJ
setting by changing R
L
.
Note:
R
ADJ
should be in the range 16 k to 75 k .
28
27
26
25
24
23
22
21
16
17
18
19
20
FM
fQ
f/Q
GH
GL
GP
HM
NN
NC
NM
HN
HC
6 bit
DAC
EQ-
controler
R = R’ //
n: DAC step
GP
GP
63 R
2 n
ADJ
R’
GP
Figure 15 Switch by Tape Select
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