Datasheet

AD5260/AD5262
Rev. A | Page 22 of 24
d
ts can be programmed to the same setting
simultaneously.
ate state occurs that may not be acceptable for certain applications.
As a result, different devices can also be used in daisy-chaine
mode so that par
In voltage divider mode, a much lower resistance can be achieved
by paralleling a discrete resistor as shown in Figure 69. The
equivalent resistance becomes
WeqWB
RR2R1
D
R += )//(
256
_
(16)
+5V
OP1177
V
O
–5V
R2A
2.1kΩ
D1
D2
R2B
10kΩ
VN
R1
1kΩ
AB
W
R1 = R1' = R2B = AD5262
D1 = D2 = 1N4148
AD5262
C'
2.2nF
R'
10kΩ
AB
W
VP
C
2.2nF
FREQUENC
Y
ADJUSTMENT
R
10kΩ
A
B
W
U1
AMPLITUDE
W
eqWA
RR2R1
D
R +
⎟
⎠
⎞
⎜
⎝
⎛
−= )//(
256
1
_
(17)
W
A
B
R2
R1
R2 << R1
02695-069
Figure 69. Lowering the Nominal Resistance
ADJUSTMENT
02695-
067
cillator with Amplitude Control
le
o program
both channels coherently with the same settings.
Figure 68 and Figure 69 show that the digital potentiometers
change steps linearly. However, log taper adjustment is usually
preferred in applications like audio control. Figure 70 shows
another method of resistance scaling. In this circuit, the smaller
R2 is with respect to R
AB
, the more the pseudo-log taper
characteristic behaves.
Figure 67. Programmable Os
RESISTANCE SCALING
The AD5260/AD5262 offer 20 kΩ, 50 kΩ, and 200 kΩ nominal
resistance. For users who need lower resistance and still main-
tain the numbers of step adjustment, they can place multip
devices in parallel. For example, Figure 68 shows a simple
scheme of paralleling both channels of the AD5262. To adjust
half of the resistance linearly per step, users need t
V
O
A
B
R1
R2
V
i
W
02695-070
W1
A1
B1
W2
A2
B2
V
LD
DD
02695-
Figure 70. Resistor Scaling with Log Adjustment Characteristics
068
68. Reduce Resistance by Half with Linear Adjustment Characteristics Figure