AD5235 Analog Devices, AD5235 Datasheet - Page 8

• Manufacturer Part Number: AD5235
• Description: 8-Bit Dual Nonvolatile Memory Digital Potentiometer
• Manufacturer: Analog Devices

Nonvolatile Memory Digital Potentiometers
R
Similarly, eqn. 3 becomes:
R
For example, when V
the following output resistance values will be set for the following
RDAC latch codes (applies to R
Dx
(DEC)
1023
512
1
0
A ±1% typical distribution of R
within the same package. On the other hand, device to device
matching is process lot dependent such that a maximum of ±30%
variation is possible. The change in R
ppm/°C temperature coefficient.
PROGRAMMING THE POTENTIOMETER DIVIDER
Voltage Output Operation
The digital potentiometer easily generates an output voltage
proportional to the input voltage applied to a given terminal. For
example connecting A–terminal to +5V and B–terminal to ground
produces an output voltage at the wiper which can be any value
starting at zero volts and up to 1 LSB less than +5V. Each LSB of
voltage is equal to the voltage applied across terminal AB divided
by the 2
equation defining the output voltage with respect to ground for any
given input voltage applied to terminals AB is:
V
Since N=10,
V
Operation of the digital potentiometer in the divider mode results in
more accurate operation over temperature. Here the output voltage
is dependent on the ratio of the internal resistors and not the
absolute value. Therefore, the drift reduces to 15ppm/°C.
REV PrD 6 NOV, 2000
Information contained in this Product Concept data sheet describes a product in the early definition stage. There is no guarantee that the
information contained here will become a final product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara,
CA. TEL[phone]; FAX [phone]; [e-mail]
WA
WA
W
W
(Dx) = Dx/2
(Dx) = (Dx/1024) * V
(Dx) = [ (2
(Dx) = [ (1024-Dx)/1024 ] * R
N
R
( )
74
12500
25000
25050
resolution of the potentiometer divider. The general
WA
N
N
-Dx)/2
* V
Output State
Full-Scale
Mid-Scale
1 LSB
Zero-Scale
AB
A
= 0V and B–terminal is tied to the wiper W
N
+ V
] * R
AB
B
+ V
eqn. 5
AB
AB
AB
B
PRELIMINARY TECHNICAL DATA
+ R
=10K potentiometers):
from channel-to-channel occurs
AB
W
AB
+ 50
eqn. 6
with temperature has a 50
eqn. 3
eqn. 4
8
ESD PROTECTION CIRCUITS
Figure 5 shows the equivalent ESD protection circuit for digital
pins. Figure 6 shows the equivalent analog-terminal protection
circuit for the variable resistors.
Figure 5C. Equivalent SDO Output ESD Protection Circuit
Figure 5B. Equivalent Digital Output ESD Protection
Figure 5A. Equivalent Digital Input ESD Protection
Figure 6. Equivalent VR-Terminal ESD Protection
L O G IC
P IN S
A , B , W
P IN S
V
V
D D
D D
IN P U T S
G N D
O U T P U T S
P O T E N T IO M E T E R
G N D
O U T P U T S
T E R M IN A L S
V
G N D
S S
AD5235
O 1 & O 2
V
P IN S
D D
S D O
P IN