MCP4431 Microchip Technology Inc., MCP4431 Datasheet - Page 85

• Manufacturer Part Number: MCP4431
• Description: 7/8-bit Volatile Quad Digital Pot With I 2c Interface
• Manufacturer: Microchip Technology Inc.

APPENDIX B:
Some designers may want to understand the device
operational characteristics outside of the specified
operating conditions of the device.
Applications where the knowledge of the resistor
network characteristics could be useful include battery
powered devices and applications that experience
brown-out conditions.
In battery applications, the application voltage decays
over time until new batteries are installed. As the
voltage decays, the system will continue to operate. At
some voltage level, the application will be below its
specified operating voltage range. This is dependent
on the individual components used in the design. It is
still useful to understand the device characteristics to
expect when this low-voltage range is encountered.
Unlike a microcontroller, which can use an external
supervisor device to force the controller into the Reset
state, a digital potentiometer’s resistance characteristic
is not specified. But understanding the operational
characteristics can be important in the design of the
applications circuit for this low-voltage condition.
Other
understanding the low-voltage characteristics of the
resistor network could be important is for system brown
out conditions.
For the MCP443X/5X devices, the analog operation is
specified at a minimum of 2.7V. Device testing has Ter-
minal A connected to the device V
potentiometer configuration only) and Terminal B
connected to V
 2010 Microchip Technology Inc.
application
SS
.
CHARACTERIZATION
DATA ANALYSIS
system
scenarios
DD
(for the
where
B.1
This
semiconductor characteristics at lower voltages. This is
important
characterization graphs of the MCP443X/5X devices
can be better understood.
For this discussion, we will use the 5 k device data.
This data was chosen since the variations of wiper
resistance have much greater implications for devices
with smaller R
Figure B-1
average R
the R
Non-linear behavior occurs at approximately wiper
code 160. This is better shown in
R
change is due to the change in the wiper resistance.
FIGURE B-1:
from Average R
and Temperature (V
FIGURE B-2:
Temperature (V
BW
7000
6000
5000
4000
3000
2000
1000
resistance changes from a linear slope. This
-1.00%
-2.00%
-3.00%
-4.00%
-5.00%
-6.00%
-7.00%
BW
2.00%
1.00%
0.00%
appendix
0
Low-Voltage Operation
0
BW
resistance versus the wiper code graph.
0
shows the worst case R
so
as a percentage, while
32
AB
32
that
resistances.
BW
DD
gives
64
64
MCP443X/5X
= 1.8V, I
(R
DD
1.8V Worst Case R
R
the
BW0
96
BW
96
Wiper Code
= 1.8V, I
an
Wiper Code
-R
vs. Wiper Code And
128
1.8V
128
W
BW3
overview
Figure
= 190
160
160
W
) vs. Wiper Code
resistor
BW
DS22267A-page 85
Figure B-2
= 190
192
192
B-2, where the
µ
error from the
A).
of
-40C
+25C
+85C
+125C
224
224
BW
-40C
+25C
+85C
+125C
µ
A).
network
CMOS
shows
Error
256
256