MCP4351T-503E/ML Microchip Technology, MCP4351T-503E/ML Datasheet - Page 83

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MCP4351T-503E/ML

Manufacturer Part Number
MCP4351T-503E/ML
Description
IC DGTL POT QUAD 50K 20QFN
Manufacturer
Microchip Technology
Datasheet

Specifications of MCP4351T-503E/ML

Taps
257
Resistance (ohms)
50K
Number Of Circuits
4
Temperature Coefficient
150 ppm/°C Typical
Memory Type
Volatile
Interface
SPI Serial
Voltage - Supply
1.8 V ~ 5.5 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
20-VQFN Exposed Pad, 20-HVQFN, 20-SQFN, 20-DHVQFN
Resistance In Ohms
50K
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
B.2
The low-voltage nonlinear characteristics can be
minimized by application design. The section will show
two application circuits that can be used to control a
programmable reference voltage (V
Minimizing the low-voltage nonlinear characteristics is
done by keeping the voltages on the wiper switch
nodes at a voltage where either the NMOS or PMOS
transistor is turned on.
An example of this is if we are using a digital potentiom-
eter for a voltage reference (V
want V
In example implementation #1
window the digital potentiometer using resistors R1 and
R2. When the wiper code is at full scale the V
voltage will be  0.6 * V
at zero scale the V
Remember that the digital potentiometers R
must be included.
age can be selected to be between 0.455 * V
0.727 * V
respect to the voltages on the resistor network node, at
1.8V the V
while the V
These voltages cause the wiper resistance to be in the
nonlinear region (see
mode, the variation of the wiper resistance is typically
not an issue, as shown by the INL/DNL graph
(Figure
In example implementation #2
the digital potentiometer in Rheostat mode. The resis-
tor ladder uses resistors R1 and R2 with R
bottom of the ladder. When the wiper code is at full
scale, the V
the wiper code is at full scale the V
 0.5 * V
R
the V
V
range. With respect to the voltages on the resistor net-
work node, at 1.8V the V
0.29V to 0.38V. These voltages cause the wiper
resistance to be in the linear region (see
 2010 Microchip Technology Inc.
DD
AB
variation must be included.
OUT
and 0.687 * V
OUT
2-7).
DD
Optimizing Circuit Design for Low-
Voltage Characteristics
voltage can be selected to be between 0.50 *
DD
A
B
to range from 0.5 * V
. Remember that the digital potentiometers
OUT
, which includes the desired range. With
voltage would range from 1.29V to 1.31V
voltage would range from 0.82V to 0.86V.
voltage will be  0.6 * V
Table B-1
OUT
DD
DD,
Figure
, which includes the desired
voltage will be  0.5 * V
W
and when the wiper code is
voltage would range from
shows that the V
B-12). In Potentiometer
OUT
DD
(Figure
Table B-2
). Lets say that we
OUT
to 0.6 * V
OUT
(Figure
).
voltage will be
B-16) we use
Figure
DD
AB
shows that
B-15) we
and when
BW
DD
OUT
variation
DD
.
B-12).
at the
volt-
OUT
and
DD
.
FIGURE B-15:
TABLE B-1:
R1
R2
R
V
V
V
V
Legend: FS – Full Scale, ZS – Zero Scale
A
OUT
OUT
B
AB
(@ FS) 0.714 V
(@ ZS) 0.476 V
R2
R1
MCP433X/435X
A
B
0.714 V
0.476 V
12,000
20,000
EXAMPLE #1 VOLTAGE
CALCULATIONS
8,000
V
V
Min
B
A
Example Implementation #1.
W
DD
DD
DD
DD
V
Variation
0.70 V
0.50 V
0.70 V
0.50 V
W
12,000
20,000
10,000
Typ
V
DD
DD
DD
DD
DS22242A-page 83
OUT
0.727 V
0.455 V
0.727 V
0.455 V
12,000
20,000
12,000
Max
DD
DD
DD
DD

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