MCP4901-E/MS Microchip Technology, MCP4901-E/MS Datasheet - Page 30
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MCP4901-E/MS
Manufacturer Part Number
MCP4901-E/MS
Description
DAC 8BIT SGL W/SPI 8MSOP
Manufacturer
Microchip Technology
Datasheet
1.MCP4921T-EMS.pdf
(50 pages)
Specifications of MCP4901-E/MS
Number Of Converters
1
Settling Time
4.5µs
Package / Case
8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
Number Of Bits
8
Data Interface
Serial, SPI™
Voltage Supply Source
Single Supply
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Number Of Dac Outputs
1
Resolution
8 bit
Interface Type
SPI
Supply Voltage (max)
6.5 V
Supply Voltage (min)
2.7 V
Maximum Operating Temperature
+ 125 C
Mounting Style
SMD/SMT
Minimum Operating Temperature
- 55 C
Supply Current
175 uA
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power Dissipation (max)
-
Lead Free Status / Rohs Status
Lead free / RoHS Compliant
Available stocks
Company
Part Number
Manufacturer
Quantity
Price
Part Number:
MCP4901-E/MS
Manufacturer:
MICROCHIP/微芯
Quantity:
20 000
MCP4901/4911/4921
6.5
Bipolar operation is achievable using the MCP4901/
4911/4921 family devices by using an external
operational amplifier (op amp). This configuration is
desirable due to the wide variety and availability of op
amps. This allows a general purpose DAC, with its cost
and availability advantages, to meet almost any
desired output voltage range, power and noise
performance.
EXAMPLE 6-3:
6.5.1
An output step magnitude of 1 mV with an output range
of ±2.05V is desired for a particular application.
The following steps show the details:
1.
2.
3.
DS22248A-page 30
If R
(a) Single Output DAC:
(b) Dual Output DAC:
Calculate the range: +2.05V – (-2.05V) = 4.1V.
Calculate the resolution needed:
4.1V/1 mV = 4100
Since 2
The amplifier gain (R
must be equal to the desired minimum output to
achieve bipolar operation. Since any gain can
be realized by choosing resistor values
(R
mined first. If a V
the gain by setting the DAC to 0, knowing that
the output needs to be -2.05V. The equation can
be simplified to:
1
V
V
V
= 20 k and R
OUT
IN+
O
1
–
-------- -
+ R
R
Bipolar Operation
=
R
1
2
=
=
V
DESIGN EXAMPLE: DESIGN A BIPOLAR
DAC USING EXAMPLE 6-3 WITH 12-BIT
MCP4912 OR MCP4922
12
2
=
IN+
), the V
V
------------------- -
R
V
= 4096, 12-bit resolution is desired.
OUT
3
–
------------ -
V
REF
2.05
+
REF
1
R
R
+
4
4
R
----- -
R
REF
2
G
=
REF
2
1
= 10 k, the gain will be 0.5
DIGITALLY-CONTROLLED BIPOLAR VOLTAGE SOURCE.
MCP4902
MCP4912
MCP4922
–
------------ -
MCP4911
MCP4921
MCP4901
D
------
2
–
2.05
4.1
source needs to be deter-
N
n
2
V
of 4.1V is used, solve for
/R
DD
1
), multiplied by V
R
----- -
R
2
1
R
----- -
R
2
1
=
1
-- -
2
SPI
V
REF
3
REF
,
V
DD
D
G = Gain selection (1x or 2x)
N = DAC Bit Resolution
DAC
n
= Digital value of DAC (0 – 255) for MCP4901/MCP4902
= Digital value of DAC (0 – 1023) for MCP4911/MCP4912
= Digital value of DAC (0 – 4095) for MCP4921/MCP4922
Example 6-3
configuration. R
while R
offset. Note that R4 can be tied to V
if a higher offset is desired. Note that a pull-up to V
could be used, instead of R
desired.
4.
V
If R
OUT
Next, solve for R
4096, knowing that the output needs to be
+2.05V.
4
= 20 k, then R
3
and R
R
---------------------- -
R
3
R
3
illustrates a simple bipolar voltage source
R
4
+
V
4
4
1
R
REF
and R
4
shift the DAC's output to a selected
=
3
3
R
and R
2.05V
-----------------------------------------
2
= 10 k
2010 Microchip Technology Inc.
1
allow the gain to be selected,
0.1 µF
V
1.5V
IN
4
+
+
4
by setting the DAC to
0.5V
REF
, if a higher offset is
V
V
CC
CC
REF
REF
+
–
instead of V
=
2
-- -
3
V
O
REF
SS