MCP4726 datasheet(64/86 Pages) MICROCHIP

64 / 86 page

MCP4706/4716/4726

DS22272A-page 64

8.2

Power Supply Considerations

The power source should be as clean as possible. The

power supply to the device is also used for the DAC

voltage reference internally if the internal VDD is

selected as the resistor ladders reference voltage

(VREF1:VREF0 = 00 or 01).

Any noise induced on the VDD line can affect the DAC

performance. Typical applications will require a bypass

capacitor in order to filter out high frequency noise on

the VDD line. The noise can be induced onto the power

supply’s traces or as a result of changes on the DAC

output. The bypass capacitor helps to minimize the

effect of these noise sources on signal integrity.

Figure 8-2 shows an example of using two bypass

capacitors (a 10 µF tantalum capacitor and a 0.1 µF

ceramic capacitor) in parallel on the VDD line. These

capacitors should be placed as close to the VDD pin as

possible (within 4 mm). If the application circuit has

separate digital and analog power supplies, the VDD

and VSS pins of the device should reside on the analog

plane.

FIGURE 8-2:

Example MCP47X6 Circuit

with SOT-23 package.

Analog

VDD

SCL

SDA

VSS

VOUT

R1 R2

To MCU

R1 and R2 are I2C pull-up resistors:

R1 and R2:

Ω - 10 kΩ for f

SCL

= 100 kHz to 400 kHz

~700

Ω for f

SCL

= 3.4 MHz

C1:

0.1 µF capacitor

Ceramic

C2:

10 µF capacitor

Tantalum

C3:

~ 0.1 µF

Optional to reduce noise

in VOUT pin.

C4:

0.1 µF capacitor

Ceramic

C5:

10 µF capacitor

Tantalum

Optional

(a) Circuit when VDD is selected as reference

(Note: VDD is connected to the reference circuit internally.)

(b) Circuit when external reference is used.

Output

VREF

Analog

VDD

SCL

SDA

VSS

VOUT

R1 R2

To MCU

Optional

Output

VREF

Optional

VREF

Note: Pin assignment is opposite in DFN-6 package.

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