MCP4726A2T-E Datasheet, PDF (34/86 Pages) Microchip Technology – 8-/10-/12-Bit Voltage Output Digital-to-Analog Converter

MCP4706/4716/4726
3.1 Analog Output Voltage Pin (V_OUT)
V_OUT is the DAC analog output pin. The DAC output
has an output amplifier. V_OUT can swing from
approximately 0V to approximately V_DD. The full-scale
range of the DAC output is from V_SS to G * V_RL, where
G is the gain selection option (1x or 2x).
In Normal mode, the DC impedance of the output pin is
about 1Ω. In Power-Down mode, the output pin is
internally connected to a known pull-down resistor of
1 kΩ, 125 kΩ, or 640 kΩ. The power-down selection
bits settings are shown in Table 4-2.
3.2 Positive Power Supply Input (V_DD)
V_DD is the positive supply voltage input pin. The input
supply voltage is relative to V_SS.
The power supply at the V_DD pin should be as clean as
possible for a good DAC performance. It is
recommended to use an appropriate bypass capacitor
of about 0.1 µF (ceramic) to ground. An additional
10 µF capacitor (tantalum) in parallel is also
recommended to further attenuate high-frequency
noise present in application boards.
3.3 Ground (V_SS)
The V_SS pin is the device ground reference.
The user must connect the V_SS pin to a ground plane
through a low-impedance connection. If an analog
ground path is available in the application Printed
Circuit Board (PCB), it is highly recommended that the
V_SS pin be tied to the analog ground path or isolated
within an analog ground plane of the circuit board.
3.4 Serial Data Pin (SDA)
SDA is the serial data pin of the I²C interface. The SDA
pin is used to write or read the DAC registers and Con-
figuration bits. The SDA pin is an open-drain N-channel
driver. Therefore, it needs a pull-up resistor from the
V_DD line to the SDA pin. Except for Start and Stop
conditions, the data on the SDA pin must be stable
during the high period of the clock. The high or low
state of the SDA pin can only change when the clock
signal on the SCL pin is low. Refer to Section 5.0 “I²C
Serial Interface” for more details of I²C serial interface
communication.
3.5 Serial Clock Pin (SCL)
SCL is the serial clock pin of the I²C interface. The
MCP47X6 devices act only as a slave and the SCL pin
accepts only external serial clocks. The input data from
the master device is shifted into the SDA pin on the
rising edges of the SCL clock and output from the
device occurs at the falling edges of the SCL clock. The
SCL pin is an open-drain N-channel driver. Therefore,
it needs a pull-up resistor from the V_DD line to the SCL
pin. Refer to Section 5.0 “I²C Serial Interface” for
more details about I²C serial interface communication.
3.6 Voltage Reference Pin (V_REF)
This pin is used for the external voltage reference input.
The user can select V_DD voltage or the V_REF pin
voltage as the reference resistor ladder’s voltage
reference.
When the V_REF pin signal is selected, there is an option
for this voltage to be buffered or unbuffered. This is
offered in cases where the reference voltage does not
have the current capability not to drop its voltage when
connected to the internal resistor ladder circuit.
When the V_DD is selected as reference voltage, this pin
is disconnected from the internal circuit.
See Section 4.2 “DAC’s (Resistor Ladder)
Reference Voltage” and Table 4-4 for more details on
the Configuration bits.
3.7 Exposed Pad (EP)
This pad is conductively connected to the device's
substrate. This pad should be tied to the same potential
as the V_SS pin (or left unconnected). This pad could be
used to assist as a heat sink for the device when
connected to a PCB heat sink.
DS22272C-page 34
© 2011-2012 Microchip Technology Inc.