Datasheet

 2003-2012 Microchip Technology Inc. DS21117B-page 15
MCP6S21/2/6/8
3.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1: PIN FUNCTION TABLE
3.1 Analog Output
The output pin (V
OUT
) is a low-impedance voltage
source. The selected gain (G), selected input (CH0-
CH7) and voltage at V
REF
determine its value.
3.2 Analog Inputs (CH0 thru CH7)
The inputs CH0 through CH7 connect to the signal
sources. They are high-impedance CMOS inputs with
low bias currents. The internal MUX selects which one
is amplified to the output.
3.3 External Reference Voltage (V
REF
)
The V
REF
pin should be at a voltage between V
SS
and
V
DD
(the MCP6S22 has V
REF
tied internally to V
SS
).
The voltage at this pin shifts the output voltage.
3.4 Power Supply (V
SS
and V
DD
)
The positive power supply pin (V
DD
) is 2.5V to 5.5V
higher than the negative power supply pin (V
SS
). For
normal operation, the other pins are between V
SS
and
V
DD
.
Typically, these parts are used in a single (positive)
supply configuration. In this case, V
SS
is connected to
ground and V
DD
is connected to the supply. V
DD
will
need a local bypass capacitor (0.1 µF) at the V
DD
pin.
It can share a bulk capacitor with nearby analog parts
(typically 2.2 µF to 10 µF within 4 inches (100 mm) of
the V
DD
pin.
3.5 Digital Inputs
The SPI interface inputs are: Chip Select (CS), Serial
Input (SI) and Serial Clock (SCK). These are Schmitt-
triggered, CMOS logic inputs.
3.6 Digital Output
The MCP6S26 and MCP6S28 devices have a SPI
interface serial output (SO) pin. This is a CMOS push-
pull output and does not ever go High-Z. Once the
device is deselected (CS
goes high), SO is forced low.
This feature supports daisy chaining, as explained in
Section 5.3, “Daisy Chain Configuration”.
MCP6S21 MCP6S22 MCP6S26 MCP6S28 Symbol Description
1111V
OUT
Analog Output
2222CH0Analog Input
— 3 3 3 CH1 Analog Input
— — 4 4 CH2 Analog Input
— — 5 5 CH3 Analog Input
— — 6 6 CH4 Analog Input
— — 7 7 CH5 Analog Input
— — — 8 CH6 Analog Input
— — — 9 CH7 Analog Input
3—810V
REF
External Reference Pin
44911V
SS
Negative Power Supply
5 5 10 12 CS SPI Chip Select
6 6 11 13 SI SPI Serial Data Input
— — 12 14 SO SPI Serial Data Output
7 7 13 15 SCK SPI Clock Input
8 8 14 16 V
DD
Positive Power Supply