MCP3008-I/SL Microchip Technology Inc., MCP3008-I/SL Datasheet - Page 14

• Manufacturer Part Number: MCP3008-I/SL
• Description: 10-BIT ADC, SPI, 8-CHANNEL
• Manufacturer: Microchip Technology Inc.

Specifications of MCP3008-I/SL

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

MCP3004/3008
4.2
For each device in the family, the reference input
(V
the reference input is reduced, the LSB size is reduced
accordingly.
EQUATION
The theoretical digital output code produced by the A/D
converter is a function of the analog input signal and the
reference input, as shown below.
FIGURE 4-1:
FIGURE 4-2:
Input resistance (R
0.1 LSB deviation in INL from nominal
conditions.
DS21295B-page 14
REF
Legend
VA
4
3
2
1
0
) determines the analog input voltage range. As
100
C
R
CHx
Reference Input
PIN
R
VA
SS
V
T
SS
=
=
=
=
=
CHx
Signal Source
Source Impedance
Input Channel Pad
Input Pin Capacitance
Threshold Voltage
V
f
SAMPLE
DD
Analog Input Model.
Maximum Clock Frequency vs.
Input Resistance (Ohms)
LSB Size
= V
S
REF
= 75 ksps
) to maintain less than a
= 2.7 V
1000
=
7 pF
C
V
------------ -
1024
PIN
REF
V
f
SAMPLE
DD
V
= V
DD
REF
= 200 ksps
I
C
LEAKAGE
SAMPLE
V
V
= 5 V
T
T
= 0.6V
= 0.6V
SS
R
10000
S
=
=
=
=
Leakage Current At The Pin
Due To Various Junctions
sampling switch
sampling switch resistor
sample/hold capacitance
I
±1 nA
LEAKAGE
EQUATION
When using an external voltage reference device, the
system designer should always refer to the manufac-
turer’s recommendations for circuit layout. Any instabil-
ity in the operation of the reference device will have a
direct effect on the operation of the A/D converter.
V
V
IN
REF
= analog input voltage
= reference voltage
Digital Output Code
SS
Sampling
Switch
R
S
= 1 k
2002 Microchip Technology Inc.
V
=
SS
C
= DAC capacitance
= 20 pF
1024
-------------------------- -
SAMPLE
V
REF
V
IN