Microchip Technology MCP6V01DM-VOS User Manual
MCP6V01 Input Offset Demo Board User’s Guide
DS51801A-page 10
© 2009 Microchip Technology Inc.
2.4
OPERATING CONDITIONS
This board works most effectively at room temperature (near +25°C). Measurements
at other temperatures should be done in an oven where the air velocity is minimal.
at other temperatures should be done in an oven where the air velocity is minimal.
The power supply (V
DD
) should be between 1.8V and 5.5V.
The common mode voltage (V
CM
) needs to be between 0.3V and V
DD
– 0.3V for proper
operation of this demo board.
2.5
CALCULATING THE DUT’S INPUT OFFSET VOLTAGE
The DUT’s total input offset voltage (V
OST
) can be calculated from a measurement as
EQUATION 2-1:
2.6
CONVERTING INPUT OFFSET VOLTAGE TO OTHER PARAMETERS
2.6.1
Theory
Changing the bias voltages changes the input offset voltage. Microchip’s application
note AN1177 discusses in detail how these changes in V
note AN1177 discusses in detail how these changes in V
OS
are related to specifications
found in our data sheets. The following list summarizes the parameters that contribute
to V
to V
OST
:
• Specified Input Offset Voltage:
- V
OS
= Input offset at the specified bias point
• DC Common Mode Rejection Ratio:
- CMRR =
ΔV
CM
/
ΔV
OS
• DC Power Supply Rejection Ratio:
- PSRR = (
ΔV
DD
–
ΔV
SS
)/
ΔV
OS
• DC Open-Loop Gain:
- A
OL
=
ΔV
OUT
/
ΔV
OS
• Input Offset Drift over Temperature:
-
ΔV
OS
/
ΔT
A
V
OST
V
M
V
DD
2
⁄
–
(
) 1 G
DA
G
N
(
)
⁄
(
)
⋅
=
Where:
1/(G
DA
G
N
)
≈ 10.0 µV/V
Note:
The data sheet Input Offset Voltage (V
OS
) specification applies to one bias
point and temperature only. The total input offset voltage (V
OST
) includes
V
OS
and other changes in input offset as bias voltages and temperature
change.