MCP601-I-SN N/A, MCP601-I-SN Datasheet - Page 12

• Manufacturer Part Number: MCP601-I-SN
• Description: 2.7V to 5.5V Single Supply CMOS Op Amps
• Manufacturer: N/A

MCP601/602/603/604
3.4
The MCP603 is a single amplifier with a Chip Select
option. When CS is pulled high the supply current
drops to 0.7µA (typ), which is pulled through the CS pin
to V
impedance state. By pulling CS low or letting the pin
float, the amplifier is enabled. Figure 3-6 shows the out-
put voltage and supply current response to a CS pulse.
FIGURE 3-6:
3.5
In applications where low input bias current is critical,
PC board surface leakage effects and signal coupling
from trace to trace need to be taken into consideration.
3.5.1
Surface leakage across a PC board is a consequence
of differing DC voltages between two traces combined
with high humidity, dust or contamination on the board.
For instance, the typical resistance from PC board
trace to pad is approximately 10
conditions. If an adjacent trace is biased to 5V and the
input pin of the amplifier is biased at or near zero volts,
a 5pA leakage current will appear on the amplifier’s
input node. This type of PCB leakage is five times the
room temperature input bias current (1pA, typ) of the
MCP601/602/603/604 family of amplifiers.
The simplest technique that can be used to reduce the
effects of PC board leakage is to design a ring around
sensitive pins and traces. An example of this type of
layout is shown in Figure 3-7.
DS21314D-page 12
SS
. In this state, the amplifier is put into a high
CS
Output
V
Current
GND
Current
CS
Current
The Chip Select Option of the MCP603
DD
Layout Considerations
SURFACE LEAKAGE
Supply
Timing Diagram for the CS Function of the MCP603 Amplifier
2.0nA (typ)
0.7µA (typ)
0.7µA (typ)
12
Hi-Z
Ω under low humidity
V
IL
t
ON
2nA(typ)
230µA (typ)
230µA (typ)
FIGURE 3-7:
MCP601, the A-amplifier of the MCP602 or the
MCP603 in a PC Board Layout
Guard Ring
V
t
OFF
IH
Example of Guard Ring for the
-In
 2000 Microchip Technology Inc.
Hi-Z
2.0nA (typ)
0.7µA (typ)
0.7µA (typ)
+In
V-