MCP6001/2/4
This voltage rate of change is less than the MCP6001/2/4
slew rate of 0.6 V/µs. When the input voltage swings
below the voltage across C1, D1 becomes reverse-
biased. This opens the feedback loop and rails the
amplifier. When the input voltage increases, the amplifier
recovers at its slew rate. Based on the rate of voltage
change shown in the above equation, it takes an
extended period of time to charge a 0.1 µF capacitor. The
capacitors need to be selected so that the circuit is not
limited by the amplifier slew rate. Therefore, the capaci-
tors should be less than 40 µF and a stabilizing resistor
(RISO) needs to be properly selected. (Refer to
Section 4.3 “Capacitive Loads”).
VIN
D1
+
RISO
VC1
1/2
RISO
+
VC2
MCP6002
1/2
VOUT
+
MCP6002
–
–
C1
R1
Op Amp A
MCP6001
–
C2
Op Amp B
Op Amp C
Sample
Switch
Clear
Switch
t
SAMP
Sample Signal
t
CLEAR
Clear Signal
CLK
t
DETECT
FIGURE 4-8:
Peak Detector with Clear and Sample CMOS Analog Switches.
© 2005 Microchip Technology Inc.
DS21733F-page 11
MICROCHIP [ MICROCHIP ]
