ICL7621 View Datasheet(PDF) - Intersil
Part Name
Description
Manufacturer
ICL7621 Datasheet PDF : 9 Pages
| |||
ICL7621, ICL7641, ICL7642
Choosing the Proper IQ
Each device in the ICL76XX family has a similar IQ setup
scheme, which allows the amplifier to be set to nominal
quiescent currents of 10µA, 100µA or 1mA. These current
settings change only very slightly over the entire supply
voltage range. The ICL7611/12 have an external IQ control
terminal, permitting user selection of each amplifiers’
quiescent current. The ICL7621 and ICL7641/7642 have
fixed IQ settings:
ICL7621 (Dual) - IQ = 100µA
ICL7641 (Quad) - IQ = 1mA
ICL7642 (Quad) - IQ = 10µA
NOTE: The output current available is a function of the
quiescent current setting. For maximum peak-to-peak output
voltage swings into low impedance loads, IQ of 1mA should
be selected.
Output Stage and Load Driving Considerations
Each amplifiers’ quiescent current flows primarily in the
output stage. This is approximately 70% of the IQ settings.
This allows output swings to almost the supply rails for
output loads of 1MΩ, 100kΩ, and 10kΩ, using the output
stage in a highly linear class A mode. In this mode,
crossover distortion is avoided and the voltage gain is
maximized. However, the output stage can also be operated
in Class AB for higher output currents. (See graphs under
VIN
+
ICL76XX
VOUT
-
RL ≥ 10kΩ
Typical Operating Characteristics). During the transition from
Class A to Class B operation, the output transfer
characteristic is nonlinear and the voltage gain decreases.
Frequency Compensation
The ICL76XX are internally compensated, and are stable
for closed loop gains as low as unity with capacitive loads
up to 100pF.
Operation At VSUPPLY = ±1V
Operation at VSUPPLY = ±1V is guaranteed for the
ICL7642C only.
Output swings to within a few millivolts of the supply rails are
achievable for RL ≥ 1MΩ. Guaranteed input CMVR is ±0.6V
minimum and typically +0.9V to -0.7V at VSUPPLY = ±1V. For
applications where greater common mode range is
desirable, refer to the ICL7612 data sheet.
Typical Applications
The user is cautioned that, due to extremely high input
impedances, care must be exercised in layout, construction,
board cleanliness, and supply filtering to avoid hum and
noise pickup.
Note that in no case is IQ shown. The value of IQ must be
chosen by the designer with regard to frequency response
and power dissipation.
+5
VIN
100kΩ
+5
-
ICL76XX
+
VOUT
TO CMOS OR
LPTTL LOGIC
FIGURE 1. SIMPLE FOLLOWER
1MΩ
FIGURE 2. LEVEL DETECTOR
1µF+
-
ICL76XX
λ
+
VOUT
NOTE: Low leakage currents allow integration times up to
several hours.
FIGURE 3. PHOTOCURRENT INTEGRATOR
5
-
1/2
ICL7621
+
1MΩ
1MΩ
-
1/2
ICL7621
+
1MΩ
V-
V+
DUTY CYCLE
680kΩ
WAVEFORM GENERATOR
NOTE: Since the output range swings exactly from rail to rail, fre-
quency and duty cycle are virtually independent of power supply
variations.
FIGURE 4. TRIANGLE/SQUARE WAVE GENERATOR
|
|
Share Link: 