Self-Cal™ op amp with digital offset nulling
Product Features
- Self-Cal VIO = 50 µV max (TLC4502A) VIO = 100 µV
max (TLC4502)
- No external calibration components required
- Standard package, standard product
- Rail-to-Rail output voltage swing
- High output drive capability (± 50 mA )
- 300 ms typical calibration time
- 5-V single supply operation
- Operation from (0°C to 70°C) and industrial (-40°C
to 85°C)
The TLC4502 is a self-calibrating, precision dual operational
amplifier. It achieves precision by automatically nulling its
input offset voltage to 50 µV (max) during power up. During
the calibration procedure, the operational amplifier is removed
from the signal path and both inputs are tied to GND. The offset
cancellation uses a current-mode digital-to-analog converter (D/A),
whose full-scale current allows for an adjustment of approximately
±5 mV to the input offset voltage. The digital code producing
the cancellation current is stored in the successive-approximation
register (SAR). This self-calibrating procedure typically requires
300 ms to complete and is repeatable to within ±3 µV
on successive calibrations.
The TLC4502 offers significant advantages over chopper-stabilized
and precision bipolar amplifier solutions. The designer does not
have to worry about noise and frequency limitations created by
the continual chopping frequency of chopper-stabilized amplifiers.
After calibration , the calibration circuitry drops out of the
signal path, becoming transparent to the user. Also, choppers
are normally only single channel devices requiring external storage
capacitors for proper use. The Self-Cal amp uses a standard dual
op amp pinout, requires no external components and can be used
as a performance upgrade in standard designs. It is also an excellent
alternative to laser-trimmed bipolar amplifiers. Bipolar amplifiers
inherently have lower input impedance than CMOS amplifiers. This
could cause excess loading of the input signal when interfacing
with high impedance sensors. The TLC4502 offers the designer a
unique combination of DC and AC performance that makes the Self-Cal
amplifier a good choice for a wide range of amplifier applications.
The TLC4502 has rail-to-rail output swing, which makes it ideal
for interfacing with ADCs. A 5-V single supply operation makes
it a good choice when designing battery-powered applications.
The TLC4502 has ample output current to drive 100-½ loads.
The TLC4502 has ample output current to drive 100-½ loads.
With a gain bandwidth of
4.7 MHz (typ) and a slew rate of 2.5 V/µs (typ), it can also
be used in applications where good AC performance is needed.
This device is available in standard 8-pin SOIC.
