GENERAL DESCRIPTION
The ALD1721E is a monolithic rail-to-rail precision CMOS operational
amplifier with integrated user programmable EPAD (Electrically Programmable
Analog Device) based offset voltage adjustment. The ALD1721E
operational amplifier is a direct replacement of the ALD1701 operational
amplifier, with the added feature of user-programmable offset voltage
trimming resulting in significantly enhanced total system performance and
user flexibility. EPAD technology is an exclusive ALD design which has
been refined for analog applications where precision voltage trimming is
necessary to achieve a desired performance. It utilizes CMOS FETs as incircuit
elements for trimming of offset voltage bias characteristics with the
aid of a personal computer under software control. Once programmed, the
set parameters are stored indefinitely within the device even after powerdown.
EPAD offers the circuit designer a convenient and cost-effective
trimming solution for achieving the very highest amplifier/system performance.
The ALD1721E operational amplifier features rail-to-rail input and output
voltage ranges, tolerance to over-voltage input spikes of 300mV beyond
supply rails, capacitive loading up to 50pF, extremely low input currents of
0.01pA typical, high open loop voltage gain, useful bandwidth of 700KHz,
slew rate of 0.7V/ms, and low typical supply current of 120mA.

KEY FEATURES
• EPAD (Electrically Programmable Analog Device)
• User programmable VOS trimmer
• Computer-assisted trimming
• Rail-to-rail input/output
• Compatible with standard EPAD Programmer
• High precision through in-system circuit precision trimming
• Reduces or eliminates VOS, PSRR, CMRR and TCVOS errors
• System level “calibration” capability
• Application Specific Programming mode
• In-System Programming mode
• Electrically programmable to compensate for external
component tolerances
• Achieves 0.01pA input bias current and 35mV input offset
voltage simultaneously
• Compatible with industry standard pinout

BENEFITS
• Eliminates manual and elaborate
system trimming procedures
• Remote controlled automated trimming
• In-System Programming capability
• No external components
• No internal chopper clocking noise
• No chopper dynamic power dissipation
• Simple and cost effective
• Small package size
• Extremely small total functional
volume size
• Low system implementation cost
• Micropower and Low Voltage

APPLICATIONS
• Sensor interface circuits
• Transducer biasing circuits
• Capacitive and charge integration circuits
• Biochemical probe interface
• Signal conditioning
• Portable instruments
• High source impedance electrode
amplifiers
• Precision Sample and Hold amplifiers
• Precision current to voltage converter
• Error correction circuits
• Sensor compensation circuits
• Precision gain amplifiers
• Periodic In-system calibration
• System output level shifter