These MOSFET devices have very low input currents and,
as a result, a very high input impedance (>10
12
Ohm). The
gate voltage from a control source can drive many MOSFET
inputs with practically no loading effects. Used in precision
current mirror or current multiplier applications, they can
be used to provide a current source over a 100nA to 3mA
range, and with either a positive, negative, or zero tempco.
Optional EPAD Threshold Voltage Trimming by User
The basic EPAD MOSFET device is a monotonically
adjustable device, which means the device can normally
be e-trimmed to increase in threshold voltage and to
decrease in drain-on current as a function of a given input
bias voltage. Used as an in-circuit element for trimming or
setting a combination of voltage current and/or on-
resistance characteristics, it can be set up to be e-trimmed
remotely and automatically. Once e-trimmed, the set
voltage and current levels are stored indefinitely inside the
device as a nonvolatile stored charge, which is not affected
during normal operation of the device, even when power is
turned off. A given EPAD device can be adjusted many
times to continually increase its threshold voltage. A pair
of EPAD devices can also be connected differentially such
that one device is used to adjust a parameter in one
direction and the other device is used to adjust the same
parameter in the other direction.
The ALD1121E/ALD1123E can be e-trimmed with an ALD
EPAD programmer to obtain the desired voltage and
current levels. They can also be e-trimmed as an active in-
system element in a user system, via user designed
interface circuitry. P
N1
, P
N2
, etc., are pins required for
optional e-trim of respective MOSFET devices. If unused,
these pins are to be connected to V- or ground. For more
information, see Application Note AN1108.
APPLICATIONS
• Precision PC-based electronic calibration
• Automated voltage trimming or setting
• Remote voltage or current adjustment of
inaccessible nodes
• PCMCIA based instrumentation trimming
• Electrically adjusted resistive load
• Temperature compensated current sources and
current mirrors
• Electrically trimmed/calibrated current sources
• Permanent precision preset voltage level shifter
• Low temperature coefficient voltage and/or current
bias circuits
• Multiple preset voltage bias circuits
• Multiple channel resistor pull-up or pull-down circuits
• Microprocessor based process control systems
• Portable data acquisition systems
• Battery operated terminals and instruments
• Remote telemetry systems
• E-trimmable gain amplifiers
• Low level signal conditioning
• Sensor and transducer bias currents
• Neural networks
BENEFITS (cont.)
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Usable in environmentally sealed circuits
•
No mechanical moving parts -- high G-shock
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tolerance
Improved reliability, dependability, dust and
moisture resistance
Cost and labor savings
Small footprint for high board density
applications
FEATURES
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Electrically Programmable Analog Device
Proven, non-volatile CMOS technology
Operates from 2V, 3V, 5V to 10V
Flexible basic circuit building block and design
element
Very high resolution -- average e-trim voltage
resolution of 0.1mV
Wide dynamic range -- current levels from 0.1µA
to 3000µA
Voltage adjustment range from 1.000V to 3.000V
in 0.1mV steps
Typical 10-year drift of less than 2mV
Usable in voltage mode or current mode
High input impedance -- 1012
Ω
Very high DC current gain -- greater than 109
Device operating current has positive temperature
coefficient range and negative temperature
coefficient range with cross-over zero temperature
coefficient current level at 68µA
Tight matching and tracking of on-resistance
between different devices with e-trim
Very low input currents and leakage currents
Low cost, monolithic technology
Application-specific or in-system programming modes
Optional user software-controlled automation
Optional e-trim of any standard/custom configuration
Micropower operation
Available in standard PDIP, SOIC and hermetic CDIP
packages
Suitable for matched-pair balanced circuit configuration
Suitable for both coarse and fine trimming, as well as
matched MOSFET array applications
RoHS compliant
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ALD1121E/ALD1123E
Advanced Linear Devices
2 of 14
ALD [ ADVANCED LINEAR DEVICES ]
