GENERAL DESCRIPTION

ALD114804A/ALD114804/ALD114904A/ALD114904 are high precision monolithic

quad/dual depletion mode N-Channel MOSFETs matched at the factory using

ALD’s proven EPAD? CMOS technology. These devices are intended for low

voltage, small signal applications. They are excellent functional replacements for

normally-closed relay applications, as they are normally on (conducting) without

any power applied, but could be turned off or modulated when system power

supply is turned on. These MOSFETS have the unique characteristics of, when

the gate is grounded, operating in the resistance mode for low drain voltage levels

and in the current source mode for higher voltage levels and providing a constant

drain current.

ALD114804A/ALD114804/ALD114904A/ALD114904 MOSFETs are designed for

exceptional device electrical characteristics matching. As these devices are on

the same monolithic chip, they also exhibit excellent temperature tracking characteristics.

They are versatile as design components for a broad range of analog

applications, such as basic building blocks for current sources, differential amplifier

input stages, transmission gates, and multiplexer applications. Besides

matched pair electrical characteristics, each individual MOSFET also exhibits well

controlled parameters, enabling the user to depend on tight design limits corresponding

to well matched characteristics.

These depletion mode devices are built for minimum offset voltage and differential

thermal response, and they are suitable for switching and amplifying applications

in single supply (0.4V to +5V) or dual supply (+/-0.4V to +/-5V) systems

where low input bias current, low input capacitance and fast switching speed are

desired. These devices exhibit well controlled turn-off and sub-threshold

charactersitics and therefore can be used in designs that depend on sub-threshold

characteristics.

The ALD114804A/ALD114804/ALD114904A/ALD114904 are suitable for use in

precision applications which require very high current gain, beta, such as current

mirrors and current sources. A sample calculation of the DC current gain at a drain

current of 3mA and input leakage current of 30pA at 25°C is 3mA/30pA =

100,000,000. For most applications, connect the V+ pin to the most positive voltage

and the V- and IC pins to the most negative voltage in the system. All other

pins must have voltages within these voltage limits at all times.

ORDERING INFORMATION (“L” suffix denotes lead-free (RoHS))

? Depletion mode (normally ON)

? Precision Gate Threshold Voltages: -0.40V +/-0.02V

? Nominal RDS(ON) @ VGS = 0.0V of 5.4KΩ

? Matched MOSFET-to-MOSFET characteristics

? Tight lot-to-lot parametric control

? Low input capacitance

? VGS(th) match (VOS) — 20mV

? High input impedance — 1012Ω typical

? Positive, zero, and negative VGS(th) temperature coefficient

? DC current gain >108

? Low input and output leakage currents

FEATURES

VAPPLICATIONS

? Functional replacement of Form B (NC) relays

? Ultra low power (nanowatt) analog and digital

circuits

? Ultra low operating voltage (<0.2V) analog and

digital circuits

? Sub-threshold biased and operated circuits

? Zero power fail safe circuits in alarm systems

? Backup battery circuits

? Power failure and fail safe detector

? Source followers and high impedance buffers

? Precision current mirrors and current sources

? Capacitives probes and sensor interfaces

? Charge detectors and charge integrators

? Differential amplifier input stage

? High side switches

? Peak detectors and level shifters

? Sample and Hold

? Current multipliers

? Discrete analog switches and multiplexers

? Discrete voltage comparators