LF11201 datasheet(9/18 Pages) NSC

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Application Hints (Continued)

LEAKAGE CURRENTS

The drain and source leakage currents, in both the ON and

the OFF states of each switch, are typically less than 1 nA at

25˚C and less than 100 nA at 125˚C. As shown in the typical

curves, these leakage currents are Dependent on power

supply voltages, analog voltage, analog current and the

source to drain voltage.

DELAY TIMES

The delay time OFF (t

OFF) is essentially independent of both

the analog voltage and temperature. The delay time ON

ON) will decrease as either (VCC−VA) decreases or the tem-

perature decreases.

POWER SUPPLIES

The voltage between the positive supply (V

CC) and either the

negative supply (V

EE) or the reference supply (VR) can be as

much as 36V. To accommodate variations in input logic refer-

ence voltages, V

R can range from VEE to (VCC−4.5V). Care

should be taken to ensure that the power supply leads for the

device never become reversed in polarity or that the device

is never inadvertently installed backwards in a test socket. If

one of these conditions occurs, the supplies would zener an

internal diode to an unlimited current; and result in a de-

stroyed device.

SWITCHING TRANSIENTS

When a switch is turned OFF or ON, transients will appear at

the load due to the internal transient voltage at the gate of

the switch JFET being coupled to the drain and source by

the junction capacitances of the JFET. The magnitude of

these transients is dependent on the load. A lower value R

produces a lower transient voltage. A negative transient oc-

curs during the delay time ON, while a positive transient oc-

curs during the delay time OFF. These transients are rela-

tively small when compared to faster switch families.

DISABLE NODE

This node can be used, as shown in

Figure 5, to turn all the

switches in the unit off independent of logic inputs. Normally,

the node floats freely at an internal diode drop (

≈0.7V) above

R. When the external transistor in Figure 5 is saturated, the

node is pulled very close to V

R and the unit is disabled. Typi-

cally, the current from the node will be less than 1 mA. This

feature is not available on the LF11201 or LF11202 series.

Typical Applications

DS005667-6

FIGURE 5. Disable Function

Sample and Hold with Reset

DS005667-42

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