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AS1746

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Digital Control Inputs

The AS1746 logic inputs can handle up to +5.5V regardless of the supply voltage. For example, with a +3.3V supply,

INx may be driven low to GND and high to 5.5V. Driving INx rail-to-rail minimizes power consumption.

Analog Signal Levels

Typical Operating Characteristics on page 6). The switches are bi-directional, so the NOx, NCx, and COMx pins can be

used as inputs or outputs.

Power Supply Sequencing

Proper power supply sequencing is recommended for all CMOS devices. The recommended sequence is as follows:

1. V+

2. NOx, NCx, COMx

Always apply V+ before applying analog signals, especially if the analog signal is not current limited. If this sequencing

is not possible, and if the analog inputs are not current limited to <20mA, add a small signal protection diode (D1) as

shown in Figure 16.

Overvoltage Protection

Using a protection diode will reduce the analog range to a diode voltage drop (approximately 0.7V) below V+ (for D1).

Caution: The maximum supply voltage (V+) must not exceed +7V. Do not exceed the absolute maximum ratings

because stresses beyond the ratings listed in Absolute Maximum Ratings on page 3 may cause permanent

damage to the device.

Note: Protection diode D1 can also protect the device from some overvoltage conditions.

Figure 16. Overvoltage Protections using 2 External Blocking Diodes

Note: No damage will result to the circuit shown in Figure 16 if the supply voltage is below the absolute maximum rat-

ing applied to an analog signal pin (NOx, NCx, or COMx).

AS1746

GND

NO

D1

V+

Positive

Supply

COM