UM4684 Datasheet, PDF (9/12 Pages) Union Semiconductor, Inc. – 0.5Ω Low-Voltage Dual SPDT Analog Switch

UM4684
Applications Information
Digital Control Inputs
The UM4684 logic inputs accept up to +5.5V regardless of supply voltage. For example, with a
+3.3V supply, IN_ may be driven low to GND and high to 5.5V. Driving IN_ rail-to-rail
minimizes power consumption. Logic levels for a +1.8V supply are 0.5V (low) and 1.4V (high).
Analog Signal Levels
Analog signals that range over the entire supply voltage (V+ to GND) is passed with very little
change in on-resistance (see Typical Operating Characteristics). The switches are bidirectional, so
the NO_, NC_, and COM_ pins can be either inputs or outputs.
Caution
Do not exceed the absolute maximum ratings because stresses beyond the listed ratings may cause
permanent damage to devices.
Proper power-supply sequencing is recommended for all CMOS devices. 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 diode
(D1) as shown in Figure 6. Adding a protection diode reduces the analog range to a diode drop
(about 0.7V) below V+ (for D1). RON increases slightly at low supply voltages. Maximum supply
voltage (V+) must not exceed +6V. Protection diode D1 also protects against some over voltage
situations. No damage will result on Figure 6’s circuit if the supply voltage is below the absolute
maximum rating applied to an analog signal pin.
Figure 6
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