Low-Voltage, High-Speed, Quad, SPST CMOS Analog SwitchesMAX4614/MAX4615/MAX4616

Applications Information

Power-Supply Sequencing and

Overvoltage Protection

Do not exceed the absolute maximum ratings becausestresses beyond the listed ratings may cause perma-nent damage to the devices.

Proper power-supply sequencing is recommended forall CMOS devices. Always apply V+ before applyinganalog signals or logic inputs, especially if the analogor logic signals are not current limited. If this sequenc-ing is not possible, and if the analog or logic inputs arenot current limited to 20mA, add a small-signal diode(D1) as shown in Figure 1. If the analog signal can dipbelow GND, add D2. Adding protection diodesreduces the analog signal range to a diode drop (about0.7V) below V+ (for D1), and to a diode drop aboveground (for D2). Leakage is unaffected by adding thediodes. On-resistance increases by a small amount atlow supply voltages. Maximum supply voltage (V+)must not exceed 6V.

Adding protection diodes causes the logic thresholdsto be shifted relative to the power-supply rails. This canbe significant when low supply voltages (+5V or less)are used. With a +5V supply, TTL compatibility is notguaranteed when protection diodes are added. DrivingIN1 and IN2 all the way to the supply rails (i.e., to a

Figure 1. Overvoltage Protection Using Two External BlockingDiodes

diode drop higher than the V+ pin, or to a diode droplower than the GND pin) is always acceptable.

Protection diodes D1 and D2 also protect against someovervoltage situations. With Figure 1’s circuit, if the sup-ply voltage is below the absolute maximum rating, andif a fault voltage up to the absolute maximum rating isapplied to an analog signal pin, no damage will result.

______________________________________________Test Circuits/Timing Diagrams

Figure 2. Switching Time8

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