Power-Supply Sequencing

and Overvoltage Protection

Do not exceed the absolute maximum ratings because

stresses beyond the listed ratings may cause perma-

nent damage to the devices.

Proper power-supply sequencing is recommended for

all CMOS devices. Always apply V+ before applying

analog signals or logic inputs, especially if the analog

or logic signals are not current limited. If this sequenc-

ing is not possible, and if the analog or logic inputs are

not current limited to <10mA, add a small-signal diode

(D1) as shown in Figure 1. If the analog signal can dip

below GND, add D2. Adding protection diodes

reduces the analog signal range to a diode drop (about

0.7V) below V+ (for D1), and to a diode drop above

ground (for D2). Leakage is unaffected by adding the

diodes. On-resistance increases by a small amount at

low supply voltages. Maximum supply voltage (V+)

must not exceed 13V.

Adding protection diodes causes the logic thresholds

to be shifted relative to the power-supply rails. This can

be significant when low supply voltages (+5V or less)

are used. With a +5V supply, TTL compatibility is not

guaranteed when protection diodes are added. Driving

IN1 and IN2 all the way to the supply rails (i.e., to a

diode drop higher than the V+ pin, or to a diode drop

lower than the GND pin) is always acceptable.

Protection diodes D1 and D2 also protect against

some overvoltage situations. With Figure 1’s circuit, if

the supply voltage is below the absolute maximum rat-

ing, and if a fault voltage up to the absolute maximum

rating is applied to an analog signal pin, no damage

will result.

Low-Voltage, Single-Supply

Dual SPST/SPDT Analog Switches

_______________________________________________________________________________________

7

tr < 20ns

tf < 20ns

50%

0

LOGIC

INPUT

1k

COM

GND

(

)

SWITCH

INPUT

IN

+3V

0

NO

or NC

SWITCH

OUTPUT

0.9

0.9

SWITCH

OUTPUT

LOGIC

INPUT

LOGIC INPUT WAVEFORMS INVERTED FOR SWITCHES

THAT HAVE THE OPPOSITE LOGIC SENSE.

V+

35pF

V+

0V

MAX4541

MAX4542

MAX4543

MAX4544

Figure 2. Switching Time

Test Circuits/Timing Diagrams