Rainbow Electronics MAX4912 User Manual

Page 9

MAX4910/MAX4911/MAX4912

Quad-SPDT, Clickless Audio Switches

with Negative Signal Handling

_______________________________________________________________________________________

Analog Signal Levels

The MAX4910/MAX4911/MAX4912 on-resistance is
channel dependant. Channels 1 and 3 have an on-
resistance of 0.37

Ω (typ), and channels 2 and 4 have

an on-resistance of 0.72

Ω (typ). The on-resistance flat-

ness is guaranteed over temperature and shows mini-
mal variation over the entire voltage supply range (see
the Typical Operating Characteristics). The on-resis-
tance flatness and low-leakage features make it ideal
for bidirectional operation. The switches are bidirection-
al, so the NO_, NC_, and COM_ pins can be either
inputs or outputs.

These devices pass signals as low as V

- 5.5V,

including signals below ground with minimal distortion.

Click-and-Pop Suppression

The MAX4910/MAX4911 have a 3.8k

Ω (typ) shunt resis-

tor on all their NO and NC terminals to automatically
discharge any capacitance when they are not connect-
ed to COM. The MAX4912 has shunt resistors on all
NO, NC1, and NC3 terminals. The shunt resistors
reduce audible click-and-pop sounds that occur when
switching between audio sources.

Audible clicks and pops are caused when a step DC
voltage is switched into the speaker. The DC step tran-

sients can be reduced by automatically discharging the
side that is not connected to the COM terminal, reducing
any residual DC voltage and reducing clicks and pops.

Break-Before-Make Switching

The MAX4910/MAX4911/MAX4912 feature break-
before-make switching, which is configured to break
(open) the first set of contacts before engaging (clos-
ing) the new contacts. This prevents the momentary
connection of the old and new signal paths to the out-
put, reducing click-and-pop sounds.

Power-Supply Sequencing and

Overvoltage Protection

Caution: Do not exceed the Absolute Maximum
Ratings since stresses beyond the listed ratings
may cause permanent damage to the device.

Proper power-supply sequencing is recommended for
all CMOS devices. Improper supply sequencing can
force the switch into latchup causing it to draw exces-
sive supply current. The only way out of latchup is to
recycle the power and properly reapply it. Connect all
ground pins first, then apply power to V

, and finally

apply signals to NO_, NC_, and COM_. Follow the
reverse order upon power-down.

GND

1.8V TO 5.5V

NO2

COM2

NC4

NO4

COM4

NC2

VOICE

AMP

MELODY IC

CODEC

MP3

CB1 (CB)

DISCHARGE

CONTROL/

SIGNAL CONTROL

CB2 (EN)

NO1

COM1

NC3

NC1

NO3

COM3

SPEAKER 8

Ω

MAX4910
MAX4911
MAX4912

( ) IS FOR MAX4911 ONLY

Figure 1. Typical Application Circuit