(C1 to other capacitors).

When using the minimum-required capacitor values,

make sure the capacitor value does not degrade exces-

sively with temperature. If in doubt, use capacitors with

a higher nominal value. The capacitor’s equivalent

series resistance (ESR), which usually rises at low tem-

peratures, influences the amount of ripple on V+ and V-.

Power-Supply Decoupling

In most circumstances, a 0.1µF bypass capacitor is

adequate. In applications that are sensitive to power-

of the same value as charge pump capacitor C1.

Connect bypass capacitors as close to the IC as possible.

Transmitter Outputs when

Exiting Shutdown

Figure 2 shows two transmitter outputs when exiting

shutdown mode. As they become active, the two trans-

mitter outputs are shown going to opposite RS-232-

compatible levels (one transmitter input is high, the

other is low). Each transmitter is loaded with 3k

Ω in par-

2.5V, 1µA, 460kbps,

RS-232-Compatible Transceivers

______________________________________________________________________________________

11

FORCEON

MASTER SHDN LINE

0.1

µF1MΩ

FORCEOFF

MAX3318

MAX3319

POWER-

MANAGEMENT

UNIT

Figure 5. AutoShutdown Plus Initial Turn-On to Wake Up a

Mouse or Another System

0

0

V+

V-

0

INVALID

OUTPUT

READY

OUTPUT

TRANSMITTER

INPUTS

RECEIVER

INPUTS

}

INVALID

REGION

*MAX3318/MAX3319

TRANSMITTER

OUTPUTS

Figure 4b. AutoShutdown Plus, INVALID, and READY Timing Diagram