MAX3228AE MAXIM [Maxim Integrated Products], MAX3228AE Datasheet - Page 9

• Manufacturer Part Number: MAX3228AE
• Manufacturer: MAXIM [Maxim Integrated Products]

MAX3228E/AE and MAX3229E/AE feature a separate
logic supply input (V
and INVALID outputs. The transmitter inputs (T_IN),
FORCEON and FORCEOFF, are also referred to V
This feature allows maximum flexibility in interfacing to
different systems and logic levels. Connect V
system’s logic supply voltage (+1.65V to +5.5V), and
bypass it with a 0.1µF capacitor to GND. If the logic
supply is the same as V
enable V
be greater than or equal to the V
If direct software control is desired, connect FORCE-
OFF and FORCEON together to disable AutoShutdown.
The microcontroller then drives FORCEOFF and
FORCEON like a SHDN input, INVALID can be used to
alert the microcontroller to indicate serial data activity.
As with all Maxim devices, ESD-protection structures are
incorporated on all pins to protect against electrostatic
discharges encountered during handling and assembly.
The driver outputs and receiver inputs of the
MAX3228E/AE and MAX3229E/AE have extra protection
against static electricity. Maxim’s engineers have devel-
oped state-of-the-art structures to protect these pins
against ESD of ±15kV without damage. The ESD struc-
tures withstand high ESD in all states: normal operation,
shutdown, and powered down. After an ESD event
Maxim’s E versions keep working without latchup,
whereas competing RS-232 products can latch and
must be powered down to remove latchup.
ESD protection can be tested in various ways; the trans-
mitter outputs and receiver inputs of this product family
are characterized for protection to the following limits:
1) ±15kV using the Human Body Model.
3) ±15kV using the IEC 1000-4-2 Air-Gap method.
2) ±8kV using the Contact Discharge method specified
Table 3. Output Control Truth Table
X = Don’t care.
† = INVALID output state is determined by R_IN input levels.
Shutdown (AutoShutdown)
Shutdown (Forced Off)
Normal Operation (Forced On)
Normal Operation (AutoShutdown)
in IEC 1000-4-2.
TRANSCEIVER STATUS
CC
before enabling the V
Software-Controlled Shutdown
_______________________________________________________________________________________
L
RS-232 Transceivers in UCSP and WLP
) that sets V
CC
±15kV ESD-Protected +2.5V to +5.5V
, connect V
±15kV ESD Protection
L
supply.
L
OH
supply. V
FORCEON
L
for the receiver
to V
High
Low
Low
X
CC
CC
. Always
L
to the
must
L
.
FORCEOFF
ESD performance depends on a variety of conditions.
Contact Maxim for a reliability report that documents test
setup, test methodology, and test results.
Figure 5a shows the Human Body Model, and Figure 5b
shows the current waveform it generates when dis-
charged into a low impedance. This model consists of a
100pF capacitor charged to the ESD voltage of interest,
which is then discharged into the test device through a
1.5kΩ resistor.
Figure 5a. Human Body ESD Test Models
Figure 5b. Human Body Model Current Waveform
AMPERES
High
High
High
Low
VOLTAGE
SOURCE
HIGH-
DC
I
P
36.8%
100%
90%
10%
0
CHARGE-CURRENT
LIMIT RESISTOR
0
R
t
RL
C
RECEIVER STATUS
1MΩ
100pF
C s
High-Z
High-Z
Active
Active
CURRENT WAVEFORM
STORAGE
CAPACITOR
TIME
R
RESISTANCE
D
DISCHARGE
1500Ω
t
DL
I r
ESD Test Conditions
Human Body Model
PEAK-TO-PEAK RINGING
(NOT DRAWN TO SCALE)
INVALID
H
L
†
†
DEVICE
UNDER
TEST
9