MAX3228AEEWV+T Maxim Integrated, MAX3228AEEWV+T Datasheet - Page 7

• Manufacturer Part Number: MAX3228AEEWV+T
• Description: RS-232 Interface IC +2.5V to +5.5V RS-232 Tranceivers in UCSP
• Manufacturer: Maxim Integrated
• Series: MAX3228AE, MAX3228E, MAX3229AE, MAX3229Er

Specifications of MAX3228AEEWV+T

• Data Rate: 250 Kbps
• Operating Supply Voltage: 2.5 V to 5.5 V
• Supply Current: 10 uA
• Operating Temperature Range: - 40 C to + 85 C
• Number Of Drivers: 2
• Number Of Receivers: 2

MAX3228E/AE and MAX3229E/AE maintain the outputs
in regulation until the battery voltage drops below +3.1V.
Then the output regulation points change to ±4.0V
When V
output voltage of ±4.0V, while V
and +3.5V. When V
age of +3.5V, the charge pump switches modes to
generate an output of ±5.5V.
Table 1 shows different supply schemes and their oper-
ating voltage ranges.
The transmitters are inverting level translators that con-
vert CMOS-logic levels to RS-232 levels. The
MAX3228E/AE and MAX3229E/AE will automatically
reduce the RS-232 compliant levels (±5.5V) to RS-232
compatible levels (±4.0V) when V
approximately +3.1V. The reduced levels also reduce
supply current requirements, extending battery life.
Built-in hysteresis of approximately 400mV for V
ensures that the RS-232 output levels do not change if
V
supply voltage to drop slightly. The outputs will return to
RS-232 compliant levels (±5.5V) when V
approximately +3.5V.
The MAX3228E/AE and MAX3229E/AE transmitters
guarantee a 250kbps data rate with worst-case loads of
3kΩ in parallel with 1000pF.
When FORCEOFF is driven to ground, the transmitters
and receivers are disabled and the outputs become
high impedance. When the AutoShutdown circuitry
senses that all receiver and transmitter inputs are inac-
tive for more than 30µs, the transmitters are disabled
and the outputs go to a high-impedance state. When
the power is off, the MAX3228E/AE and MAX3229E/AE
permit the transmitter outputs to be driven up to ±12V.
Figure 2a. MAX322_E Entering 1µA Supply Mode via
AutoShutdown
CC
+0.3V
-0.3V
R_IN
*TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO 1μA IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR AT LEAST 30μs.
is noisy or has a sudden current draw causing the
CC
is rising, the charge pump will generate an
_______________________________________________________________________________________
CC
RS-232 Transceivers in UCSP and WLP
rises above the switchover volt-
±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transmitters
CC
COUNTER
30μs
is between +2.5V
R
CC
CC
AND TRANSMITTERS
falls below
rises above
POWER SUPPLY
INVALID
TO MAX322 _E
CC
The transmitter inputs do not have pullup resistors.
Connect unused inputs to GND or V
The MAX3228E/AE and MAX3229E/AE receivers con-
vert RS-232 signals to logic output levels. All receivers
have inverting three-state outputs and can be active or
inactive. In shutdown (FORCEOFF = low) or in
AutoShutdown, the MAX3228E/AE and MAX3229E/AE
receivers are in a high-impedance state (Table 3).
The MAX3228E/AE and MAX3229E/AE feature an
INVALID output that is enabled low when no valid
RS-232 signal levels have been detected on any
receiver inputs. INVALID is functional in any mode
(Figures 2 and 3).
Figure 2b. MAX322_E with Transmitters Enabled Using
AutoShutdown
Figure 2c. MAX322_E AutoShutdown Logic
+2.7V
-2.7V
R_IN
*TRANSMITTERS ARE ENABLED IF:
ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V.
ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR LESS THAN 30μs.
V
INVALID IS AN INTERNALLY GENERATED SIGNAL
THAT IS USED BY THE AUTOSHUTDOWN LOGIC
AND APPEARS AS AN OUTPUT OF THE DEVICE.
POWER DOWN IS ONLY AN INTERNAL SIGNAL.
IT CONTROLS THE OPERATIONAL STATUS OF
THE TRANSMITTERS AND THE POWER SUPPLIES.
CC
V
L
FORCEOFF
FORCEON
INVALID
V
L
RS-232 Receivers
COUNTER
L
30μs
.
R
POWER DOWN
POWER SUPPLY
INVALID
TO MAX322 _E
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