MAX3226EAAE+T Maxim Integrated, MAX3226EAAE+T Datasheet - Page 6

• Manufacturer Part Number: MAX3226EAAE+T
• Description: RS-232 Interface IC
• Manufacturer: Maxim Integrated
• Series: MAX3224E, MAX3225E, MAX3226E, MAX3227E, MAX3244E, MAX3245Er

Specifications of MAX3226EAAE+T

• Data Rate: 250 Kbps
• Operating Supply Voltage: 3 V to 5.5 V
• Supply Current: 1 mA
• Operating Temperature Range: 0 C to + 70 C
• Function: Transceiver
• Number Of Drivers: 1
• Number Of I/os: 4
• Number Of Receivers: 1
• Propagation Delay Time Ns: 0.15 us
• Shutdown: Yes

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
The MAX3230E/AE and MAX3231E/AE internal power
supply consists of a dual-mode regulated charge
pump. For supply voltages above +3.7V, the charge
pump generates +5.5V at V+ and -5.5V at V-. The
charge pumps operate in a discontinuous mode. If the
output voltages are less than ±5.5V, the charge pumps
are enabled. If the output voltages exceed ±5.5V, the
charge pumps are disabled.
For supply voltages below +2.85V, the charge pump
generates +4.0V at V+ and -4.0V at V-. The charge
pumps operate in a discontinuous mode. If the output
voltages are less than ±4.0V, the charge pumps are
enabled. If the output voltages exceed ±4.0V, the
charge pumps are disabled.
Each charge pump requires a flying capacitor (C1, C2)
and a reservoir capacitor (C3, C4) to generate the V+
and V- supply voltages.
The MAX3230E/AE and MAX3231E/AE include a
switchover circuit between these two modes that have
approximately 400mV of hysteresis around the
switchover point. The hysteresis is shown in Figure 1.
This large hysteresis eliminates mode changes due to
power-supply bounce.
For example, a three-cell NiMh battery system starts at
V
put voltage of ±5.5V. As the battery discharges, the
MAX3230E/AE and MAX3231E/AE maintain the outputs
Dual Mode is a trademark of Maxim Integrated Products, Inc.
6
MAX3230AE
MAX3230E/
CC
C6, D6
E3, E4
E5, E6
_______________________________________________________________________________________
= +3.6V, and the charge pump generates an out-
D1
E1
E2
—
Dual Mode™ Regulated Charge-Pump
BUMP
MAX3231AE
MAX3231E/
B6, D6, E4,
C6
D1
E1
E2
E3
E5
E6
Detailed Description
Voltage Generation in the
INVALID
R_OUT
T_OUT
NAME
GND
R_IN
N.C.
C1-
Switchover Region
Voltage Converter
Receiver Output(s)
Positive Regulated Charge-Pump Capacitor Negative Terminal
Ground
Valid Signal-Detector Output. Output INVALID is enabled low if no valid RS-232 level is
present on any receiver input.
RS-232 Transmitter Output(s)
RS-232 Receiver Input(s)
No Connection. These locations are populated with solder bumps, but are electrically
isolated.
in regulation until the battery voltage drops below +3.1V.
The output regulation points then change to ±4.0V.
When V
put voltage of ±4.0V, while V
+3.5V. When V
+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
convert CMOS logic levels to RS-232 levels. The
MAX3230E/AE and MAX3231E/AE automatically reduce
the RS-232-compliant levels (±5.5V) to RS-232-compat-
ible levels (±4.0V) when V
+3.1V. The reduced levels also reduce supply-current
requirements, extending battery life. Built-in hysteresis
of approximately 400mV for V
Figure 1. V+ Switchover for Changing V
CC
V
CC
V+
is rising, the charge pump generates an out-
Pin Description (continued)
FUNCTION
CC
rises above the switchover voltage of
20ms/div
CC
RS-232 Transmitters
CC
falls below approximately
CC
is between +2.5V and
ensures that the RS-
CC
4V
0
6V
0