MAX3228AEEWV+T Maxim Integrated, MAX3228AEEWV+T Datasheet - Page 6

• 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

±15kV ESD-Protected +2.5V to +5.5V
RS-232 Transceivers in UCSP and WLP
The MAX3228E/AE and MAX3229E/AE internal power
supply consists of a dual-mode regulated charge
pump. For supply voltages above +3.7V, the charge
pump will generate +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
will generate +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.
Table 1. Operating Supply Options
6
MAX3228AE
MAX3228E/
C6, D6
E3, E4
E5, E6
_______________________________________________________________________________________
C5
D1
E1
E2
Regulated Voltage Only
Regulated Voltage Only
SYSTEM SUPPLY (V)
3 NiCad/NiMh Cells
Dual-Mode Regulated Charge-Pump
(V
(V
PIN
1 Li+ Cell
CC
CC
MAX3229AE
MAX3229E/
falling)
falling)
C5
C6
D1
E1
E2
E3
E5
Detailed Description
Voltage Generation in the
FORCEOFF
INVALID
R_OUT
T_OUT
NAME
GND
R_IN
C1-
Switchover Region
Voltage Converter
+2.4 to +4.2
+2.4 to +3.8
+3.0 to +5.5
+2.5 to +3.0
V
CC
Active-Low FORCEOFF Input. Drive FORCEOFF low to shut down transmitters,
receivers, and on-board charge pump. This overrides all automatic circuitry and
FORCEON. Pulls itself high internally if not connected.
Receiver Output(s)
Positive Regulated Charge-Pump Capacitor Negative Terminal
Ground
Valid Signal Detector 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)
(V)
Regulated System Voltage
Regulated System Voltage
The MAX3228E/AE and MAX3229E/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
output voltage of ±5.5V. As the battery discharges, the
Figure 1. V+ Switchover for Changing V
CC
+3.0 to +5.5
+2.5 to +3.0
V
= +3.6V, and the charge pump will generate an
L
(V)
V
CC
V+
FUNCTION
Pin Description (continued)
20ms/div
Compliant/Compatible
Compliant/Compatible
RS-232 MODE
CC
Compatible
Compliant
4V
0
6V
0