MAX3228EBV-T Maxim Integrated, MAX3228EBV-T Datasheet - Page 6

• Manufacturer Part Number: MAX3228EBV-T
• Description: RS-232 Interface IC 2.5-5.5V Transceiver
• Manufacturer: Maxim Integrated
• Series: MAX3228, MAX3229r

Specifications of MAX3228EBV-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
• Mounting Style: SMD/SMT
• Package / Case: UCSP-20 6 x 5
• Number Of Drivers: 2
• Number Of Receivers: 2

+2.5V to +5.5V RS-232 Transceivers
in UCSP
Table 1. Operating Supply Options
The MAX3228/MAX3229 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 oper-
ate 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.
6
MAX3228
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
MAX3229
falling)
falling)
C5
C6
D1
E1
E2
E3
E5
Detailed Description
FORCEOFF
INVALID
R_OUT
T_OUT
NAME
GND
R_IN
C1-
Voltage Converter
+2.4 to +4.2
+2.4 to +3.8
+3.0 to +5.5
+2.5 to +3.0
V
CC
FORCEOFF Input, Active-Low. 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)
Negative Terminal of Positive Regulated Charge-Pump Capacitor.
Ground
Output of Valid Signal Detector. 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 MAX3228/MAX3229 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.
Figure 1. V+ Switchover for Changing V
+3.0 to +5.5
+2.5 to +3.0
V
L
(V)
V
FUNCTION
Pin Description (continued)
CC
V+
Voltage Generation in the
20ms/div
Compliant/Compatible
Compliant/Compatible
Switchover Region
RS-232 MODE
CC
Compatible
Compliant
4V
0
6V
0