MAX13235EEUP+T Maxim Integrated Products, MAX13235EEUP+T Datasheet - Page 10

• Manufacturer Part Number: MAX13235EEUP+T
• Description: TXRX RS-232 3MBPS 2X2 20TSSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX13235EEUP+T

• Number Of Drivers/receivers: 2/2
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 20-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

3Mbps RS-232 Transceivers with
Low-Voltage Interface
The MAX13234E–MAX13237E feature a separate logic
supply input (V
(V
V
UARTs or communication controllers that have different
logic levels. Connect this input to the host logic supply
(1.62V ≤ V
The internal power supply consists of a regulated dual
charge pump that provides output voltages of +5.5V
and -5.5V (inverting charge pump), over the +3.0V to
+5.5V range. The charge pump operates in discontinu-
ous mode: if the output voltages are less than +5.5V,
the charge pump is enabled; if the output voltages
exceed +5.5V, the charge-pump is disabled. The
charge pumps require flying capacitors (C1, C2) and
reservoir capacitors (C3, C4) to generate the V+ and V-
supplies. The READY output is low when the charge
pumps are disabled in shutdown mode. The READY
signal asserts high when V- goes below -4V.
The transmitters are inverting level translators that con-
vert CMOS-logic levels to ±5.0V EIA/TIA-232 levels.
The MAX13234E/MAX13236E guarantee a 250kbps
data rate with worst-case loads of 3kΩ in parallel with
1000pF. The MAX13235E/MAX13237E guarantee a
1Mbps data rate with worst-case loads of 3kΩ in paral-
lel with 250pF, and a 3Mbps data rate with worst-case
loads of 3kΩ in parallel with 150pF. Transmitters can be
paralleled to drive multiple receivers. When FORCEOFF
is driven to ground or when the AutoShutdown Plus cir-
cuitry senses that all receiver and transmitter inputs are
inactive for more than 30s, the transmitters are disabled
and the outputs go into a high-impedance state. When
powered off or shut down, the outputs can be driven to
±12V. The transmitter inputs do not have pullup resis-
tors. Connect unused inputs to GND or V
10
IH
OH
). This feature allows flexibility in interfacing to
______________________________________________________________________________________
), and sets the transmitter’s input thresholds (V
Dual Charge-Pump Voltage Converter
L
≤ V
CC
L
) that sets the receiver’s output level
).
Detailed Description
VL Logic Supply Input
RS-232 Transmitters
L
.
IL
,
The receivers convert RS-232 signals to CMOS-logic
output levels. The MAX13234E–MAX13237E have
inverting outputs that are active when in shutdown
(FORCEOFF = GND) (Table 1).
Drive FORCEOFF high and FORCEON low to invoke
AutoShutdown Plus mode. When these devices do not
sense a valid signal transition on any receiver and
transmitter input for 30s, the onboard charge pumps
are shut down, reducing supply current to 1µA. This
occurs if the RS-232 cable is disconnected or
if the devices driving the transmitter and receiver
inputs are inactive for more than 30s. The
MAX13234E–MAX13237E turn on again when a valid
transition is applied to any RS-232 receiver or transmit-
ter input. As a result, the system saves power without
requiring any control.
Figure 6 and Table 1 summarize the MAX13234E–
MAX13237E operating modes. The FORCEON and
FORCEOFF inputs override AutoShutdown Plus circuit-
ry. When neither control is asserted, the IC selects
between these states automatically based on the last
receiver or transmitter input edge received.
Drive FORCEOFF low to place the MAX13234E–
MAX13237E into shutdown mode.
Figure 7. AutoShutdown Plus Initial Turn-On to Wake Up a
Mouse or Another System
MANAGEMENT
POWER-
UNIT
Hardware-Controlled Shutdown
MASTER SHDN LINE
AutoShutdown Plus Mode
FORCEOFF
MAX13234E
MAX13235E
MAX13236E
MAX13237E
RS-232 Receivers
0.1µF
FORCEON
1MΩ