MAX3320ACAP+T Maxim Integrated Products, MAX3320ACAP+T Datasheet - Page 6

• Manufacturer Part Number: MAX3320ACAP+T
• Description: IC TXRX RS232 250KBPS 20-SSOP
• Manufacturer: Maxim Integrated Products
• Type: Transceiverr

Specifications of MAX3320ACAP+T

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

3V to 5.5V, up to 250kbps True RS-232 Transceiver
with 4µA AutoShutdown Plus and Power-On Reset
______________ Detailed Description
The MAX3320’s internal power supply consists of a reg-
ulated dual charge pump that provides output voltages
of +5.5V (doubling charge pump) and -5.5V (inverting
charge pump) while V
range. The charge pumps operate in discontinuous
mode; they are enabled if the output voltages are less
than 5.5V, and disabled if output voltages exceed 5.5V.
Each charge pump requires a flying capacitor (C1, C2)
and a reservoir capacitor (C3, C4) to generate the V+
and V- supplies.
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5V EIA/TIA-232 levels. The
MAX3320 transmitters guarantee a 250kbps data rate
with worst-case loads of 3k
providing compatibility with PC-to-PC communication
software (such as LapLink™). Transmitters can be par-
alleled to drive multiple receivers. Figure 1 shows a
complete system connection.
When FORCEOFF is driven to ground, the transmitter’s
outputs become high impedance. When the
AutoShutdown Plus circuitry senses that all receiver
and transmitter inputs are inactive for more than 30sec,
the transmitters turn off and the outputs go into a high-
impedance state, but the receivers remain active.
When the power is off or the MAX3320 is shut down,
outputs may be driven up to ±12V.
The transmitter inputs do not have pull-up resistors.
Connect unused inputs to GND or V
Laplink is a trademark of Traveling Software.
Table 1. MAX3320 Output Control Truth Table
X = Don’t Care
* Time since last receiver or transmitter input activity
6
_______________________________________________________________________________________
FORCEON
Dual Charge-Pump Voltage Converter
X
1
0
0
CC
FORCEOFF
remains in the 3V to 5.5V
RS-232 Transmitters
0
1
1
1
in parallel with 1000pF,
CC
.
AUTOSHUTDOWN
<30sec*
>30sec*
PLUS*
X
X
The receivers convert RS-232 signals to CMOS-logic out-
put levels. All receivers have inverting outputs and are
active in shutdown FORCEOFF (Table 1).
Maxim’s AutoShutdown Plus feature, which operates
when FORCEOFF is high and FORCEON is low, achieves
a 4µA supply current. When the MAX3320 senses no
valid signal levels on all receiver and transmitter inputs for
30sec, the on-board power supply and drivers shut off,
Figure 1. Interface Under Control of PMU
MANAGEMENT
CONTROLLER
CPU
(AutoShutdown Plus)
(AutoShutdown Plus)
KEYBOARD
POWER-
UNIT OR
Normal operation
Normal operation
OPERATION
(forced off)
(forced on)
Shutdown
Shutdown
STATUS
INVALID
FORCEOFF
FORCEON
WITH
UART
CHIP
I/O
AutoShutdown Plus Mode
T_OUT
High-Z
High-Z
Active
Active
RS-232 Receivers
MAX3320
T1
T2
R1
R2
R_OUT
Active
Active
Active
Active
RS-232