|
|
PDF MAX3238EAI Data sheet ( Hoja de datos )
| Número de pieza | MAX3238EAI | |
| Descripción | +3.0V to +5.5V / 1A / up to 250kbps / True RS-232 Transceiver with AutoShutdown Plus | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de MAX3238EAI (archivo pdf) en la parte inferior de esta página. Total 12 Páginas | ||
|
No Preview Available !
19-1144; Rev 0; 9/96
+3.0V to +5.5V, 1µA, up to 250kbps, True
RS-232 Transceiver with AutoShutdown Plus™
_______________General Description
The MAX3238 true RS-232 transceiver achieves a
1µA supply current with Maxim’s revolutionary
AutoShutdown Plus feature. When the device does not
sense a valid signal transition on either the receiver or
transmitter inputs within 30sec, the on-board power
supply and drivers shut down. This occurs if the RS-232
cable is disconnected or if the transmitters of the con-
nected peripheral are inactive. The system turns on
again when a valid transition is applied to any RS-232
receiver or transmitter input, saving power without
changes to the existing BIOS or operating system.
The MAX3238 5-driver/3-receiver complete serial port is
a 3V-powered EIA/TIA-232 and V.28/V.24 communica-
tions interface intended for notebook or subnotebook
computer applications. A proprietary, high-efficiency,
dual charge-pump power supply and a low-dropout
transmitter combine to deliver true RS-232 performance
from a single +3.0V to +5.5V supply. A guaranteed
data rate of 250kbps provides compatibility with popu-
lar software for communicating with personal comput-
ers. The MAX3238 requires only 0.1µF capacitors in
3.3V operation. It is ideal for 3.3V-only systems, mixed
3.3V and 5.0V systems, or 5V-only systems that require
true RS-232 performance.
Receiver R1 has an extra, always-active output (in addi-
tion to its standard output), which allows external
devices, such as a modem, to be monitored without for-
ward biasing the protection diodes in circuitry that may
have VCC completely removed.
The MAX3238 is available in a space-saving SSOP
package.
________________________Applications
Notebook, Subnotebook, and Palmtop
Computers
High-Speed Modems
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Printers
Typical Operating Circuit appears at end of data sheet.
AutoShutdown Plus is a trademark of Maxim Integrated Products.
*Patents Pending
____________________________Features
o 1µA Supply Current Achieved with
AutoShutdown Plus
o Guaranteed Data Rate: 250kbps
o 1µA Low-Power Shutdown
o Receivers Active in AutoShutdown Plus Mode
o Flow-Through Pinout
o Meets EIA/TIA-232 Specifications Down to 3.0V
o Guaranteed 6V/µs Slew Rate
______________Ordering Information
PART
MAX3238CAI
MAX3238EAI
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
28 SSOP
28 SSOP
__________________Pin Configuration
TOP VIEW
C2+ 1
GND 2
C2- 3
V- 4
T1OUT 5
T2OUT 6
T3OUT 7
R1IN 8
R2IN 9
T4OUT 10
R3IN 11
T5OUT 12
FORCEON 13
FORCEOFF 14
MAX3238
SSOP
28 C1+
27 V+
26 VCC
25 C1-
24 T1IN
23 T2IN
22 T3IN
21 R1OUT
20 R2OUT
19 T4IN
18 R3OUT
17 T5IN
16 R1OUTB
15 INVALID
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
1 page  
+3.0V to +5.5V, 1µA, up to 250kbps, True
RS-232 Transceiver with AutoShutdown Plus™
Table 1. Output Control Truth Table
FORCEON
FORCEOFF
AUTOSHUTDOWN
PLUS*
OPERATION
STATUS
X0
X
Shutdown
(Forced Off)
11
X
Normal Operation
(Forced On)
Normal
0
1
<30sec*
Operation
(AutoShutdown
Plus)
Shutdown
0
1
>30sec*
(AutoShutdown
Plus)
X = Don’t Care
* Time since last receiver or transmitter input transition.
T_OUT
High-Z
Active
Active
High-Z
R_OUT
High-Z
Active
Active
Active
R1OUTB
Active
Active
Active
Active
_______________Detailed Description
Dual Charge-Pump Voltage Converter
The MAX3238’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), regardless of the input voltage (VCC)
over the 3.0V to 5.5V range. 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.
Each charge pump requires a flying capacitor (C1, C2)
and a reservoir capacitor (C3, C4) to generate the V+
and V- supplies.
RS-232 Transmitters
The transmitters are inverting level translators that con-
vert CMOS-logic levels to 5.0V EIA/TIA-232 levels. The
MAX3238 transmitters guarantee a 250kbps data rate
with worst-case loads of 3kΩ in parallel with 1000pF,
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 transmitters
and receivers are disabled and the outputs go high
impedance, except for R1OUTB. When the Auto-
Shutdown Plus circuitry senses that all receiver and
transmitter inputs are inactive for more than 30sec, the
transmitters are disabled and the outputs go into a
high-impedance state, but the receivers remain active.
When the power is off, the MAX3238 permits the out-
puts to be driven up to ±12V.
The transmitter inputs do not have pull-up resistors.
Connect unused inputs to GND or VCC.
RS-232 Receivers
The receivers convert RS-232 signals to CMOS-logic
output levels. All receivers have inverting three-state
outputs and are inactive in shutdown (FORCEOFF)
(Table 1). The MAX3238 also features an extra, always-
active noninverting output, R1OUTB. This extra output
monitors receiver activity while the other receivers are
high impedance, allowing Ring Indicator to be moni-
tored without forward biasing other devices connected
to the receiver outputs. This is ideal for systems where
VCC is set to 0V in shutdown to accommodate peripher-
als, such as UARTs (Figure 2).
LapLink is a trademark of Traveling Software.
_______________________________________________________________________________________ 5
5 Page 
+3.0V to +5.5V, 1µA, up to 250kbps, True
RS-232 Transceiver with AutoShutdown Plus™
__________Typical Operating Circuit
0.1µF
0.1µF
0.1µF
28 C1+
25 C1-
1 C2+
3 C2-
26
VCC
MAX3238
V+ 27
*
0.1µF
V- 4
0.1µF
LOGIC
INPUTS
24 T1IN
T1 T1OUT 5
23 T2IN
T2 T2OUT 6
22 T3IN
T3 T3OUT 7
19 T4IN
T4 T4OUT 10
17 T5IN
T5 T5OUT 12
14 FORCEOFF
AUTOSHUTDOWN PLUS
13 FORCEON
INVALID 15
16 R1OUTB
RS-232
OUTPUTS
21 R1OUT
LOGIC
OUTPUTS
20 R2OUT
R1
R2
18 R3OUT
R3
R1IN 8
5k
R2IN 9
5k
RS-232
INPUTS
R3IN 11
5k
GND
2
*C3 MAY BE RETURNED TO EITHER VCC OR GND.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet MAX3238EAI.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| MAX3238EAI | +3.0V to +5.5V / 1A / up to 250kbps / True RS-232 Transceiver with AutoShutdown Plus | Maxim Integrated |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |