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PDF MAX3212EAI Data sheet ( Hoja de datos )
| Número de pieza | MAX3212EAI | |
| Descripción | +2.7V to+3.6V-Powered / 1A Supply Current / 3-Driver/5-Receiver / True RS-232Transceiver | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-0312; Rev 0; 9/94
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
_______________General Description
The MAX3212 uses Maxim’s new proprietary Auto-
Shutdown mode to reduce supply current to 1µA. The
MAX3212, with 3 RS-232 drivers and 5 RS-232 receivers,
is intended for 2.7V to 3.6V-powered EIA/TIA-232E and
V.28/V.24 serial interface. True RS-232 levels are main-
tained across the operating range. A guaranteed data
rate of 235kbps provides compatibility with popular soft-
ware for communicating with personal computers.
Supply current is reduced to 1µA with Maxim’s new
AutoShutdown feature. When the MAX3212 does not
sense a valid signal level on the receiver inputs, the on-
board power supply and drivers shut down. This occurs
if the RS-232 cable is disconnected or if the transmit-
ters of the connected peripheral are turned off. The sys-
tem turns on again when a valid level is applied to any
RS-232 receiver input. As a result, the system saves
power without changes to the existing software.
A second power-management feature is incorporated to
permit automatic shutdown when the RS-232 connection
is valid but inactive. In this case, a transition detector
facilitates shutdown when the receivers are presented
with stationary RS-232 levels for long periods.
Three-state drivers are provided on receiver outputs so
that multiple receivers, generally of different interface
standards, can be wire-ORed at the UART. The
MAX3212 is available in 28-pin SO and SSOP packages.
________________________Applications
Notebook and Palmtop Computers
Peripherals
Instruments
Battery-Powered Equipment
______________Ordering Information
PART
MAX3212CWI
MAX3212CAI
MAX3212EWI
MAX3212EAI
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
28 Wide SO
28 SSOP
28 Wide SO
28 SSOP
Pin Configuration appears at end of data sheet.
* Patent pending
____________________________Features
BETTER THAN BIPOLAR!
o 1µA Supply Current Using AutoShutdown
o Operates from Single +2.7V to +3.6V Supply
o 28-Pin SSOP or Wide SO Packages
o Meets All EIA/TIA-232E & EIA/TIA-562 Specifications
o Mouse Driveability–Guaranteed
o Low-Cost, Surface-Mount External Components
o 235kbps Guaranteed Data Rate–
LapLink™ Compatible
o +5V Logic Compatible
o Complementary Receiver Output Always Active
o Flow-Through Pinout
__________Typical Operating Circuit
+3.0V
0.33µF
+3.0V
0.68µF 1N6050 15µH 1N6050
3 27 1
VCC V+ LN
26 FORCEON
2 16
LP V-
25 FORCEOFF
5 TRAN
6 INVALID
MAX3212
13 T1IN T1 T1OUT 19
14 T2IN
15 T3IN
8 R1OUT
T2 T2OUT 18
T3 T3OUT 17
R1 R1IN 24
5k
9 R2OUT
10 R3OUT
11 R4OUT
12 R5OUT
R2 R2IN 23
5k
R3 R3IN 22
5k
R4 R4IN 21
5k
R5 R5IN 20
+3.0V
7 R5OUTB
R5
EN GND
4 28
5k
AUTOSHUTDOWN OPERATION
FORCEOFF = HIGH, FORCEON = LOW
RS-232 Present
Yes
No
Status
On
Shut Down
0.33µF
________________________________________________________________ Maxim Integrated Products 1
Call toll free 1-800-998-8800 for free samples or literature.
1 page  
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
______________________________________________________________Pin Description
PIN NAME
FUNCTION
1 LN Inductor/Diode Connection Point
2 LP Inductor/Diode Connection Point
3 VCC Supply Voltage Input, 2.7V to 3.6V
Receiver Enable Control. Drive EN low to force receiver outputs into a high-Z state. Drive
4 EN EN high for normal operation. Cycle EN high then low to reset TRAN. TRAN is always low
when EN is high.
5
TRAN
Transition Detection Output. TRAN latches high when a transition occurs on any receiver
input while EN is low. Reset by cycling the EN pin high then low.
6
INVALID
Output of Invalid Signal Detector. Low if invalid RS-232 levels are present on all
receiver inputs, otherwise high.
7
R5OUTB
Complementary Output of R5OUT—always active
8–12
13, 14, 15
16
17, 18, 19
R1OUT–R5OUT
T1IN, T2IN, T3IN
V-
T3OUT, T2OUT, T1OUT
Receiver Outputs. Swing from GND to VCC. High-impedance when EN is low.
Transmitter Inputs
Negative Supply generated on-board
Transmitter Outputs
20–24
R5IN–R1IN
Receiver Inputs
25
FORCEOFF
Drive low to shut down transmitters and on-board power supply, overriding all automatic
circuitry and FORCEON (see Figure 3).
26
FORCEON
Drive high to overide automatic circuitry, keeping transmitters on (see Figure 3).
FORCEOFF = high.
27 V+ Positive Supply generated on-board
28
GND
Ground
_______________Detailed Description
The MAX3212 line driver/receiver is intended for 3V-
powered EIA/TIA-232E and V.28/V.24 communications
interfaces where 3 drivers and 5 receivers are required.
The operating voltage range extends from 3.6V down to
2.7V while still maintaining true RS-232 and EIA/TIA-562
transmitter output voltage levels.
under logic control. A complementary receiver remains
active in all cases, enabling a system incorporating the
MAX3212 to remain shut down and still monitor incom-
ing RS-232 activity.
Three-state drivers on all receiver outputs are provided
so that multiple receivers, generally of different inter-
face standards, can be wire-ORed at the UART.
The circuit comprises three sections: power supply,
transmitters, and receivers. The power-supply section
converts the supplied 3V to about ±6.5V, to provide
the voltages necessary for the drivers to meet true RS-
232 levels. External components are small and inex-
pensive.
The transmitters and receivers are guaranteed to oper-
ate at data rates of 235kbps.
The MAX3212 is equipped with Maxim’s new propri-
etary AutoShutdown circuitry. This achieves a supply
current of 1µA by shutting down the device when the
RS-232 cable is disconnected or when the connected
peripheral transmitters are turned off. While shut down,
all receivers can remain active or can be disabled
Switch-Mode Power Supply
The switch-mode power supply uses a single inductor
with two inexpensive diodes and two capacitors to
generate ±6.5V from the 2.7V to 3.6V input. The Typical
Operating Circuit shows the complete circuit for the pow-
er supply.
Use a 15µH inductor with a saturation current rating of at
least 350mA and under 1Ω resistance. Use 1N6050
diodes or equivalent. Surface-mount equivalents for the
1N6050 include the Motorola MMBD6050LT1, Philips
PMBD6050, and Allegro (formerly Sprague) TMPD6050LT.
For C1 and C2, use ceramic capacitors with values no
less than indicated in the Typical Operating Circuit.
These capacitors determine the ripple on V+ and V-, but
_______________________________________________________________________________________ 5
5 Page 
+2.7V to +3.6V-Powered, 1µA Supply Current,
3-Driver/5-Receiver, True RS-232 Transceiver
__________________Pin Configuration
TOP VIEW
LN 1
LP 2
VCC 3
EN 4
TRAN 5
INVALID 6
R5OUTB 7
R1OUT 8
R2OUT 9
R3OUT 10
R4OUT 11
R5OUT 12
T1IN 13
T2IN 14
MAX3212
28 GND
27 V+
26 FORCEON
25 FORCEOFF
24 R1IN
23 R2IN
22 R3IN
21 R4IN
20 R5IN
19 T1OUT
18 T2OUT
17 T3OUT
16 V-
15 T3IN
SO/SSOP
TRANSISTOR COUNT: 1435
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 12 Páginas | |
| PDF Descargar | [ Datasheet MAX3212EAI.PDF ] | |
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