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MAX3218
Technical data
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MAXIM MAX3218 Technical data

19-0380; Rev 0; 3/95
1µA Supply Current, 1.8V to 4.25V-Powered
RS-232 Transceiver with AutoShutdown™
_______________General Description
The MAX3218 RS-232 transceiver is intended for bat ­tery-powered EIA/TIA-232E and V.28/V.24 communica­tions interfaces that need two drivers and two receivers with minimum power consumption from a single low­voltage supply. It provides a wide +1.8V to +4.25V operating voltage range while maintaining true RS-232 and EIA/TIA-562 voltage levels. The MAX3218 runs from two alkaline, NiCd, or NiMH cells without any form of voltage regulator. A guaranteed 120kbps data rate provides compatibility with popular software for com ­municating with personal computers.
Supply current is reduced to 1 µA with Maxim’s new AutoShutdown™ feature. When the MAX3218 does not sense a valid signal level on the receiver inputs, the on­board power-supply and drivers shut down. This occurs if the RS-232 cable is disconnected or if the transmitters of the connected peripheral are turned off. The system turns on again when a valid level is applied to either RS-232 receiver input. As a result, the system saves power without changes to the existing software. Additionally, the MAX3218 can be forced into or out of shutdown, under logic control.
While shut down, all receivers can remain active or can be disabled under logic control, permitting a system incorporating the CMOS MAX3218 to monitor external devices while in low-power shutdown. Three-state dri ­vers are provided on both receiver outputs so that multi ­ple receivers, generally of different interface standards, can be on the same bus. The MAX3218 is available in 20-pin DIP and SSOP packages.
____________________________Features
BETTER THAN BIPOLAR!
♦ 1µA Supply Current Using AutoShutdown™ ♦ Operates Directly from Two Alkaline,
NiCd or NiMH Cells
♦ +1.8V to +4.25V Single-Supply Voltage Range ♦ 120kbps Data Rate Guaranteed ♦ Low-Cost Surface-Mount Components ♦ Meets EIA/TIA-232E Specifications ♦ Three-State Receiver Outputs ♦ Flow-Through Pinout ♦ On-Board DC-DC Converters ♦ 20-Pin SSOP and DIP Packages
______________Ordering Information
PART
MAX3218CPP
MAX3218CAP 0°C to +70°C
MAX3218C/D
MAX3218EPP -40°C to +85°C
MAX3218EAP -40°C to +85°C 20 SSOP
†
Contact factory for dice specifications.
TEMP. RANGE PIN-PACKAGE
0°C to +70°C
0°C to +70°C Dice
20 Plastic DIP
20 SSOP
†
20 Plastic DIP
MAX3218*
________________________Applications
__________________Pin Configuration
Battery-Powered Equipment
Subnotebook Computers
PDAs
Hand-Held Equipment
Peripherals
Cellular Phones
*
™ AutoShutdown is a trademark of Maxim Integrated Products.
________________________________________________________________
TOP VIEW
INVALID
FORCEON
FORCEOFF
GND
V T1IN T2IN
R1OUT R2OUT
LX
1 2 3 4
MAX3218
5 6
CC
7 8 9
10
DIP/SSOP
Call toll free 1-800-998-8800 for free samples or literature.
GND
20
V+
19
C1+
18
GND
17
C1-
16
V-
15
T1OUT
14
T2OUT
13
R1IN
12
R2IN
11
Maxim Integrated Products
1
1µA Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdown™
ABSOLUTE MAXIMUM RATINGS
Supply Voltages
....................................................................-0.3V to +4.6V
V
CC
V+ .......................................................... (V
V- .......................................................................+0.3V to -7.4V
to V-..........................................................................+12V
V
CC
LX ................................................................-0.3V to (1V + V+)
Input Voltages
T_IN, FORCEON, FORCEOFF
R_IN .................................................................................±25V
MAX3218
Output Voltages
T_OUT.............................................................................±15V)
R_OUT....................................................-0.3V to (V
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
............................ -0.3V to +7V
- 0.3V) to +7.5V
CC
CC
+ 0.3V)
ELECTRICAL CHARACTERISTICS
(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V
DC CHARACTERISTICS
Supply Current, Shutdown µA
Supply Current, AutoShutdown™ Disabled
LOGIC INPUTS AND RECEIVER OUTPUTS
Input Logic Threshold Low
Input Logic Threshold High
AUTOSHUTDOWN (FORCEON = GND, FORCEOFF = VCC)
Receiver Input Thresholds, Transmitters Enabled
Receiver Input Thresholds Transmitters Disabled
INVALID Output Low Voltage 0.4
INVALID Output High Voltage V
= 3.0V, TA= +25°C.)
CC
VCC= 3.0V, TA= +25°C, all R_IN open, FORCEON = GND, FORCEOFF = V
FORCEOFF = GND, TA= +25°C, VCC= 3.0V
FORCEON = FORCEOFF = VCC= 3.0V, no load mA2.0 3.0
T_IN, FORCEON, FORCEOFF
T_IN, FORCEON, FORCEOFF
T_IN, FORCEON = FORCEOFF = 0V or V
R_OUT, I
R_OUT, I
R_OUT, 0V ≤ R_OUT ≤ V
FORCEON = FORCEOFF = 0V
Figure 4a
1µA supply current, Figure 4a
I
OUT
I
OUT
CONDITIONS
= 1.0mA
OUT
= -0.4mA
OUT
CC
Positive threshold Negative threshold -2.8
= 1.0mA, -0.3V < R_IN < 0.3V
= -0.4mA, |R_IN|> 2.8V
Short-Circuit Duration, R_OUT, T_OUT to GND ....... Continuous
Continuous Power Dissipation (T
Plastic DIP (derate 11.11mW/°C above +70°C) ..........889mW
SSOP (derate 8.00mW/°C above +70°C) ..................640mW
Operating Temperature Ranges
MAX3218C_ P................................................... 0°C to +70°C
MAX3218E_ P ................................................. -40°C to +85°C
Storage Temperature Range ........................... -65°C to +150°C
Lead Temperature (soldering, 10sec) ........................... +300°C
CC
CC
CC
,
VCC- 0.25
MIN
A
to T
= +70°C)
, unless otherwise noted.
MAX
1.0 10
2.8
CC
UNITSMIN TYP MAXPARAMETER
V1.8 4.25Operating Voltage Range
µA1.0 10Supply Current, AutoShutdown™
V0.33 x V
V0.67 x V
µA0.001 ±1Input Leakage Current
V0.4Output Voltage Low
VVCC- 0.25 VCC- 0.08Output Voltage High
µA0.05 ±10Output Leakage Current
V
V-0.3 0.3
V
2 _______________________________________________________________________________________
1µA Supply Current, 1.8V to 4.25V-Powered
RS-232 Transceiver with AutoShutdown™
ELECTRICAL CHARACTERISTICS (continued)
(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V
EIA/TIA-232E RECEIVER INPUTS
Input Threshold Low
Input Threshold High
Input Hysteresis V
Input Resistance
EIA/TIA-232E TRANSMITTER OUTPUTS
Output Short-Circuit Current mA
= 3.0V, TA= +25°C.)
CC
VCC= 2.0V to 4.25V
VCC= 1.8V to 4.25V
VCC= 1.8V to 4.25V
V
CC
-15V < R_IN < 15V kΩ357
All transmitter outputs loaded with 3kΩ to groundOutput Voltage Swing V±5 ±6
VCC= 0V, -2V < T_OUT < 2V
CONDITIONS
0.4
0.3
= 1.8V to 3.6V
to T
MIN
MAX
0.7
±24 ±100
, unless otherwise noted.
UNITSMIN TYP MAXPARAMETER
3.0
2.8
TIMING CHARACTERISTICS
(Circuit of Figure 1, VCC= 1.8V to 4.25V, C1 = 0.47µF, C2 = C3 = C4 = 1µF, L1 = 15µH, TA= T Typical values are at V
= 3.0V, TA= +25°C.)
CC
MIN
to T
, unless otherwise noted.
MAX
MAX3218
V-25 +25Input Voltage Range
V
V
Ω300Output Resistance
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Output Enable Time
Transmitter Output Disable Time
Receiver Propagation Delay
Transmitter Propagation Delay
AUTOSHUTDOWN TIMING
Receiver Threshold to Transmitters Enabled
Receiver Positive or Negative Threshold to INVALID High
Receiver Positive or Negative Threshold to INVALID Low
ER
DR
ET
DT
PHLR
PLHR
PHLT
PLHT
WU
INVH
INVL
CONDITIONS
2500pF || 3kΩload each transmitter, one trans-
mitter switching, 150pF load each receiver
150pF load
150pF load
2500pF || 3kΩ load 2500pF || 3kΩ load
TA= +25°C, VCC= 3.0V, R CL= 50pF to 2500pF, measured from +3V to -3V or -3V to +3V
Figure 4b µs250t
Figure 4b µs1t
Figure 4b µs30t
= 3kΩ to 7kΩ,
L
UNITSMIN TYP MAXSYMBOLPARAMETER
kbps120 235Data Rate
ns90 300t
ns200 500t
µs250 450t
ns500t
290 1000t
260 1000t
1.9 2.7t
1.8 2.7t
ns
µs
V/µs3.0 30Transition Region Slew Rate
_______________________________________________________________________________________ 3
1µA Supply Current, 1.8V to 4.25V-Powered RS-232 Transceiver with AutoShutdown™
__________________________________________Typical Operating Characteristics
(Circuit of Figure 1, V
= 1.8V, all transmitter outputs loaded with 3kΩ, T
CC
= +25°C, unless otherwise noted.)
A
140
120
MAX3218
100
80
60
40
SUPPLY CURRENT (mA)
20
0
SUPPLY CURRENT vs.
SUPPLY VOLTAGE
1 TRANSMITTER FULL DATA RATE 1 TRANSMITTER 1/8 DATA RATE RL = 3kΩ + 2500pF
240kbps
120kbps
20kbps
0kbps
2.4 3.0
1.8 SUPPLY VOLTAGE (V)
3.6
4.2
2V/div
MAX3218-01
TIME TO EXIT SHUTDOWN
(ONE TRANSMITTER HIGH,
ONE TRANSMITTER LOW)
TRANSMITTING SUPPLY CURRENT
vs. LOAD CAPACITANCE
100
VCC = 2.4V
90 80
235kbps 70 60
120kbps 50
SUPPLY CURRENT (mA)
40
20kbps
30 20
1000
0
LOAD CAPACITANCE (pF)
FORCEON, FORCEOFF
V
OH
T_OUT
TRANSMITTER 1 OPERATING  AT SPECIFIED BIT RATE,  TRANSMITTER 2 OPERATING  AT 1/16 THAT RATE. 
3000
2000
4000
MAX3218-02
5000
V
1.8V
TRANSMITTER OUTPUT VOLTAGE vs. 
LOAD CAPACITANCE AT 120kbps
8 6 4 2
0
-2
-4
TRANSMITTER OUTPUT VOLTAGE (V)
-6
-8 1000
0
LOAD CAPACITANCE (pF)
2000
3000
V
V
OUT+
OUT-
4000
R
MAX3218-04
5000
CC =
= 3kΩ || 2500pF
L
100µs/div
V
OL
SLEW RATE vs.
TRANSMITTER CAPACITANCE
12
10
8
6
4
SLEW RATE (V/µs)
DATA RATE 120kbps, TRANSMITTERS LOADED WITH 
2
3kΩ PLUS INDICATED CAPACITANCE 
0
1000
0
+SLEW
-SLEW
2000
3000
LOAD CAPACITANCE (pF)
4 _______________________________________________________________________________________
4000
MAX3218-05
5000
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