19-1076; Rev 0; 9/96
±15kV ESD-Protected, EMC-Compliant, 230kbps
RS-232 Serial Port for Motherboards/Desktop PCs
_______________General Description
The MAX3185 is a complete DTE RS-232 serial port
designed to meet the stringent ESD requirements of the
European community. All transmitter outputs and receiv-
er inputs are protected to ±15kV using IEC 1000-4-2
Air-Gap Discharge, ±8kV using IEC 1000-4-2 Contact
Discharge, and ±15kV using the Human Body Model.
The MAX3185 has three RS-232 transmitters, five RS-
232 receivers, and no charge pump, optimizing it for
operation in desktop PC and motherboard applications.
It is guaranteed to run at data rates up to 230kbps, pro-
viding compatibility with popular software for communi-
cating with personal computers. Power-supply current
is less than 300µA for I
DD
and I
SS
, and less than 1mA
for I
CC
.
The MAX3185 is pin and functionally compatible with
the industry-standard 75185, so existing designs can
instantly become EMC compliant. The MAX3185 is
available in an SO package and in the tiny SSOP that
further reduces board space.
____________________________Features
o
Enhanced ESD Protection:
±15kV—Human Body Model
±8kV—IEC1000-4-2, Contact Discharge
±15kV—IEC1000-4-2, Air-Gap Discharge
o
Latchup Free During an ESD Event
o
20-Pin SSOP and SO Packages
o
Guaranteed 230kbps Data Rate
o
Flow-Through Pinout
o
Pin Compatible with SN75C185
o
Complete DTE Serial Port
MAX3185
______________Ordering Information
PART
TEMP. RANGE
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 SO
20 SSOP
20 SO
20 SSOP
MAX3185CWP
MAX3185CAP
MAX3185EWP
MAX3185EAP
________________________Applications
Desktop PC
Motherboards
Instruments
Equipment Meeting IEC1000-4-2
__________Typical Operating Circuit
MAX3186
T1
T2
TTL/CMOS
LOGIC
I/O
RS-232
T3
INTERCONNECTING
T4
CABLE
T5
R1
R2
R3
R5
T1
R4
R3
__________________Pin Configuration
TOP VIEW
V
DD
1
R1IN 2
20 V
CC
19 R1OUT
18 R2OUT
17 R3OUT
16 T1IN
15 T2IN
14 R4OUT
13 T3IN
12 R5OUT
MAX3185
R1
R2
TTL/CMOS
LOGIC
I/O
R2IN 3
R3IN 4
T1OUT 5
T2OUT 6
R4IN 7
T3OUT 8
R5IN 9
T2
T3
V
SS
10
MAX3185
SO/SSOP
11 GND
________________________________________________________________
Maxim Integrated Products
1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
±15kV ESD-Protected, EMC-Compliant, 230kbps
RS-232 Serial Port for Motherboards/Desktop PCs
MAX3185
ABSOLUTE MAXIMUM RATINGS
V
CC
...........................................................................-0.3V to +7V
V
DD
.........................................................................-0.3V to +14V
V
SS
......................................................................... +0.3V to -14V
Input Voltages
T
IN
........................................................................-0.3V to +6V
R
IN
...................................................................................±30V
Output Voltages
T
OUT
.................................................................................±15V
R
OUT
.......................................................-0.3V to (V
CC
+ 0.3V)
Short-Circuit Duration
T
OUT
(one at a time)...............................................Continuous
R
OUT
(one at a time) ..............................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
Wide SO (derate 10.00mW/°C above +70°C)..............800mW
SSOP (derate 8.00mW/°C above +70°C) ....................640mW
Operating Temperature Ranges
MAX3185C_ P .....................................................0°C to +70°C
MAX3185E_ P ..................................................-40°C to +85°C
Storage Temperature Range ............................-65°C to +160°C
Lead Temperature (soldering, 10sec) ............................+300°C
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.
ELECTRICAL CHARACTERISTICS
(V
CC
= +4.5V to +5.5V, V
DD
= +10.8V to +13.2V, V
SS
= -10.8V to -13.2V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values
are at T
A
= +25°C.)
PARAMETER
DC CHARACTERISTICS
V
CC
Operating Voltage Range
V
DD
V
SS
I
CC
Supply Current
LOGIC
Input Logic Threshold Low
Input Logic Threshold High
Input Leakage Current
Output Voltage Low
Output Voltage High
TRANSMITTER OUTPUTS
Output Voltage Swing
Transmitter Output Resistance
RS-232 Output Short-Circuit
Current
RECEIVER INPUTS
Receiver Input Voltage
Operating Range
RS-232 Input Threshold Low
RS-232 Input Threshold High
RS-232 Input Hysteresis
RS-232 Input Resistance
Receiver Output Short-Circuit
Current
2
3
0.65
5
±10
7
-25
0.75
2.4
25
V
V
V
V
kΩ
mA
V
DD
= 7.0V, V
SS
= -7.0V, R
L
= 3kΩ
V
DD
= 12V, V
SS
= -12V, R
L
= 3kΩ
V
CC
= V
DD
= V
SS
= 0V, V
T_OUT
= ±2V
±5.0
±9.5
300
±35
±60
V
Ω
mA
V
OLR
V
OHR
R
OUT
; I
SINK
= 3.2mA
R
OUT
; I
SOURCE
= 1mA
V
CC
- 0.6
V
ILT
V
IHT
T
IN
T
IN
2.0
0.01
1
0.4
0.8
V
V
µA
V
V
I
DD
I
SS
No load
No load
No load
4.5
10.8
-13.2
380
185
185
5.5
13.2
-10.8
1500
500
500
µA
V
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
_______________________________________________________________________________________
±15kV ESD-Protected, EMC-Compliant, 230kbps
RS-232 Serial Port for Motherboards/Desktop PCs
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +4.5V to +5.5V, V
DD
= +10.8V to +13.2V, V
SS
= -10.8V to -13.2V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values
are at T
A
= +25°C.)
PARAMETER
ESD CHARACTERISTICS
Human Body Model
ESD Protection
TIMING CHARACTERISTICS
Transmitter Output
Propagation Delay, Low to High
Transmitter Output
Propagation Delay, High to Low
Transmitter Propagation Delay
Skew,
|
t
PLHT
- t
PHLT
|
t
PLHT
t
PHLT
t
SKT
V
DD
= 12V, V
SS
= -12V, R
L
= 3kΩ,
C
L
= 1000pF, T
A
= +25°C
V
DD
= 12V, V
SS
= -12V, R
L
= 3kΩ,
C
L
= 1000pF, T
A
= +25°C
V
DD
= 12V, V
SS
= -12V, R
L
= 3kΩ,
C
L
= 1000pF, T
A
= +25°C
V
DD
= 12V, V
SS
= -12V,
R
L
= 3kΩ to 7kΩ,
measured from +3V to -3V
or -3V to +3V, Figure 3,
T
A
= +25°C
C
L
= 150pF to
2500pF
C
L
= 50pF to
1000pF
4
8
4
4
0.4
30
V/µs
30
4.0
4.0
0.4
120
kbps
C
L
= 50pF to
1000pF
230
±7.5
V
µs
µs
µs
µs
µs
µs
IEC1000-4-2 (Contact Discharge)
IEC1000-4-2 (Air-Gap Discharge)
±15
±8
±15
kV
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX3185
Transition Output Slew Rate
SR
Receiver Output
Propagation Delay, Low to High
Receiver Output
Propagation Delay, High to Low
Receiver Propagation Delay
Skew,
|
t
PLHR
- t
PHLR
|
t
PLHR
t
PHLR
t
SKR
V
CC
= 5V, C
L
= 50pF, T
A
= +25°C
V
CC
= 5V, C
L
= 50pF, T
A
= +25°C
V
CC
= 5V, C
L
= 50pF, T
A
= +25°C
V
CC
= 5V, V
DD
= 12V,
V
SS
= -12V,
R
L
= 3kΩ to 7kΩ,
T
A
= +25°C
C
L
= 50pF to
2500pF
Guaranteed Data Rate
DR
Mouse Driveability
T3OUT = -5mA, T1OUT = T2OUT = +5mA
_______________________________________________________________________________________
3
±15kV ESD-Protected, EMC-Compliant, 230kbps
RS-232 Serial Port for Motherboards/Desktop PCs
MAX3185
__________________________________________Typical Operating Characteristics
(V
CC
= +5.0V, V
DD
= +12.0V, V
SS
= -12.0V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX3185-TOC01
SUPPLY CURRENT
vs. LOAD CAPACITANCE
MAX3185-TOC02
SLEW RATE
vs. LOAD CAPACITANCE
14
12
SLEW RATE (V/µs)
FALL
10
8
6
4
2
0
1 TRANSMITTER 240kbps
2 TRANSMITTERS 15kbps
3kΩ + C
L
LOAD
MAX3185-TOC03
20
15
I
DD
, 240kbps
I
DD
, 120kbps
25
20
15
SUPPLY CUREENT (mA)
10
5
0
-5
-10
-15
-20
-25
I
CC
I
DD
, 240kbps
I
DD
, 120kbps
I
DD
, 20kbps
1 TRANSMITTER AT DATA RATE
16
SUPPLY CUREENT (mA)
10
I
DD
, 20kbps
1 TRANSMITTER AT DATA RATE
5
I
CC
2 TRANSMITTERS AT DATA RATE / 16
3kΩ + 2500pF LOAD
I
SS
, 120kbps
I
SS
, 240kbps
0
-5
-10
-15
-20
10.8
I
SS
, 20kbps
I
SS
,
20kbps 2 TRANSMITTERS AT DATA RATE / 16
I
SS
, 120kbps
I
SS
, 240kbps
3kΩ + C
L
LOAD
RISE
11.4
12.0
12.6
13.2
0
SUPPLY VOLTAGE (V)
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
5000
0
1000
2000
3000
4000
5000
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
MAX3185-TOC04
MAX3185 TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CURRENT PER TRANSMITTER
TRANSMITTER OUTPUT VOLTAGE (V)
MAX3185-TOC05
SLEW RATE
vs. TEMPERATURE
MAX3185-TOC06
12.5
TRANSMITTER OUTPUT VOLTAGE (V)
10.0
7.5
5.0
2.5
0
-2.5
-5.0
-7.5
120kbps
240kbps
1 TRANSMITTER AT DATA RATE
2 TRANSMITTERS AT DATA RATE / 16
3kΩ + C
L
LOAD
15
10
VOUT+
5
T1
25
20
SLEW RATE (V/µs)
FALL, 500pF
RISE, 500pF
10
RISE, 2000pF
5
0
FALL, 2000pF
15
0
-5
-10
-15
V
CC
V
OUT+
T2
VOUT-
T3
240kbps
120kbps
V
OUT-
-10.0
-12.5
0
1000
2000
3000
4000
LOAD CAPACITANCE (pF)
5000
0
2
4
6
8
10
12
14
16
18
-55 -35 -15
5
25 45
65 85 105 125
LOAD CURRENT PER TRANSMITTER (mA)
TEMPERATURE (°C)
4
_______________________________________________________________________________________
±15kV ESD-Protected, EMC-Compliant, 230kbps
RS-232 Serial Port for Motherboards/Desktop PCs
______________________________________________________________Pin Description
PIN
1
12, 14, 17, 18, 19
16, 15, 13
10
11
2, 3, 4, 7, 9
5, 6, 8
20
NAME
V
DD
R5OUT–R1OUT
T3IN, T2IN, T1IN
V
SS
GND
R1IN–R5IN
T1OUT, T2OUT, T3OUT
V
CC
FUNCTION
Supply-Voltage Input, +10.8V to +13.2V
Receiver Outputs, swing between GND and V
CC
Transmitter Inputs
Supply-Voltage Input, -10.8V to -13.2V
Ground. Connect system to ground.
Receiver Inputs
Transmitter Outputs, swing between V
DD
and V
SS
Supply-Voltage Input, +4.5V to +5.5V
MAX3185
_______________Detailed Description
R
C
50M to 100M
CHARGE-CURRENT
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
R
D
330Ω
DISCHARGE
RESISTANCE
DEVICE
UNDER
TEST
±15kV ESD Protection
As with all Maxim devices, ESD-protection structures
are incorporated on all pins to protect against electro-
static discharges encountered during handling and
assembly. The MAX3185 driver outputs and receiver
inputs have extra protection against static electricity
found in normal operation. Maxim’s engineers devel-
oped state-of-the-art structures to protect these pins
against ESD of ±15kV, without damage. After an ESD
event, the MAX3185 continues working without latchup.
ESD protection can be tested in several ways. The
transmitter outputs and the receiver inputs are charac-
terized for protection to the following:
1) ±15kV using the Human Body Model
2) ±8kV using the Contact-Discharge Method specified
in IEC1000-4-2 (formerly IEC801-2)
3) ±15kV using the Air-Gap Method specified in
IEC1000-4-2 (formerly IEC801-2)
Cs
150pF
STORAGE
CAPACITOR
Figure 1a. IEC1000-4-2 ESD Test Model
I
100%
90%
I
PEAK
ESD Test Conditions
ESD performance depends on a number of conditions.
Contact Maxim for a reliability report that documents
test setup, methodology, and results.
10%
t
r
= 0.7ns to 1ns
30ns
60ns
t
Figure 1b. IEC1000-4-2 ESD-Generator Current Waveform
_______________________________________________________________________________________
5
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