19-1632; Rev 1; 6/01
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
General Description
The MAX3238E/MAX3248E transceivers use Maxim’s
revolutionary AutoShutdown Plus™ feature to achieve
10nA supply current. These devices shut down the on-
board power supply and drivers when they do not sense
a valid signal transition on either the receiver or transmit-
ter inputs. This occurs if the RS-232 cable is disconnect-
ed or if the transmitters of the connected peripheral are
turned off. The devices turn on again when a valid transi-
tion is applied to any RS-232 receiver or transmitter input.
AutoShutdown Plus automatically achieves this power
savings through its on-board circuitry, as no changes are
required to the existing BIOS or operating system.
All RS-232 inputs and outputs, as well as the logic I/O
pins, have enhanced ESD protection to ±15kV. The addi-
tional ESD protection on the logic I/O pins makes the
MAX3238E/MAX3248E ideal for cell phone data cable
applications because it eliminates the need for costly
external TransZorb™ or protection schemes.
The MAX3238E/MAX3248E contain five drivers and three
receivers and are 3V-powered EIA/TIA-232 and V.28/V.24
communication interfaces intended for cell phones, data
cables, and modem applications. A proprietary, high-effi-
ciency, 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 popular software for communicating with personal
computers.
The MAX3238E and the MAX3248E differ only in their
input logic thresholds. The MAX3238E has standard logic
thresholds, while the MAX3248E has low-level logic
thresholds of 0.6V to 1.2V, which are ideal for 1.8V sys-
tems.
The transmitter inputs, FORCEON, and
FORCEOFF
have
a 400kΩ active positive feedback resistor. Once driven to
a valid logic level, they will retain this level if the driving
signal is removed or goes high impedance. Unused
transmitter and logic inputs may be left unconnected. The
MAX3238E/MAX3248E can operate with supply voltages
ranging from +3.0V to +5.5V.
Features
o
Enhanced ESD Protection on RS-232 I/O Pins and
All Logic Pins
±15kV—Human Body Model
±8kV—IEC 1000-4-2 Contact Discharge
±15kV—IEC 1000-4-2 Air-Gap Discharge
o
Guaranteed Data Rate: 250kbps
o
10nA Low-Power Shutdown with Receivers Active
o
Schmitt Triggers on All Inputs
o
Flow-Through Pinout
o
Meets EIA/TIA-232 Specifications Down to 3.0V
o
Guaranteed 6V/µs Slew Rate
o
Low-Level Logic Thresholds (MAX3248E)
o
RS-232-Compatible Outputs to 2.7V
MAX3238E/MAX3248E
Ordering Information
PART
MAX3238ECAI
MAX3238EEAI
MAX3248ECAI
MAX3248EEAI
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
28 SSOP
28 SSOP
28 SSOP
28 SSOP
Typical Operating Circuit appears at end of data sheet.
___________________Pin Configuration
TOP VIEW
C2+
GND
C2-
V-
T1OUT
T2OUT
T3OUT
1
2
3
4
5
6
7
8
9
28 C1+
27 V+
26 V
CC
25 C1-
24 T1IN
MAX3238E
MAX3248E
23 T2IN
22 T3IN
21 R1OUT
20 R2OUT
19 T4IN
18 R3OUT
17 T5IN
16 R1OUTB
15 INVALID
Applications
Cellular Data Cables
Modems
Battery-Powered Equipment
Peripherals
Data Cradles
Printers
R1IN
R2IN
T4OUT 10
R3IN 11
T5OUT 12
FORCEON 13
FORCEOFF 14
AutoShutdown Plus is a trademark of Maxim Integrated Products.
TransZorb is a trademark of General Semiconductor Industries, Inc.
†
C4;
4,r
pg.
SSOP
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
MAX3238E/MAX3248E
ABSOLUTE MAXIMUM RATINGS
V
CC
...........................................................................-0.3V to +6V
V+ (Note 1) ...............................................................-0.3V to +7V
V- (Note 1) ................................................................+0.3V to -7V
V+ + |V-| (Note 1) .................................................................+13V
Input Voltages
T_IN,
FORCEOFF,
FORCEON ..............................-0.3V to +6V
R_IN .................................................................................±25V
Output Voltages
T_OUT...........................................................................±13.2V
R_OUT,
INVALID
....................................-0.3V to (V
CC
+ 0.3V)
Short-Circuit Duration
T_OUT (one at a time) ............................................Continuous
Continuous Power Dissipation (T
A
= +70°C)
28-Pin SSOP (derate 9.52mW/°C above +70°C) .........762mW
Operating Temperature Ranges
MAX3238ECAI/MAX3248ECAI ...........................0°C to +70°C
MAX3238EEAI/MAX3248EEAI .........................-40°C to +85°C
Storage Temperature Range ............................-65°C to +150°C
Lead Temperature (soldering, 10s) ................................+300°C
Note 1:
V+ and V- can have a maximum magnitude of +7V, but their absolute difference can not exceed +13V.
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
= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
CONDITIONS
Receivers idle, T_IN = V
CC
or GND, FORCEON =
GND,
FORCEOFF
= V
CC
R_IN = FORCEON = GND,
FORCEOFF
= V
CC,
T_IN = V
CC
or GND
FORCEOFF
= GND, R_IN = GND, T_IN = V
CC
or GND
FORCEON =
FORCEOFF
= V
CC
, no load
MIN
TYP
MAX
UNITS
DC CHARACTERISTICS
(V
CC
= +3.3V or +5.0V, T
A
= +25°C)
0.75
10
10
0.5
6
300
300
2.0
µA
nA
nA
mA
Supply Current, AutoShutdown Plus
Supply Current, Shutdown
Supply Current, AutoShutdown Plus
Disabled
LOGIC INPUTS AND RECEIVER OUTPUTS
T_IN (active)
MAX3238E
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 3.3V
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 5.0V
T_IN (active)
MAX3248E
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 3.3V
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 5.0V
T_IN (active)
MAX3238E
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 3.3V
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 5.0V
T_IN (active)
MAX3248E
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 3.3V
FORCEON,
FORCEOFF,
and T_IN
wake-up threshold; V
CC
= 5.0V
2
0.8
0.8
0.8
0.6
0.6
0.6
1.20
1.00
1.45
0.7
0.85
1.0
1.60
1.30
2.10
1.10
0.95
1.15
2.0
2.0
2.4
1.2
1.2
1.6
V
V
Input Logic Threshold Low
Input Logic Threshold High
_______________________________________________________________________________________
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Leakage Current
Output Leakage Current
Output Voltage Low
Output Voltage High
RECEIVER INPUTS
Input Voltage Range
Input Threshold Low
Input Threshold High
Input Hysteresis
Input Resistance
T
A
= +25°C
Positive threshold
Negative threshold
-2.7
-0.3
0.3
0.4
V
CC -
0.6
0.3
60
25
15
30
60
3
AutoShutdown
(FORCEON = GND,
FORCEOFF
= V
CC
)
Receiver Input Threshold to
INVALID
Output High
Receiver Input Threshold to
INVALID
Output Low
INVALID
Output Voltage Low
INVALID
Output Voltage High
Receiver Positive or Negative
Threshold to
INVALID
High (t
INVH
)
Receiver Positive or Negative
Threshold to
INVALID
Low (t
INVL
)
Receiver or Transmitter Edge to
Transmitters Enabled (t
WU
)
Receiver or Transmitter Edge to
Shutdown (t
AUTOSHDN
)
TRANSMITTER OUTPUTS
Output Voltage Swing
Output Resistance
Output Short-Circuit Current
ESD PROTECTION
ESD Protection (R_IN, T_IN, R_OUT,
T_OUT, FORCEON,
FORCEOFF,
INVALID,
R_OUTB)
IEC 1000-4-2 Air-Gap Discharge Method
IEC 1000-4-2 Contact Discharge Method
Human Body Model
±15
±8
±15
kV
All transmitter outputs loaded with 3kΩ to ground
V
CC
= 0, T
OUT
= ±2V
V
CC
≤
3.6V
V
CC
> 3.6V
±5.0
300
±5.4
50k
±35
±40
±60
±100
V
Ω
mA
Figure 4a
Figure 4a
I
OUT
= 1.0mA
I
OUT
= -1.0mA
V
CC
= 5V, Figure 4b
V
CC
= 5V, Figure 4b
V
CC
= 5V, Figure 4b (Note 3)
Figure 4b
2.7
V
V
V
V
µs
µs
µs
s
V
CC
= 3.3V
V
CC
= 5.0V
V
CC
= 3.3V
V
CC
= 5.0V
-25
0.6
0.8
1.0
1.4
1.5
2.0
0.6
5
7
2.4
2.4
25
V
V
V
V
kΩ
CONDITIONS
T_IN, FORCEON,
FORCEOFF
(Note 2)
Receivers disabled
I
OUT
= 1.0mA
I
OUT
= -1.0mA
V
CC
-
0.6
V
CC
-
0.1
MIN
TYP
9
±0.05
MAX
18
±10
0.4
UNITS
µA
µA
V
V
MAX3238E/MAX3248E
_______________________________________________________________________________________
3
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
MAX3238E/MAX3248E
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +3.0V to +5.5V, C1–C4 = 0.1µF (tested at 3.3V ±5%), C1–C4 = 0.22µF (tested at 3.3V ±10%), C1 = 0.047µF, and
C2–C4 = 0.33µF (tested at 5.0V ±10%), T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
TIMING CHARACTERISTICS
Maximum Data Rate
Receiver Propagation Delay
Receiver Output Enable Time
Receiver Output Disable Time
Transmitter Skew
Receiver Skew
R
L
= 3kΩ, C
L
= 1000pF, one transmitter switching
R_IN to R_OUT,
C
L
= 150pF
Normal operation
Normal operation
| t
PHL
- t
PLH
|
| t
PHL
- t
PLH
|
V
CC
= 3.3V,
T
A
= +25°C,
R
L
= 3kΩ to 7kΩ,
measured from +3V to
-3V or -3V to +3V
C
L
= 150pF to 1000pF
C
L
= 150pF to 2500pF
6
t
PHL
t
PLH
250
0.15
0.15
2.6
2.4
50
50
30
V/µs
4
30
kbps
µs
µs
µs
ns
ns
CONDITIONS
MIN
TYP
MAX
UNITS
Transition-Region Slew Rate
Note 2:
The transmitter inputs have an active positive feedback resistor. The input current goes to zero when the inputs are at the
supply rails.
Note 3:
During AutoShutdown only, a transmitter/receiver edge is defined as a transition through the transmitter/receiver input logic
wake-up thresholds.
__________________________________________Typical Operating Characteristics
(V
CC
= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, T
A
= +25°C, unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
0
MAX3238E toc01
SLEW RATE vs. LOAD CAPACITANCE
MAX3238E toc02
SUPPLY CURRENT vs. LOAD CAPACITANCE
WHEN TRANSMITTING DATA
250kbps
40
SUPPLY CURRENT (mA)
120kbps
MAX3238 TOC-03
12
10
SLEW RATE (V/µs)
8
SR+
6
4
2
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C
L
0
500
1000
1500
2000
2500
50
TRANSMITTER OUTPUT VOLTAGE (V)
V
OUT
+
SR-
FOR DATA RATES UP TO 250kbps
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C
L
30
20kbps
20
1 TRANSMITTER 20kbps, 120 kbps, 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ + C
L
10
V
OUT-
0
500
1000
1500
2000
2500
3000
0
3000
0
500
LOAD CAPACITANCE (pF)
1000 1500 2000 2500
LOAD CAPACITANCE (pF)
3000
LOAD CAPACITANCE (pF)
4
_______________________________________________________________________________________
+3.0V to +5.5V, 10nA, 250kbps RS-232 Transceivers
with ±15kV ESD-Protected I/O and Logic Pins
MAX3238E/MAX3248E
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, 250kbps data rate, 0.1µF capacitors, all transmitters loaded with 3kΩ, T
A
= +25°C, unless otherwise noted.)
TRANSMITTER OUTPUT VOLTAGE
vs. SUPPLY VOLTAGE
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
2.0
TRANSMITTER OUTPUT VOLTAGE (V)
V
OUT
+
MAX3238E toc04
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX3238E toc05
50
40
SUPPLY CURRENT (mA)
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ +1000pF
30
20
1 TRANSMITTER 250kbps
4 TRANSMITTERS 15.6kbps
ALL TRANSMITTERS LOADED
WITH 3kΩ +1000pF
2.0
2.5
3.0
3.5
4.0
4.5
5.0
10
V
OUT-
0
2.5
3.0
3.5
4.0
4.5
5.0
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
______________________________________________________________Pin Description
PIN
NAME
C2+
GND
C2-
V-
T_OUT
R_IN
FUNCTION
Positive Terminal of Inverting Charge-Pump Capacitor
Ground
Negative Terminal of Inverting Charge-Pump Capacitor
-5.5V Generated by the Charge Pump
RS-232 Transmitter Outputs (T1OUT–T5OUT)
RS-232 Receiver Inputs (R1IN–R3IN)
Force-On Input. Drive high to override AutoShutdown Plus, keeping transmitters and
receivers on (FORCEOFF must be high) (Table 1). This pin has an active positive feedback
resistor. Once driven to a valid logic level, the pin retains that level if left unconnected until
power is cycled.
Force-Off Input. Drive low to shut down transmitters, receivers (except R1OUTB), and on-
board supply. This overrides AutoShutdown Plus and FORCEON (Table 1). This pin has an
active positive feedback resistor. Once driven to a valid logic level, the pin retains that
level if left unconnected until power is cycled.
Output of the Valid Signal Detector. A logic 1 indicates if a valid RS-232 level is present on
receiver inputs.
Noninverting Complementary Receiver Output. Always active.
TTL/CMOS Transmitter Inputs (T5IN–T1IN). This pin has an active positive feedback resis-
tor. Once driven to a valid logic level, the pin retains that level if left unconnected until
power is cycled.
TTL/CMOS Receiver Outputs (R3OUT–R1OUT)
Negative Terminal of Voltage-Doubler Charge-Pump Capacitor
+3.0V to +5.5V Supply Voltage
+5.5V Generated by the Charge Pump
Positive Terminal of Voltage-Doubler Charge-Pump Capacitor
5
1
2
3
4
5, 6, 7, 10, 12
8, 9, 11
13
FORCEON
14
FORCEOFF
15
16
17, 19, 22, 23, 24
18, 20, 21
25
26
27
28
INVALID
R1OUTB
T_IN
R_OUT
C1-
V
CC
V+
C1+
_______________________________________________________________________________________
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