19-0144; Rev. 0; 9/93
_______________General Description
The MAX562 is designed specifically for notebook and
palmtop computers that need to transfer data quickly.
It runs at data rates up to 230kbps, and has a guaranteed 4V/µs slew rate. This device meets the new
EIA/TIA-562 standard that guarantees compatibility with
RS-232 interfaces.
The MAX562 has low-power shutdown and keep-awake
modes. In keep-awake mode, the transmitters are disabled but all receivers are active, allowing unidirectional communication. In shutdown mode, the entire chip is
disabled and all outputs are in a high-impedance state.
The MAX562 is available in a standard 28-pin SO package, and in a smaller footprint shrink small-outline
package (SSOP).
________________________Applications
Palmtop, Notebook, and Subnotebook
Computers
Peripherals
Battery-Powered Equipment
____________________________Features
♦ 230kbps Data Rate, LapLink™ Compatible
♦ Operates from a 2.7V to 5.25V Supply
♦ Designed for EIA/TIA-562 and EIA/TIA-232 Applications
♦ Guaranteed 4.0V/µs Slew Rate
♦ 3 Drivers, 5 Receivers
♦ Flow Through Pinout
♦ Low-Power Shutdown and Keep-Awake Modes
♦ Low-Cost, Surface-Mount External Capacitors
______________Ordering Information
* Contact factory for dice specifications.
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
________________________________________________________________
Maxim Integrated Products
1
28
27
26
25
24
23
22
21
20
19
18
17
16
15
1
2
3
4
5
6
7
8
9
10
11
12
13
14
V
CC
GND
VC2+
C2R1
IN
SHDN
R2
IN
R3
IN
R4
IN
R5
IN
T1
OUT
T2
OUT
T3
OUT
EN
T3
IN
T2
IN
T1
IN
R5
OUT
R4
OUT
R3
OUT
R2
OUT
R1
OUT
C1A-
C1B-
C1B+
C1A+
V+
MAX562
SO/SSOP
TOP VIEW
__________________Pin Configuration
T1
T2
T3
R1
R2
R3
R4
R5
5k
5k
5k
5k
5k
GND
19
SHDN
R5
IN
R4
IN
R3
IN
R2
IN
R1
IN
T3
OUT
T2
OUT
T1
OUT
R5
OUT
R4
OUT
R3
OUT
R2
OUT
R1
OUT
EN
T3
IN
T2
IN
T1
IN
VOLTAGE
DOUBLER/TRIPLER
VOLTAGE
INVERTER
20
21
22
23
16
17
18
26
28
453
2
1
25
12
24
11
13
6
7
8
9
10
14
27
15
C2-
C2+
V-
C1A C1B
C1A+ C1A- C1B+ C1B-
V
CC
V+
C3 0.68µF
C4 0.33µF
0.33µF
+2.7V TO
+5.25V
INPUT
0.33µF
0.33µF 0.33µF
CMOS
INPUTS
CMOS
OUTPUTS
EIA/TIA
-562
INPUTS
EIA/TIA
-562
OUTPUTS
C2
MAX562
__________Typical Operating Circuit
Call toll free 1-800-998-8800 for free samples or literature.
PART TEMP. RANGE PIN-PACKAGE
MAX562CWI 0°C to +70°C 28 SO
MAX562CAI 0°C to +70°C 28 SSOP
MAX562C/D 0°C to +70°C Dice*
MAX562EWI -40°C to +85°C 28 SO
MAX562EAI -40°C to +85°C 28 SSOP
™ LapLink is a registered trademark of Traveling Software, Inc.
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
VCC......................................................................... -0.3V to +6V
V+ ................................................................ (V
CC
- 0.3V) to +6V
V-............................................................................ +0.3V to -6V
C1A+, C1B+.................................................. -6V to (V+ + 0.3V)
C1A-, C1B-, C2+........................................ -0.3V to (V+ + 0.3V)
C2-.................................................................. (V- - 0.3V) to +6V
Input Voltages
T
IN
, EN,
SHDN
........................................ -0.3V to (VCC+ 0.3V)
R
IN
....................................................................................±25V
Output Voltages
T
OUT
............................................................................... ±15V
R
OUT
...................................................... -0.3V to (VCC+ 0.3V)
Short-Circuit Duration
T
OUT
to GND........................................................ Continuous
R
OUT
to GND, VCC................................................ Continuous
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 12.50mW/°C above +70°C).................. 1000mW
SSOP (derate 9.52mW/°C above +70°C) ................. 762mW
Operating Temperature Ranges:
MAX562C_ _ ..................................................... 0°C to +70°C
MAX562E_ _ .................................................. -40°C to +85°C
Storage Temperature Range........................... -65°C to +160°C
Lead Temperature (soldering, 10sec)........................... +300°C
ELECTRICAL CHARACTERISTICS
(VCC= 2.7V to 5.25V, C1A = C1B = C2 = C4 = 0.33µF, C3 = 0.68µF, TA= T
MIN
to T
MAX
, unless otherwise noted.)
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.
PARAMETER MIN TYP MAX UNITS
Input Voltage Operating Range ±25 V
Input Threshold Low 0.8 V
Input Threshold High 2.4 V
Input Hysteresis
No hysteresis when
SHDN
= 0V
0.3 V
Input Resistance -15V < VIN< 15V 3 5 7 kΩ
Output Voltage Swing All transmitter outputs loaded with 3kΩ to GND ±3.7 ±4.5 ±6.0 V
VCC= 2.7V to 3.6V 0.6
Input Logic Threshold Low
TIN, EN,
SHDN
VCC= 5.0V +5%, -10% 0.8
V
VCC= 2.7V to 3.6V 1.8
Input Logic Threshold High
TIN, EN,
SHDN
VCC= 5.0V +5%, -10% 3.0
V
Output Voltage Low I
OUT
= 1.6mA 0.4 V
Output Voltage High I
OUT
= -1.0mA V
Output Leakage Current
EN = GND, 0V ≤ R
OUT
≤ V
CC
0.05 ±10 µA
Operating Supply Voltage 2.7 5.25 V
No load 20 33
VCCPower-Supply Current VCC= 3.3V
All outputs loaded 3kΩ 24
mA
EN = VCC,
SHDN
= GND, TA= +25°C
45 130 µA
Shutdown Supply Current
SHDN
= EN = GND, TA= +25°C
1 50 µA
Output Leakage Current ±10 µA
Output Resistance VCC= V+ = V- = 0V, V
OUT
= ±2V 300 Ω
Output Short-Circuit Current V
OUT
= 0V ±60 mA
Shutdown Supply Current with
Receivers Active
VCC-0.5
CONDITIONS
EIA/TIA-562 TRANSMITTERS
EIA/TIA-562 RECEIVERS
POWER SUPPLY
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
_______________________________________________________________________________________ 3
AC CHARACTERISTICS
PARAMETER CONDITIONS MIN TYP MAX UNITS
Receiver Propagation Delay,
Normal Operation
250 500
ns
CL= 150pF,
SHDN
= GND
Figure 2
3000 4000
Receiver Propagation Delay,
Keep-Awake Mode
2000 3000
ns
Receiver-Output Enable Time Figure 4 100 250 ns
Receiver-Output Disable Time Figure 4 250 500 ns
Data Rate
1000pF || 3kΩ load each transmitter output,
150pF load each receiver output
230.4 280.0 kbits/sec
Transmitter Slew Rate
CL= 50pF to 2500pF,
RL= 3kΩ to 7kΩ. Measured from +3V to -3V, or
-3V to +3V
4 6 30 V/µs
CL= 2500pF 0.22 3.1
Transmitter Rise/Fall Time
RL= 3kΩ measured
from +3.3V to -3.3V
or -3.3V to +3.3V
CL= 1000pF 0.22 2.1
µs
t
PHLT
900 1700
Transmitter Propagation Delay
2500pF || 3kΩ load,
Figure 1
t
PLHT
1000 1700
ns
Transmitter-Output Enable Time 100 µs
Transmitter-Output Disable Time Figure 3 600 ns
CL= 150pF,
SHDN
= VCCFigure 2
t
PHLR
100 250
t
ET
t
DT
t
PLHR
t
PHLS
t
PLHS
t
ER
t
DR
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
4
_______________________________________________________________________________________
__________________________________________Typical Operating Characteristics
8.0
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
0 2000 3000 4000 5000
C
L
(pF)
SLEW RATE (V/µs)
1000
SLEW-
SLEW+
ALL OUTPUTS LOADED
3kΩ II C
L
TRANSMITTER SLEW RATE
vs. LOAD CAPACITANCE
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
-40
40
80
TEMPERATURE (°C)
TRANSMITTER OUTPUT VOLTAGE (V-, V+)
0
-3.7V EIA/TIA-562
T_
OUT
+
TRANSMITTER OUTPUT VOLTAGE
vs. TEMPERATURE
T_
OUT
-
+3.7V EIA/TIA-562
ALL TRANSMITTERS LOADED 3kΩ
.....
.....
6
5
4
3
2
1
0
-1
-2
-3
-4
-5
-6
0 2000 3000 4000 5000
C
L
(pF)
TRANSMITTER OUTPUT VOLTAGE (V-, V+)
1000
T_
OUT
-
T_
OUT
+
ALL TRANSMITTERS
LOADED 3kΩ II C
L
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE, TO 231kbps
38
36
34
32
30
28
26
24
22
20
2.5 3.5 4.0
V
CC
(V)
SUPPLY CURRENT (mA)
3.0
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
ALL TRANSMITTERS LOADED 3kΩ
4.5 5.0 5.5
38
36
34
32
30
28
26
24
22
-40
40
80
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
0
SUPPLY CURRENT
vs. TEMPERATURE
VCC = +2.7V
ALL TRANSMITTERS LOADED 3kΩ
VCC = +3.3V
55
50
45
40
35
30
25
20
0
100
150
DATA RATE (kbps)
SUPPLY CURRENT (mA)
50
SUPPLY CURRENT
vs. TRANSMITTER DATA RATE
1 OUTPUT LOADED
3kΩ II 2500pF
2 OUTPUTS LOADED
3kΩ II 2500pF
3 OUTPUTS LOADED
3kΩ II 2500pF
200 250
60
55
50
45
40
35
-40
40
80
TEMPERATURE (°C)
SUPPLY CURRENT (µA)
0
SUPPLY CURRENT
vs. TEMPERATURE
VCC = +2.7V
VCC = +3.3V
SHDN = 0, EN = 1
ALL TRANSMITTERS LOADED 3kΩ
__________________________________________Typical Operating Characteristics
(VCC= 3.3V, C1A = C1B = C2 = C4 = 0.33µF, C3 = 0.68µF, TA=+25°C, unless otherwise noted.)
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
_______________________________________________________________________________________ 5
INPUT
OUTPUT
t
PLHT
0V
V
OH
0V
V
OL
t
PHLT
+3V
Figure 1. Transmitter Propagation Delay Timing
INPUT
OUTPUT
t
PHLR
t
PHLS
V
CC
0V
t
PLHR
t
PLHS
50%
50%
+3V
50%
GND
50%
Figure 2. Receiver Propagation Delay Timing
______________________________________________________________Pin Description
PIN NAME FUNCTION
28
V+ Positive charge-pump output, typically 5.8V
2, 5 C1A+, C1A- Terminals for positive charge-pump capacitor
3, 4 C1B+, C1B- Terminals for positive charge-pump capacitor
6, 7, 8, 9, 10 R_
OUT
TTL/CMOS Receiver Outputs.
11, 12, 13 T_
IN
TTL/CMOS Driver Inputs
14 EN Receiver Enable, see
Shutdown and Enable Control
section.
15
SHDN
Shutdown Control, see
Shutdown and Enable Control
section.
16, 17, 18 T_
OUT
EIA/TIA-562 Driver Outputs
19, 20, 21, 22, 23 R_
IN
EIA/TIA-562 Receiver Inputs
24, 25 C2+, C2- Terminals for negative charge-pump capacitor
26 V- Negative charge-pump output, typically -5.2V
27 GND Ground
1V
CC
+2.7V to +5.25V Supply Voltage
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
6 _______________________________________________________________________________________
_______________Detailed Description
The MAX562 has three sections: the charge-pump voltage
converter, the drivers (transmitters), and the receivers.
Charge-Pump Voltage Converter
The charge-pump voltage converter is used to produce a
positive and a negative supply to drive the transmitters. The
positive voltage (V+) is generated by a regulated charge
pump working as either a doubler or a tripler (depending on
the VCClevel) and using capacitors C1A, C1B and C3 (see
Typical Operating Circuit
). The negative voltage (V-) derives
from V+ using a simple charge-pump inverter that employs
capacitors C2 and C4.
These charge-pump converters are regulated to give output
voltages of +5.8V and -5.2V. Having regulated supplies
generated on-chip makes the MAX562's performance insensitive to variations in V
CC
from 2.7V to 5.25V, transmitter loading changes, and operating temperature changes.
When
SHDN
is low, the charge pumps are disabled, V+ is
internally connected to VCC, and V- is internally connected to
GND.
EIA/TIA-562 Drivers
The driver output voltage is guaranteed to meet the ±3.7V
EIA/TIA-562 specification over the full range of operating
temperatures and voltages, when each transmitter is
loaded with up to 3kΩ and operated up to 230kbps (see
Typical Operating Characteristics
). The typical driver output voltage swing exceeds ±4V with a 3kΩ load on all
transmitter outputs. The open-circuit output voltage swing
is typically from (V+ - 0.7V) to (V- + 0.7V). Output swing is
not significantly dependent on VCCsince the charge
pumps are regulated.
Input thresholds are CMOS and TTL compatible. Connect
unused inputs to V
CC
or to GND.
When
SHDN
is low, the driver outputs are off and their leakage currents are less than 10µA, even if the transmitter
outputs are back-driven between -7V and +15V. Taking
SHDN
low does not disable the receivers.
When
SHDN
and EN are both low, the entire chip is
disabled and all outputs are high impedance. Power
consumption is lowest in this condition. Exiting shutdown
takes about 100µs, but depends on VCC. Figure 5 shows
SHDN
V
OH
V
OL
+3V
0V
OUTPUT DISABLE TIME (tDT)
+3V
-3V
0V
A. TIMING DIAGRAM
1 OR 0 T
X
3k
50pF
B. TEST CIRCUIT
TRANSMITTER
OUTPUTS
Figure 3. Transmitter-Output Disable Timing
EN
V
OH
-1V,
V
OL
+1.6V
R_
IN
R_
OUT
1k
150pF
A. TEST CIRCUIT
B. ENABLE TIMING
EN INPUT
RECEIVER
OUTPUTS
+3V
0V
OUTPUT ENABLE TIME (t
ER
)
V
OH
V
OL
EN
RECEIVER
OUTPUTS
EN
+3V
0V
OUTPUT DISABLE TIME (tDR)
V
OH
-0.5V
VOL +0.5V
EN INPUT
V
OH
V
OL
C. DISABLE TIMING
R_
Figure 4. Receiver-Output Enable and Disable Timing
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
_______________________________________________________________________________________ 7
the MAX562 transmitter outputs when
SHDN
rises. Two
transmitter outputs are shown going to opposite EIA/TIA562 levels (one transmitter input is high, the other is low).
Each transmitter is loaded with 3kΩ in parallel with
2500pF. The transmitter outputs are well behaved, with
no ringing or undesirable transients as they come out of
shutdown.
Driving Multiple Receivers
Each transmitter is designed to drive a single receiver.
Transmitters can be paralleled to drive multiple
receivers.
EIA/TIA-562 Receivers
All 5 receivers are identical and accept EIA/TIA-562 or
EIA/TIA-232 signals. The CMOS receiver outputs swing
between VCCand GND. They are inverting, maintaining
compatibility with the driver outputs.
The guaranteed 0.8V and 2.4V receiver input thresholds are significantly tighter than the ±3.0V thresholds
required by the EIA/TIA-562 specification. This allows
the receiver inputs to respond to TTL/CMOS logic levels as well as EIA/TIA-562/232 levels. Also, the
MAX562's guaranteed 0.8V lower threshold ensures
that receivers shorted to ground will have a logic 1 output. The 5kΩ input resistance to ground ensures that a
receiver with its input left open will also have a logic 1
output.
The receiver inputs have approximately 0.3V hysteresis
when
SHDN
is high. This provides clean output transitions, even with slowly moving input signals with moderate noise and ringing.
The receivers are active when EN is high. When EN is
low, the receiver outputs are high impedance. This
allows wire-OR connection of two EIA/TIA-562 ports (or
ports of different types) at the UART.
The receivers are always active,when EN is high, irrespective of
SHDN
's state. When
SHDN
is high, the
receivers have hysteresis and experience the shortest
propagation delays (typically 100ns falling, 250ns rising). When
SHDN
is low, the receivers have longer
propagation delays (typically 3µs falling, 2µs rising)
and have no hysteresis. The receiver outputs are not
valid for 50µs after
SHDN
goes low.
Shutdown and Enable Control
SHDN
and EN determine the operation of the MAX562
as shown in Table 1.
__________Applications Information
Capacitor Selection
The capacitor type is not critical for proper MAX562
operation. Any low cost ceramic capacitor (e.g., Z5U,
Y5V) is acceptable for operating at room temperature,
0
200 300100
SHDN
5
0
6
4
2
0
-2
-4
VCC = +2.2V VCC = +2.7V VCC = +5.0VVCC = +3.3V
TIME (µs)
VOLTS (V)
Figure 5. Time for Transmitters to Exit Shutdown
Table 1. MAX562 Control Pin Configurations
SHDN
EN
CHARGE-PUMP
OPERATION
STATUS
TRANSMITTERS
T1-T3
RECEIVERS
R1-R5
SUPPLY
CURRENT
TYP (A)
0 0 Shutdown High-Z High-Z 1µ
0 1 Shutdown High-Z Active* 45µ
1 0 Normal Operation Active High-Z 24m
1 1 Normal Operation Active Active 24m
* Active, but with reduced performance (see
EIA/TIA-562 Receivers
section). This is “keep-awake” mode.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8
___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600
© 1993 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
MAX562
Complete 230kbps, 2.7V to 5.25V
Serial Interface for Notebook Computers
and X7R ceramic capacitors are recommended for
operation over the full temperature range.
Larger capacitors may be used for C2 and C4 (see
Typical Operating Circuit
) to reduce ripple on the trans-
mitter output voltages.
Power-Supply Decoupling
In applications that are sensitive to power-supply noise,
decouple VCCto ground with a capacitor similar in
value to that of the C1A and C1B charge-pump capacitors. Connect the bypass capacitor as close as possible to the VCCand GND pins.
V+ and V- as Power Supplies
A small amount of power can be drawn from V+ and V-.
Excessive loads will cause V+ and V- to fall out of
regulation. When V+ or V- are loaded, check for good
regulation over the intended operating temperature
range.
___________________Chip Topography
32128 27 26 25
4
6
7
8
9
10
5
11 12 13 14 15 16 17 18
24
23
22
21
20
19
C1B-
C1A-
R1
OUT
R2
OUT
R3
OUT
R4
OUT
R5
OUT
C1B+
C1A+
V
CC
V+
GNDV-C2+
C2-
R1
IN
R2
IN
R3
IN
R4
IN
R5
IN
T1
IN
T2
IN
T3
IN
EN
SHDN
T3
OUT
T2
OUT
T1
OUT
0.164"
(4.166mm)
0.135"
(3.429mm)
Table 2. Summary of EIA/TIA-232E/V.28 and EIA/TIA-562 Specifications
PARAMETER CONDITION
EIA/TIA-232E/V.28
SPECIFICATION
EIA/TIA-562
SPECIFICATION
Driver Output Voltage
0 Level
3kΩ to 7kΩ load
5.0V to 15.0V 3.7V to 13.2V
1 Level -5.0V to -15.0V -3.7V to -13.2V
Maximum Output Level No load ±25V ±13.2V
Signal Rate (3kΩ ≤ R
L
≤ 7kΩ)
C
L
= 2500pF Up to 20kbps Up to 20kbps
C
L
= 1000pF Not defined Up to 64kbps
Substrate connected to V+
Transistor count: 1892
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