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PDF MAX3387E Data sheet ( Hoja de datos )
| Número de pieza | MAX3387E | |
| Descripción | 3V / 15kV ESD-Protected / AutoShutdown Plus RS-232 Transceiver for PDAs and Cell Phones | |
| Fabricantes | Maxim Integrated | |
| Logotipo |  |
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19-1561; Rev 1; 10/99
3V, ±15kV ESD-Protected, AutoShutdown Plus
RS-232 Transceiver for PDAs and Cell Phones
General Description
The MAX3387E 3V powered EIA/TIA-232 and V.28/V.24
is a communications interface with low power require-
ments, high data-rate capabilities, and enhanced elec-
trostatic discharge (ESD) protection. The MAX3387E
has three receivers and three transmitters. All RS-232
inputs and outputs are protected to ±15kV using the
IEC 1000-4-2 Air-Gap Discharge method, ±8kV using
the IEC 1000-4-2 Contact Discharge method, and
±15kV using the Human Body Model.
A proprietary low-dropout transmitter output stage
enables true RS-232 performance from a +3.0V to
+5.5V supply with a dual charge pump. The charge
pump requires only four small 0.1µF capacitors for
operation from a +3.3V supply. The MAX3387E is capa-
ble of running at data rates up to 250kbps while main-
taining RS-232 compliant output levels.
The MAX3387E has a unique VL pin that allows interop-
eration in mixed-logic voltage systems. Both input and
output logic levels are pin programmable through the
VL pin. The MAX3387E is available in a space-saving
TSSOP package.
Applications
Subnotebook/Palmtop Computers
PDAs and PDA Cradles
Cell Phone Data Cables
Battery-Powered Equipment
Hand-Held Equipment
Peripherals
Pin Configuration
Features
o VL Pin for Compatibility with Mixed-Voltage
Systems
o ±15kV ESD Protection on Rx Inputs and Tx Outputs
o Low 300µA Supply Current
o Guaranteed 250kbps Data Rate
o 1µA AutoShutdown Plus™ with Receivers Active
o Meets EIA/TIA-232 Specifications Down to 3.0V
PART
MAX3387ECUG
MAX3387EEUG
Ordering Information
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
24 TSSOP
24 TSSOP
Typical Operating Circuit
+3.3V
CBYPASS
C1
0.1µF
C2
0.1µF
24 23
1
FORCEOFF
C1+
VCC
3 C1-
4 C2+
MAX3387E
5 C2-
15
VL 2
V+
6
V-
7 T1IN
T1OUT 21
C3
0.1µF
C4
0.1µF
TOP VIEW
C1+ 1
V+ 2
C1- 3
C2+ 4
C2- 5
V- 6
T1IN 7
T2IN 8
INVALID 9
T3IN 10
FORCEON 11
R3OUT 12
MAX3387E
24 FORCEOFF
23 VCC
22 GND
21 T1OUT
20 T2OUT
19 T3OUT
18 R1IN
17 R2IN
16 R3IN
15 VL
14 R1OUT
13 R2OUT
TSSOP
AutoShutdown Plus is a trademark of Maxim Integrated Products.
TTL/CMOS
INPUTS
TTL/CMOS
OUTPUTS
8 T2IN
10 T3IN
14 R1OUT
13 R2OUT
VL
VL
12 R3OUT
VL
9 INVALID
FORCEON
11
GND
22
T2OUT 20
T3OUT 19
R1IN 18
5k
R2IN 17
5k
R3IN 16
5k
RS-232
OUTPUTS
RS-232
INPUTS
________________________________________________________________ Maxim Integrated Products 1
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
1 page  
3V, ±15kV ESD-Protected, AutoShutdown Plus
RS-232 Transceiver for PDAs and Cell Phones
(VCC = VL = +3.3V, TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics
TRANSMITTER OUTPUT VOLTAGE
vs. LOAD CAPACITANCE
7.5
5.0
DATA RATE = 250kbps
2.5 LOAD = 3kΩ IN PARALLEL WITH CL
0
-2.5
-5.0
-7.5
0
1000 2000 3000 4000
LOAD CAPACITANCE (pF)
5000
SLEW RATE vs. LOAD CAPACITANCE
16
14
12
SLEW RATE -
10
8 SLEW RATE +
6
4
2
0
0 1000 2000 3000 4000 5000
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE
vs. DATA RATE
7.5
5.0
LOAD = 3kΩ, 1000pF
2.5 ONE TRANSMITTER
SWITCHING AT DATA
RATE, OTHER
0 TRANSMITTERS
AT 1/8 DATA RATE
-2.5
-5.0
-7.5
0
50 100 150 200
DATA RATE (kbps)
250
SUPPLY CURRENT vs. LOAD CAPACITANCE
60
LOAD = 3kΩ,
ONE TRANSMITTER
50 SWITCHING AT DATA
RATE, OTHER
40 TRANSMITTERS
250kbps
AT 1/8 DATA RATE
30 120kbps
20 20kbps
10
0
0 1000 2000 3000 4000 5000
LOAD CAPACITANCE (pF)
_______________________________________________________________________________________ 5
5 Page 
3V, ±15kV ESD-Protected, AutoShutdown Plus
RS-232 Transceiver for PDAs and Cell Phones
RC
50M to 100M
CHARGE-CURRENT
LIMIT RESISTOR
HIGH-
VOLTAGE
DC
SOURCE
Cs
150pF
RD
330Ω
DISCHARGE
RESISTANCE
STORAGE
CAPACITOR
DEVICE
UNDER
TEST
I
100%
90%
Figure 6a. IEC 1000-4-2 ESD Test Model
IEC 1000-4-2
The IEC 1000-4-2 standard covers ESD testing and
performance of finished equipment; it does not specifi-
cally refer to ICs. The MAX3387E helps you design
equipment that meets Level 4 (the highest level) of IEC
1000-4-2, without the need for additional ESD-protec-
tion components.
The major difference between tests done using the
Human Body Model and IEC 1000-4-2 is higher peak
current in IEC 1000-4-2 because series resistance is
lower in the IEC 1000-4-2 model. Hence, the ESD with-
stand voltage measured to IEC 1000-4-2 is generally
lower than that measured using the Human Body
Model. Figure 6a shows the IEC 1000-4-2 model, and
Figure 6b shows the current waveform for the ±8kV IEC
1000-4-2 Level 4 ESD Contact Discharge test.
The air-gap test involves approaching the device with a
charged probe. The contact-discharge method connects
the probe to the device before the probe is energized.
Machine Model
The Machine Model for ESD tests all pins using a
200pF storage capacitor and zero discharge resis-
tance. Its objective is to emulate the stress caused by
contact that occurs with handling and assembly during
manufacturing. All pins require this protection during
manufacturing, not just RS-232 inputs and outputs.
Therefore, after PC board assembly, the Machine
Model is less relevant to I/O ports.
__________Applications Information
Capacitor Selection
The capacitor type used for C1–C4 is not critical for
proper operation; polarized or nonpolarized capacitors
can be used. The charge pump requires 0.1µF capaci-
10%
tR = 0.7ns to 1ns
30ns
60ns
t
Figure 6b. IEC 1000-4-2 ESD Generator Current Waveform
Table 2. Minimum Required Capacitor
Values
VCC
(V)
3.0 to 3.6
4.5 to 5.5
3.0 to 5.5
C1
(µF)
0.1
0.047
0.22
C2, C3, C4
(µF)
0.1
0.33
1
tors for 3.3V operation. For other supply voltages, see
Table 2 for required capacitor values. Do not use val-
ues smaller than those listed in Table 2. Increasing the
capacitor values (e.g., by a factor of 2) reduces ripple
on the transmitter outputs and slightly reduces power
consumption. C2, C3, and C4 can be increased without
changing C1’s value. However, do not increase C1
without also increasing the values of C2, C3, and C4 to
maintain the proper ratios (C1 to the other capacitors).
When using the minimum required capacitor values,
make sure the capacitor value does not degrade
excessively with temperature. If in doubt, use capaci-
tors with a larger nominal value. The capacitor’s equiva-
lent series resistance (ESR), which usually rises at low
temperatures, influences the amount of ripple on V+
and V-.
______________________________________________________________________________________ 11
11 Page | ||
| Páginas | Total 16 Páginas | |
| PDF Descargar | [ Datasheet MAX3387E.PDF ] | |
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