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ISL83385ECA

P1-P3P4-P6P7-P9P10-P11
4
FN6001.4
January 16, 2005
Absolute Maximum Ratings Thermal Information
V
CC
to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
V+ to Ground . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 7V
V- to Ground. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +0.3V to -7V
V+ to V- . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14V
Input Voltages
T
IN
, SHDN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 6V
R
IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25V
Output Voltages
T
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.2V
R
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to V
CC
+0.3V
Short Circuit Duration
T
OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
ESD Rating . . . . . . . . . . . . . . . . . . . . . . . . . See Specification Table
Thermal Resistance (Typical, Note 3)
JA
(°C/W)
18 Ld SOIC Package . . . . . . . . . . . . . . . . . . . . . . . . 75
20 Ld SSOP Package . . . . . . . . . . . . . . . . . . . . . . . 125
Maximum Junction Temperature (Plastic Package) . . . . . . . 150°C
Maximum Storage Temperature Range . . . . . . . . . . . -65°C to 150°C
Maximum Lead Temperature (Soldering 10s) . . . . . . . . . . . . 300°C
(Lead Tips Only)
Operating Conditions
Temperature Range
ISL83385ECX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
ISL83385EIX . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -40°C to 85°C
CAUTION: Stresses above those listed in “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress only rating and operation of the
device at these or any other conditions above those indicated in the operational sections of this specification is not implied.
NOTE:
3.
JA
is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
Electrical Specifications Test Conditions: V
CC
= 3V to 5.5V, C
1
- C
4
= 0.1F; Unless Otherwise Specified.
Typicals are at T
A
= 25°C
PARAMETER TEST CONDITIONS
TEMP
(°C) MIN TYP MAX UNITS
DC CHARACTERISTICS
Supply Current, Enabled All Outputs Unloaded, SHDN
=V
CC
, V
CC
= 3.15V 25 - 0.3 1 mA
Supply Current, Powerdown SHDN = GND 25 - 1 10 A
LOGIC AND TRANSMITTER INPUTS
Input Logic Threshold Low T
IN
, SHDN Full - - 0.8 V
Input Logic Threshold High T
IN
, SHDN V
CC
= 3.3V Full 2.0 - - V
V
CC
= 5.0V Full 2.4 - - V
Transmitter Input Hysteresis 25 - 0.5 - V
Input Leakage Current T
IN
, SHDN Full - 0.01 1.0 A
RECEIVER OUTPUTS
Output Voltage Low I
OUT
= 1.6mA Full - - 0.4 V
Output Voltage High I
OUT
= -1.0mA Full V
CC
-0.6 V
CC
-0.1 - V
RECEIVER INPUTS
Input Voltage Range Full -25 - 25 V
Input Threshold Low V
CC
= 3.3V 25 0.6 1.2 - V
V
CC
= 5.0V 25 0.8 1.5 - V
Input Threshold High V
CC
= 3.3V 25 - 1.5 2.4 V
V
CC
= 5.0V 25 - 1.8 2.4 V
Input Hysteresis 25 - 0.5 - V
Input Resistance 25 3 5 7 k
TRANSMITTER OUTPUTS
Output Voltage Swing All Transmitter Outputs Loaded with 3k to Ground Full 5.0 5.4 - V
Output Resistance V
CC
=V+=V-=0V, Transmitter Output=2V Full 300 10M -
Output Short-Circuit Current Full - 35 60 mA
Output Leakage Current V
OUT
= 12V, V
CC
= 0V or 3V to 5.5V, SHDN =GND Full - - 25 A
ISL83385E
5
FN6001.4
January 16, 2005
Detailed Description
The ISL83385E operates from a single +3V to +5.5V supply,
guarantees a 250kbps minimum data rate, requires only four
small external 0.1F capacitors, features low power
consumption, and meets all ElA RS-232C and V.28
specifications. The circuit is divided into three sections: The
charge pump, the transmitters, and the receivers.
Charge-Pump
Intersil’s new ISL83385E utilizes regulated on-chip dual
charge pumps as voltage doublers, and voltage inverters to
generate 5.5V transmitter supplies from a V
CC
supply as
low as 3.0V. This allows these devices to maintain RS-232
compliant output levels over the 10% tolerance range of
3.3V powered systems. The efficient on-chip power supplies
require only four small, external 0.1F capacitors for the
voltage doubler and inverter functions over the full V
CC
range; other capacitor combinations can be used as shown
in Table 3. The charge pumps operate discontinuously (i.e.,
they turn off as soon as the V+ and V- supplies are pumped
up to the nominal values), resulting in significant power
savings.
Transmitters
The transmitters are proprietary, low dropout, inverting
drivers that translate TTL/CMOS inputs to EIA/TIA-232
output levels. Coupled with the on-chip 5.5V supplies,
these transmitters deliver true RS-232 levels over a wide
range of single supply system voltages.
All transmitter outputs disable and assume a high
impedance state when the device enters the powerdown
mode (see Table 2). These outputs may be driven to 12V
when disabled.
All devices guarantee a 250kbps data rate for full load
conditions (3k and 1000pF), V
CC
3.0V, with one
transmitter operating at full speed. Under more typical
conditions of V
CC
3.3V, R
L
=3k, and C
L
= 250pF, one
transmitter easily operates at 900kbps.
Transmitter inputs float if left unconnected (there are no pull-
up resistors), and may cause I
CC
increases. Connect
unused inputs to GND for the best performance.
Receivers
The ISL83385E contains standard inverting receivers that
convert RS-232 signals to CMOS output levels and accept
inputs up to 30V while presenting the required 3k to 7k
input impedance (see Figure 1) even if the power is off
(V
CC
= 0V). The receivers’ Schmitt trigger input stage uses
TIMING CHARACTERISTICS
Maximum Data Rate R
L
=3kC
L
= 1000pF, One Transmitter Switching Full 250 500 - kbps
Receiver Propagation Delay Receiver Input to Receiver
Output, C
L
= 150pF
t
PHL
25 - 0.15 - s
t
PLH
25 - 0.15 - s
Transmitter Output Enable Time From SHDN Rising Edge to T
OUT
= 3.7V 25 - 100 - s
Transmitter Skew t
PHL
- t
PLH
(Note 4) 25 - 100 - ns
Receiver Skew t
PHL
- t
PLH
25 - 50 - ns
Transition Region Slew Rate R
L
=3kto 7k
Measured From 3V to -3V or
-3V to 3V, V
CC
= 3.3V
C
L
= 150pF to 1000pF 25 6 - 30 V/s
C
L
= 150pF to 2500pF 25 4 - 30 V/s
ESD PERFORMANCE
RS-232 Pins (T
OUT
, R
IN
) Human Body Model 25 - 15 - kV
IEC61000-4-2 Air Gap Discharge 25 - 15 - kV
IEC61000-4-2 Contact Discharge 25 - 8-kV
All Other Pins Human Body Model 25 - 3-kV
NOTE:
4. Transmitter skew is measured at the transmitter zero crossing points.
Electrical Specifications Test Conditions: V
CC
= 3V to 5.5V, C
1
- C
4
= 0.1F; Unless Otherwise Specified.
Typicals are at T
A
= 25°C (Continued)
PARAMETER TEST CONDITIONS
TEMP
(°C) MIN TYP MAX UNITS
TABLE 2. POWERDOWN TRUTH TABLE
SHDN
INPUT
TRANSMITTER
OUTPUTS
RECEIVER
OUTPUTS MODE OF OPERATION
H Active Active Normal Operation
L High-Z Active Manual Powerdown
ISL83385E
6
FN6001.4
January 16, 2005
hysteresis to increase noise immunity and decrease errors
due to slow input signal transitions.
Low Power Operation
This 3V device requires a nominal supply current of 0.3mA,
even at V
CC
= 5.5V, during normal operation (not in
powerdown mode). This is considerably less than the 11mA
current required by comparable 5V RS-232 devices, allowing
users to reduce system power simply by replacing the old
style device with the ISL83385E in new designs.
Powerdown Functionality
The already low current requirement drops significantly
when the device enters powerdown mode. In powerdown,
supply current drops to 1A, because the on-chip charge
pump turns off (V+ collapses to V
CC
, V- collapses to GND),
and the transmitter outputs three-state. This micro-power
mode makes these devices ideal for battery powered and
portable applications.
Software Controlled (Manual) Powerdown
The ISL83385E may be forced into its low power, standby
state via a simple shutdown (SHDN
) pin (see Figure 2).
Driving this pin high enables normal operation, while driving
it low forces the IC into it’s powerdown state. The time
required to exit powerdown, and resume transmission is less
than 100s. Connect SHDN
to V
CC
if the powerdown
function isn’t needed.
Capacitor Selection
These charge pumps only require 0.1F capacitors for the
full operational voltage range. Table 3 lists other acceptable
capacitor values for various supply voltage ranges. Do not
use values smaller than those listed in Table 3. Increasing
the capacitor values (by a factor of 2) reduces ripple on the
transmitter outputs and slightly reduces power consumption.
When using minimum required capacitor values, make sure
that capacitor values do not degrade excessively with
temperature. If in doubt, use capacitors with a larger nominal
value. The capacitor’s equivalent series resistance (ESR)
usually rises at low temperatures and it influences the
amount of ripple on V+ and V-.
Power Supply Decoupling
In most circumstances a 0.1F bypass capacitor is
adequate. In applications that are particularly sensitive to
power supply noise, decouple V
CC
to ground with a
capacitor of the same value as the charge-pump capacitor C
1
.
Connect the bypass capacitor as close as possible to the IC.
Operation Down to 2.7V
ISL83385E transmitter outputs meet RS-562 levels (±3.7V),
at the full data rate, with V
CC
as low as 2.7V. RS-562 levels
typically ensure inter operability with RS-232 devices.
Transmitter Outputs when Exiting
Powerdown
Figure 3 shows the response of two transmitter outputs
when exiting powerdown mode. As they activate, the two
transmitter outputs properly go to opposite RS-232 levels,
with no glitching, ringing, nor undesirable transients. Each
transmitter is loaded with 3kin parallel with 2500pF. Note
that the transmitters enable only when the magnitude of the
supplies exceed approximately 3V.
R
XOUT
GND V
ROUT
V
CC
5k
R
XIN
-25V V
RIN
+25V
GND
V
CC
FIGURE 1. INVERTING RECEIVER CONNECTIONS
FIGURE 2. CONNECTIONS FOR MANUAL POWERDOWN
PWR
SHDN
CPU
I/O
ISL83385E
MGT
LOGIC
UART
TABLE 3. REQUIRED CAPACITOR VALUES
V
CC
(V)
C
1
(F)
C
2
, C
3
, C
4
(F)
3.0 to 3.6 0.1 0.1
4.5 to 5.5 0.047 0.33
3.0 to 5.5 0.1 0.47
ISL83385E
P1-P3P4-P6P7-P9P10-P11

ISL83385ECA

Mfr. #:
Buy ISL83385ECA
Manufacturer:
Renesas / Intersil
Description:
IC TXRX 2/2 FULL RS232 20SSOP
Lifecycle:
New from this manufacturer.
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