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
= 0.1
F; Unless Otherwise Specified.
Typicals are at T
A
= 25°C
TEST CONDITIONS
TEMP
(°C)
MIN
TYP
MAX
UNITS
PARAMETER
DC CHARACTERISTICS
Supply Current, Enabled
Supply Current, Powerdown
All Outputs Unloaded, SHDN = V
CC
, V
CC
= 3.15V
SHDN = GND
25
25
-
-
0.3
1
1
10
mA
A
LOGIC AND TRANSMITTER INPUTS
Input Logic Threshold Low
Input Logic Threshold High
T
IN
, SHDN
T
IN
, SHDN
V
CC
= 3.3V
V
CC
= 5.0V
Transmitter Input Hysteresis
Input Leakage Current
RECEIVER OUTPUTS
Output Voltage Low
Output Voltage High
RECEIVER INPUTS
Input Voltage Range
Input Threshold Low
V
CC
= 3.3V
V
CC
= 5.0V
Input Threshold High
V
CC
= 3.3V
V
CC
= 5.0V
Input Hysteresis
Input Resistance
TRANSMITTER OUTPUTS
Output Voltage Swing
Output Resistance
Output Short-Circuit Current
Output Leakage Current
V
OUT
=
12V,
V
CC
= 0V or 3V to 5.5V, SHDN = GND
All Transmitter Outputs Loaded with 3k to Ground
V
CC
= V+ = V- = 0V, Transmitter Output =
2V
Full
Full
Full
Full
5.0
300
-
-
5.4
10M
35
-
-
-
60
25
V
mA
A
Full
25
25
25
25
25
25
-25
0.6
0.8
-
-
-
3
-
1.2
1.5
1.5
1.8
0.5
5
25
-
-
2.4
2.4
-
7
V
V
V
V
V
V
k
I
OUT
= 1.6mA
I
OUT
= -1.0mA
Full
Full
-
-
0.4
-
V
V
T
IN
, SHDN
Full
Full
Full
25
Full
-
2.0
2.4
-
-
-
-
-
0.5
0.01
0.8
-
-
-
1.0
V
V
V
V
A
V
CC
-0.6 V
CC
-0.1
FN6001 Rev 4.00
January 16, 2005
Page 4 of 11
ISL83385E
Electrical Specifications
Test Conditions: V
CC
= 3V to 5.5V, C
1
- C
4
= 0.1
F; Unless Otherwise Specified.
Typicals are at T
A
= 25°C
(Continued)
TEST CONDITIONS
TEMP
(°C)
MIN
TYP
MAX
UNITS
PARAMETER
TIMING CHARACTERISTICS
Maximum Data Rate
Receiver Propagation Delay
R
L
= 3kC
L
= 1000pF, One Transmitter Switching
Receiver Input to Receiver
Output, C
L
= 150pF
t
PHL
t
PLH
Full
25
25
25
25
25
25
25
250
-
-
-
-
-
6
4
500
0.15
0.15
100
100
50
-
-
-
-
-
-
-
-
30
30
kbps
s
s
s
ns
ns
V/s
V/s
Transmitter Output Enable Time
Transmitter Skew
Receiver Skew
Transition Region Slew Rate
From SHDN Rising Edge to T
OUT
=
3.7V
t
PHL
- t
PLH
(Note 4)
t
PHL
- t
PLH
C
L
= 150pF to 1000pF
R
L
= 3kto 7k
Measured From 3V to -3V or
C
L
= 150pF to 2500pF
-3V to 3V, V
CC
= 3.3V
ESD PERFORMANCE
RS-232 Pins (T
OUT
, R
IN
)
Human Body Model
IEC61000-4-2 Air Gap Discharge
IEC61000-4-2 Contact Discharge
All Other Pins
NOTE:
4. Transmitter skew is measured at the transmitter zero crossing points.
Human Body Model
25
25
25
25
-
-
-
-
15
15
8
3
-
-
-
-
kV
kV
kV
kV
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.
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.
TABLE 2. POWERDOWN TRUTH TABLE
SHDN TRANSMITTER RECEIVER
INPUT
OUTPUTS
OUTPUTS MODE OF OPERATION
H
L
Active
High-Z
Active
Active
Normal Operation
Manual Powerdown
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.
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
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
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