ISL4238E Datasheet, PDF (8/17 Pages) Intersil Corporation – QFN Packaged, ±15kV ESD Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps/1Mbps, RS-232 Transceivers with Enhanced Automatic Power-down

ISL4238E, ISL4244E, ISL4245E
Electrical Specifications Test Conditions: ISL4238E V_CC = 3.15V to 5.5V, C₁ to C₄ = 0.1µF; V_CC = 3V, C₁ to C₄ = 0.22µF;
ISL424xE V_CC = 3V to 5.5V, C₁ to C₄ = 0.1µF; Unless Otherwise Specified. Typicals are at T_A = +25°C
PARAMETER
TEST CONDITIONS
TEMP MIN
(°C) (Note 7)
MAX
TYP (Note 7) UNITS
Receiver Output Disable Time
Normal Operation, R_L = 1kΩ to 0.5V_CC, C_L = 15pF
25
-
Full
-
350
500
ns
400
600
ns
Transmitter Output Enable Time Normal Operation, R_L = 3kΩ, C_L = 1000pF
ISL4238E/ISL4244E/ISL4245E
25
-
Full
-
25
40
µs
35
50
µs
Transmitter Output Disable Time Normal Operation, R_L = 3kΩ, C_L = 1000pF
ISL4238E/ISL4244E/ISL4245E
25
-
Full
-
2.5
4
µs
2.7
4
µs
Transition Region Slew Rate
ISL4238E/ISL4244E
V_CC = 3V to 3.6V,
R_L = 3kΩ to 7kΩ,
Measured From 3V to -3V
or -3V to 3V
C_L = 150pF to 1000pF
C_L = 150pF to 2500pF
25
6
Full
6
25
4
Full
4
11
30
V/µs
10
30
V/µs
9
30
V/µs
8
30
V/µs
Transition Region Slew Rate
V_CC = 3V to 3.6V, R_L = 3kΩ to 7kΩ, Measured From 3V to 25
24
ISL4245E
-3V or -3V to 3V, C_L = 150pF to 1000pF
Full
24
40
150 V/µs
35
150 V/µs
ESD PERFORMANCE
RS-232 Pins (T_OUT, R_IN)
Human Body Model
IEC61000-4-2 Air Gap Discharge
25
-
25
-
±15
-
kV
±15
-
kV
IEC61000-4-2 Contact Discharge
25
-
±8
-
kV
All Other Pins
Human Body Model
25
-
±3
-
kV
NOTES:
3. ISL4238E inputs utilize a positive feedback resistor. The input current is negligible when the input is at either supply rail.
4. An “edge” is defined as a transition through the transmitter or receiver input thresholds.
5. Skew is measured at the receiver input switching points (1.4V).
6. Skew is measured at the transmitter zero crossing points.
7. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
Detailed Description
These interface ICs operate from a single +2.7V to +5.5V
supply, guarantee a 250kbps (ISL4238E/ISL4244E)/1Mbps
(ISL4245E) minimum data rate, require only four small
external 0.1µF capacitors, feature low power consumption,
and meet 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 RS-232 family 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 0.1µF capacitors for the
voltage doubler and inverter functions. 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.
Transmitter outputs disable and assume a high impedance
state when the device enters the power-down mode (see Table
2). These outputs may be driven to ±12V when disabled.
The ISL4238E/ISL4244E guarantee a 250kbps data rate for
full load conditions (3kΩ and 1000pF), V_CC ≥ 3.0V, with one
transmitter operating at full speed. Under more typical
conditions of V_CC ≥ 3.3V, R_L = 3kΩ, and C_L = 250pF, one
transmitter easily operates at 1Mbps.
The ISL4245E guarantees a 1Mbps data rate for full load
conditions (3kΩ and 250pF), V_CC ≥ 3.0V, with one
transmitter operating at full speed. Under more typical
conditions of V_CC ≥ 3.3V, R_L = 3kΩ, and C_L = 250pF, one
transmitter easily operates at 1.4Mbps.
Transmitter inputs on the ISL424XE float if left unconnected,
and may cause I_CC increases. Connect unused inputs to
8
FN8038.5
May 13, 2010