ISL4241E Intersil Corporation, ISL4241E Datasheet - Page 6

• Manufacturer Part Number: ISL4241E
• Description: QFN Packaged, +/-15kV Esd Protected, +2.7V to +5.5V, 10Nanoamp, 250kbps, RS-232 Transmitters/receivers
• Manufacturer: Intersil Corporation

Electrical Specifications
NOTE:
Detailed Description
The ISL424XE operate from a single +2.7V to +5.5V supply,
guarantee a 250kbps 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 even with V
into three sections: The charge pump, the transmitters, and
the receivers.
Charge-Pump
Intersil’s new ISL424XE devices utilize regulated on-chip
dual charge pumps as voltage doublers, and voltage
inverters to generate ±5.5V transmitter supplies from a V
supply as low as 3.0V. This allows them 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.
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.
The devices guarantee a 250kbps data rate for full load
conditions (3kΩ and 1000pF), V
transmitter operating at full speed. Under more typical
conditions of V
transmitter easily operates at 900kbps.
Transmitter inputs float if left unconnected, and may cause
I
performance.
ESD PERFORMANCE
RS-232 Pins (T
All Other Pins
CC
2. Transmitter skew is measured at the transmitter zero crossing points.
increases. Connect unused inputs to GND for the best
PARAMETER
OUT
CC
, R
≥ 3.3V, R
IN
)
CC
L
= 3.0V. The circuit is divided
= 3kΩ, and C
6
Test Conditions: V
Typicals are at T
CC
Human Body Model
IEC61000-4-2 Contact Discharge
IEC61000-4-2 Air Gap Discharge
Human Body Model
≥ 3.0V, with one
L
= 250pF, one
A
CC
= 25
TEST CONDITIONS
ISL4241E, ISL4243E
= 3V to 5.5V, C
o
C (Continued)
CC
1
- C
4
Receivers
All the ISL424XE devices contain standard inverting
receivers that three-state via the EN or FORCEOFF control
lines. Additionally, the ISL424XE products include
noninverting (monitor) receivers (denoted by the R
label) that are always active, regardless of the state of any
control lines. All the receivers convert RS-232 signals to
CMOS output levels and accept inputs up to ±25V while
presenting the required 3kΩ to 7kΩ input impedance (see
Figure 1) even if the power is off (V
Schmitt trigger input stage uses hysteresis to increase noise
immunity and decrease errors due to slow input signal
transitions.
The ISL4241E inverting receivers disable only when EN is
driven high. ISL4243E receivers disable during forced
(manual) powerdown, but not during automatic powerdown
(see Table 2).
ISL424XE monitor receivers remain active even during
manual powerdown, making them extremely useful for Ring
Indicator monitoring. Standard receivers driving powered
down peripherals must be disabled to prevent current flow
through the peripheral’s protection diodes (see Figures 2
and 3). This renders them useless for wake up functions, but
the corresponding monitor receiver can be dedicated to this
task as shown in Figure 3.
Low Power Operation
These 3V devices require a nominal supply current of
0.3mA, even at V
powerdown mode). This is considerably less than the 5mA
to 11mA current required by comparable 5V RS-232
devices, allowing users to reduce system power simply by
switching to this new family.
= 0.1
µ
FIGURE 1. INVERTING RECEIVER CONNECTIONS
-25V ≤ V
F; Unless Otherwise Specified.
RIN
R
GND
V
XIN
CC
≤ +25V
CC
TEMP
(
o
25
25
25
25
C)
= 5.5V, during normal operation (not in
5kΩ
MIN
-
-
-
-
CC
TYP
GND ≤ V
±15
±15
±8
±2
= 0V). The receivers’
R
XOUT
ROUT
MAX
-
-
-
-
≤ V
OUTB
CC
UNITS
kV
kV
kV
kV