ICL3221ECAZ-T Intersil, ICL3221ECAZ-T Datasheet - Page 10

• Manufacturer Part Number: ICL3221ECAZ-T
• Description: IC TXRX SGL RS232 3-5.5V 16SSOP
• Manufacturer: Intersil
• Type: Transceiverr

Specifications of ICL3221ECAZ-T

• Package / Case: 16-SSOP
• Mounting Type: Surface Mount
• Voltage - Supply: 3 V ~ 5.5 V
• Number Of Drivers/receivers: 1/1
• Protocol: RS232
• Peak Reflow Compatible (260 C): Yes
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Detailed Description
ICL32XXE interface ICs operate from a single +3V 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. The circuit is divided into three sections:
charge pump, transmitters and receivers.
Charge-Pump
Intersil’s new ICL32XXE family utilizes 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 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 at V
See the “Capacitor Selection” section, and Table 3 for
capacitor recommendations for other operating conditions.
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.
Except for the ICL3232E, 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 (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.
Receivers
All the ICL32XXE devices contain standard inverting
receivers that three-state (except for the ICL3232E) via the
EN or FORCEOFF control lines. Additionally, the two
ICL324XE products include noninverting (monitor) receivers
(denoted by the R
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
hysteresis to increase noise immunity and decrease errors
due to slow input signal transitions.
CC
CC
increases. Connect unused inputs to GND for the best
= 0V). The receivers’ Schmitt trigger input stage uses
CC
OUTB
≥ 3.3V, R
ICL3221E, ICL3222E, ICL3223E, ICL3232E, ICL3241E, ICL3243E
label) that are always active,
L
10
= 3kΩ, and C
CC
≥ 3.0V, with one
L
= 250pF, one
CC
= 3.3V.
CC
The ICL3221E, ICL3222E, ICL3223E, ICL3241E inverting
receivers disable only when EN is driven high. ICL3243E
receivers disable during forced (manual) powerdown, but not
during automatic powerdown (see Table 2).
ICL3241E and ICL3243E monitor receivers remain active
even during manual powerdown and forced receiver disable,
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.
Pin Compatible Replacements for 5V Devices
The ICL3221E, ICL3222E, ICL3232E are pin compatible
with existing 5V RS-232 transceivers - see the Features
section on the front page for details.
This pin compatibility coupled with the low I
operating supply range, make the ICL32XXE potential lower
power, higher performance drop-in replacements for existing
5V applications. As long as the ±5V RS-232 output swings
are acceptable, and transmitter input pull-up resistors aren’t
required, the IICL32XXE should work in most 5V
applications.
When replacing a device in an existing 5V application, it is
acceptable to terminate C
Operating Circuit. Nevertheless, terminate C
possible, as slightly better performance results from this
configuration.
Powerdown Functionality
(Except ICL3232E)
The already low current requirement drops significantly
when the device enters powerdown mode. In powerdown,
supply current drops to 1µA, because the on-chip charge
pump turns off (V+ collapses to V
and the transmitter outputs three-state. Inverting receiver
outputs may or may not disable in powerdown; refer to
Table 2 for details. This micro-power mode makes these
devices ideal for battery powered and portable applications.
FIGURE 1. INVERTING RECEIVER CONNECTIONS
-25V ≤ V
RIN
R
GND
V
XIN
CC
≤ +25V
CC
= 5.5V, during normal operation (not in
3
5kΩ
to V
CC
CC
as shown on the Typical
, V- collapses to GND),
GND ≤ V
R
XOUT
CC
ROUT
3
to GND if
and wide
≤ V
March 8, 2005
CC
FN4910.18