ICL3237IA-T Intersil, ICL3237IA-T Datasheet - Page 7

• Manufacturer Part Number: ICL3237IA-T
• Description: IC 5DRVR/3RCVR RS232 3V 28-TSSOP
• Manufacturer: Intersil
• Type: Transceiverr

Specifications of ICL3237IA-T

• Number Of Drivers/receivers: 5/3
• Protocol: RS232
• Voltage - Supply: 3 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 28-SSOP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Receiver ENABLE Control
This device also features an EN input to control the receiver
outputs. Driving EN high disables all the inverting (standard)
receiver outputs placing them in a high impedance state.
This is useful to eliminate supply current, due to a receiver
output forward biasing the protection diode, when driving the
input of a powered down (V
Figure 2). The enable input has no effect on transmitter nor
monitor (R
MegaBaud Selection
In normal operating mode (MBAUD = GND), the ICL3237
transmitters guarantee a 250kbps data rate with worst-case
loads of 3kΩ in parallel with 1000pF. This provides
compatibility with PC-to-PC communication software, such
as Laplink™.
FIGURE 3. DISABLED RECEIVERS PREVENT POWER DRAIN
POWERED
FIGURE 2. POWER DRAIN THROUGH POWERED DOWN
DOWN
UART
POWERED
DOWN
V
UART
WAKE-UP
GND
CC
LOGIC
OUTB
V
TO
CC
R
T
PERIPHERAL
X
X
SHDN = GND, EN = V
) outputs.
TRANSITION
DETECTOR
Rx
Tx
V
CC
V
SHDN = GND
OUT
R1
V
R1
OUT
= HI-Z
V
OUTB
CC
T1
CC
OUT
= V
IN
7
= GND) peripheral (see
CC
CC
ICL3237
RS-232 CHIP
OLD
V
CURRENT
FLOW
CC
R1
T1
OUT
IN
ICL3237
For higher speed serial communications, the ICL3237
features MegaBaud operation. In MegaBaud operating
mode (MBAUD = V
a 1Mbps data rate with worst-case loads of 3kΩ in parallel
with 250pF for 3.0V < V
the ICL3237 transmitters guarantee a 1Mbps data rate into
worst-case loads of 3kΩ in parallel with 1000pF.
Capacitor Selection
The charge pumps require 0.1µF capacitors for 3.3V
operation. For other supply voltages refer to Table 3 for
capacitor values. 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. C
increased without increasing C
increase C
maintain the proper ratios (C
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 0.1µF bypass capacitor is
adequate. In applications that are particularly sensitive to
power supply noise, decouple V
capacitor of the same value as the charge-pump capacitor C
Connect the bypass capacitor as close as possible to the IC.
Transmitter Outputs when Exiting
Powerdown
Figure 4 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 3kΩ in parallel with 2500pF. Note
that the transmitters enable only when the magnitude of the
supplies exceed approximately 3V.
High Data Rates
The ICL3237 maintains the RS-232
transmitter output voltages even at high data rates. Figure 5
3.15 to 3.6
3.0 to 3.6
4.5 to 5.5
3.0 to 5.5
V
CC
TABLE 3. REQUIRED CAPACITOR VALUES
1
(V)
without also increasing C
CC
Laplink® is a registered trademark of Traveling Software.
), the ICL3237 transmitters guarantee
CC
< 4.5V. For 5V
C
0.047
1
1
0.22
0.22
0.1
(µF)
to the other capacitors).
1
2
’s value, however, do not
CC
, C
3
to ground with a
±
, and C
5V minimum
2
, C
3
±
C
, and C
10% operation,
4
2
, C
can be
0.22
0.33
3
0.1
1.0
, C
4
4
to
(µF)
1
.