ISL3333EVAL1Z Intersil, ISL3333EVAL1Z Datasheet - Page 15

• Manufacturer Part Number: ISL3333EVAL1Z
• Description: EVAL BOARD 1 FOR ISL3333
• Manufacturer: Intersil

Specifications of ISL3333EVAL1Z

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

.
ISL333x Advantages
These dual protocol ICs offer many parametric
improvements vs those offered on competing dual protocol
devices. Some of the major improvements are:
• 3.3V Supply Voltage - Eliminates the 5V supply that
• 15kV Bus Pin ESD - Eases board level requirements
• Full Failsafe RS-485 Rx - Eliminates bus biasing
• Selectable RS-485 Data Rate - Up to 20Mbps, or slew
• High RS-232 Data Rate - >250kbps
• Lower Tx and Rx Skews - Wider, consistent bit widths
• Lower I
• Flow-Thru Pinouts - Tx, Rx bus pins on one side/logic
Packaging - Smaller (QFN) and Pb-free.
RS-232 Mode
Rx Features
RS-232 receivers invert and convert RS-232 input levels
(±3V to ±25V) to the standard TTL/CMOS levels required by
a UART, ASIC, or µcontroller serial port. Receivers are
designed to operate at faster data rates than the drivers, and
they feature very low skews (18ns) so the receivers
contribute negligibly to bit width distortion. Inputs include the
standards required 3kΩ to 7kΩ pull-down resistor, so unused
inputs may be left unconnected. Rx inputs also have built-in
hysteresis to increase noise immunity, and to decrease
erroneous triggering due to slowly transitioning input signals.
Rx outputs are short circuit protected, and are only
tristatable when the entire IC is shutdown (SHDN) via the
powers just the interface IC
rate limited for low EMI and fewer termination issues
pins on the other, for easy routing to connector/UART
ISL333X (MASTER)
OR NC
1kΩ
CC
DY
DE
RA
- Max I
D
R
CC
GND
is 2x to -4x lower than competition
+3.3V
V
CC
Y
Z
A
B
15
+
R
0.1µF
T
FIGURE 10. TYPICAL RS-422 NETWORK
ISL3332, ISL3333
+5V
GENERIC 422 Rx (SLAVE)
0.1µF
V
CC
RO
B
R
ON/OFF pin, or via the active low RXEN pins available on
the QFN package option (see “ISL3333 Special Features” for
more details).
Tx Features
RS-232 drivers invert and convert the standard TTL/CMOS
levels from a UART, or µcontroller serial port to RS-232
compliant levels (±5V minimum). The Tx delivers these
compliant output levels even at data rates of 400kbps, with
loads of 500pF, and with one output in each port switching at
this high rate. The drivers are designed for low skew
(typically 12% of the 400kbps bit width), and are compliant to
the RS-232 slew rate spec (4 to 30V/μs) for a wide range of
load capacitances. Tx inputs float if left unconnected, and
may cause I
unused inputs to GND.
Tx outputs are short circuit protected, and incorporate a
thermal SHDN feature to protect the IC in situations of
severe power dissipation - see the RS-485 section for more
details. All drivers disable in SHDN, or when the 3.3V power
supply is off, and a port’s drivers also disable via the
corresponding DENX pin (see “ISL3333 Special Features”
for more details) available on the QFN package option (see
Tables 2 and 3 and the “Low Power Shutdown” section). The
ISL3332’s SHDN function is useful for disabling the outputs if
both ports will always be disabled together (e.g., used as a
four transceiver RS-232 port), and if it is acceptable for the
Rx to be disabled as well.
Charge Pumps
The on-chip charge pumps create the RS-232 transmitter
power supplies (typically +5.7/-5.3V) from a single supply as
low as 3.15V, and are enabled only if either port is
configured for RS-232 operation. The efficient design
requires only four small 0.1μF capacitors for the voltage
doubler and inverter functions. By operating discontinuously
(i.e., turning off as soon as V+ and V- pump up to the
RE
A
GND
CC
increases. For the best results, connect
GENERIC FULL DUPLEX 422 XCVR (SLAVE)
0.1µF
+
R
T
Y
Z
A
B
GND
+5V
V
CC
R
D
RO
DI
May 27, 2008
FN6362.0