ISL4221E Datasheet, PDF (9/13 Pages) Intersil Corporation – QFN Packaged, +/-15kV ESD Protected, +2.7V to +5.5V, 150Nanoamp, 250kBps, RS-232 Transmitters/Receivers

ISL4221E, ISL4223E
Note that the transmitters enable only when the magnitude
of the supplies exceed approximately 3V.
5V/DIV.
FORCEOFF
T1
5V/DIV.
T1_IN
2V/DIV.
T1_OUT
T2
V_CC = +3.3V
C1 - C4 = 0.1µF
TIME (20µs/DIV.)
FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING
POWERDOWN
Operation Down to 2.7V
ISL422XE transmitter outputs meet RS-562 levels (±3.7V), at
the full data rate, with V_CC as low as 2.7V. RS-562 levels
typically ensure inter operability with RS-232 devices.
High Data Rates
The ISL422XE maintain the RS-232 ±5V minimum
transmitter output voltages even at high data rates. Figure 9
details a transmitter loopback test circuit, and Figure 10
illustrates the loopback test result at 120kBps. For this test,
all transmitters were simultaneously driving RS-232 loads in
parallel with 1000pF, at 120kBps. Figure 11 shows the
loopback results for a single transmitter driving 1000pF and
an RS-232 load at 250kBps. The static transmitters were
also loaded with an RS-232 receiver.
V_CC
0.1µF
+
+
C₁
+
C₂
V_CC
C1+
V_CC
V+
C1-
ISL422XE
C2+
V-
C2-
T_IN
T_OUT
R_OUT
R_IN
FORCEON
5k
FORCEOFF
+
C₃
+C⁴
1000pF
FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT
R1_OUT
V_CC = +3.3V
C1 - C4 = 0.1µF
5µs/DIV.
FIGURE 10. LOOPBACK TEST AT 120kBps
5V/DIV.
T1_IN
T1_OUT
R1_OUT
V_CC = +3.3V
C1 - C4 = 0.1µF
2µs/DIV.
FIGURE 11. LOOPBACK TEST AT 250kBps
Interconnection with 3V and 5V Logic
The ISL422XE directly interface with 5V CMOS and TTL
logic families. Nevertheless, with the ISL422XE at 3.3V, and
the logic supply at 5V, AC, HC, and CD4000 outputs can
drive ISL422XE inputs, but ISL422XE outputs do not reach
the minimum V_IH for these logic families. See Table 3 for
more information.
TABLE 3. LOGIC FAMILY COMPATIBILITY WITH VARIOUS
SUPPLY VOLTAGES
SYSTEM
POWER-SUPPLY
VOLTAGE
(V)
V_CC
SUPPLY
VOLTAGE
(V)
COMPATIBILITY
3.3
3.3 Compatible with all CMOS
families.
5
5
Compatible with all TTL and
CMOS logic families.
5
3.3 Compatible with ACT and HCT
CMOS, and with TTL. ISL422XE
outputs are incompatible with AC,
HC, and CD4000 CMOS inputs.
9