ISL83387E Intersil Corporation, ISL83387E Datasheet - Page 10

• Manufacturer Part Number: ISL83387E
• Description: +/-15kV ESD Protected/+3#V to +5.5V/ 1Microamp/ 250kbps/ RS-232 Transceivers with Enhanced Automatic Powerdown and a Separate Logic Supply
• Manufacturer: Intersil Corporation

High Data Rates
The ISL83387E maintains 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.
5V/DIV
2V/DIV
FIGURE 8. TRANSMITTER OUTPUTS WHEN EXITING
FIGURE 9. TRANSMITTER LOOPBACK TEST CIRCUIT
V
V
C
C
CC
CC
1
2
V
C1 - C4 = 0.1 F
+
+
CC
= +3.3V
POWERDOWN
FORCEOFF
0.1 F
C1+
C1-
C2+
C2-
T
R
FORCEON
FORCEOFF
IN
OUT
+
TIME (20 s/DIV.)
ISL83387E
V
10
CC
T
V
OUT
L
R
5K
V+
V-
IN
T2
T1
+
+
C
C
1000pF
3
4
ISL83387E
Interconnection with 3V and 5V Logic
Standard 3.3V powered RS-232 devices interface well with
3V and 5V powered TTL compatible logic families (e.g., ACT
and HCT), but the logic outputs (e.g., R
the V
CD4000. The ISL83387E V
By connecting V
the logic device, the ISL83387E logic outputs will swing from
GND to the logic V
All pins on the 3V interface devices include ESD protection
structures, but the ISL83387E incorporates advanced
structures which allow the RS-232 pins (transmitter outputs
and receiver inputs) to survive ESD events up to 15kV. The
RS-232 pins are particularly vulnerable to ESD damage
because they typically connect to an exposed port on the
exterior of the finished product. Simply touching the port
pins, or connecting a cable, can cause an ESD event that
might destroy unprotected ICs. These new ESD structures
protect the device whether or not it is powered up, protect
5V/DIV.
5V/DIV.
15kV ESD Protection
R1
R1
T1
T1
T1
T1
OUT
OUT
OUT
OUT
IH
IN
IN
level of 5V powered CMOS families like HC, AC, and
V
C1 - C4 = 0.1 F
V
C1 - C4 = 0.1 F
FIGURE 10. LOOPBACK TEST AT 120kbps
FIGURE 11. LOOPBACK TEST AT 250kbps
CC
CC
= +3.3V
= +3.3V
L
to the same supply (1.8V to 5V) powering
CC
.
L
supply pin solves this problem.
2 s/DIV.
5 s/DIV.
OUTS
) fail to reach