Datasheet

transmitter is loaded with 3kΩ in parallel with 1000pF.
The transmitter outputs display no ringing or undesir-
able transients as they come out of shutdown. Note that
the transmitters are enabled only when the magnitude
of V- exceeds approximately -3V.
High Data Rates
The MAX3224E/MAX3226E/MAX3244E maintain the
RS-232 ±5.0V minimum transmitter output voltage even
at high data rates. Figure 9 shows a transmitter loop-
back test circuit. Figure 10 shows a loopback test result
at 120kbps, and Figure 11 shows the same test at
250kbps. For Figure 10, all transmitters were driven
simultaneously at 120kbps into RS-232 loads in parallel
with 1000pF. For Figure 11, a single transmitter was dri-
ven at 250kbps, and all transmitters were loaded with
an RS-232 receiver in parallel with 250pF.
The MAX3225E/MAX3227E/MAX3245E maintain the
RS-232 ±5.0V minimum transmitter output voltage at
data rates up to 1Mbps (MegaBaud). Figure 12 shows
a loopback test result with a single transmitter driven at
1Mbps and all transmitters loaded with an RS-232
receiver in parallel with 250pF.
±15kV ESD-Protected, 1µA, 1Mbps 3.0V to 5.5V,
RS-232 Transceivers with AutoShutdown Plus
MAX3224E
MAX3225E
MAX3226E
MAX3227E
MAX3244E
MAX3245E
5kΩ
R_ IN
R_ OUT
FORCEON
C2-
C2+
C1-
C1+
V-
V+
V
CC
C4
C3*
C1
C2
C
BYPASS
V
CC
FORCEOFF
*C3 CAN BE RETURNED TO V
CC
OR GND.
T_ OUT
T_ IN
GND
V
CC
1000pF
Figure 9. Loopback Test Circuit
Figure 10. MAX3224E/MAX3226E/MAX3244E Loopback Test
Result at 120kbps
2μs/div
T1IN
T1OUT
R1OUT
5V/div
5V/div
5V/div
V
CC
= 3.3V
Figure 11. MAX3224E/MAX3226E/MAX3244E Loopback Test
Result at 250kbps
2μs/div
T1IN
T1OUT
R1OUT
5V/div
5V/div
5V/div
V
CC
= 3.3V
Figure 12. MAX3225E/MAX3227E/MAX3245E Loopback Test
Result at 1Mbps
200ns/div
T1IN
T1OUT
R1OUT
5V/div
5V/div
5V/div
V
CC
= 3.3V
Maxim Integrated
15
MAX3224E/MAX3225E/
MAX3226E/MAX3227E/MAX3244E/MAX3245E