Rainbow Electronics MAX13237E - Manual (Page 14)

MAX13234E–MAX13237E
3Mbps RS-232 Transceivers with
Low-Voltage Interface
14 ______________________________________________________________________________________
2 μs/div
T1IN
T1OUT
R1OUT
3V/div
5V/div
5V/div
V CC = 3.3V
Figure 12. Loopback Test Results at 120kbps
100ns/div
T1IN
T1OUT
R1OUT
3.3V/div
5V/div
3.3V/div
V CC = 3.3V
Figure 13. Loopback Test Results at 3Mbps
T_IN
R_OUT
FORCEON
FORCEOFF
C1+
C1-
C2+
C2-
*C3 CAN BE RETURNED TO V
CC
OR GND.
V
L
V
CC
1.62V to V CC V CC
V+
V-
C
BYPASS2
GND
T_OUT
R_IN
MAX13236E
MAX13237E
5k Ω
C4
1000pF
C3*
C1
C2
C
BYPASS1
V CC
Figure 11. Loopback Test Circuit
Chip Information
PROCESS: BiCMOS
High Data Rates
The MAX13234E–MAX13237E maintain the RS-232 ±5V
minimum transmitter output voltage even at high data
rates. Figure 11 shows a transmitter loopback test cir-
cuit. Figure 12 shows a loopback test result at
120kbps, and Figure 13 shows the same test at 3Mbps.
In Figure 12, all transmitters were driven simultaneously
at 120kbps into RS-232 loads in parallel with 1000pF.
In Figure 13, a single transmitter was driven at 3Mbps,
and all transmitters were loaded with an RS-232 receiv-
er in parallel with 150pF.