max214cwit Maxim Integrated Products, Inc., max214cwit Datasheet - Page 9
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max214cwit
Manufacturer Part Number
max214cwit
Description
Max214 Programmable Dte/dce, +5v Rs-232 Transceiver
Manufacturer
Maxim Integrated Products, Inc.
Datasheet
1.MAX214CWIT.pdf
(12 pages)
When using the minimum recommended capacitor
values, make sure the capacitance value does not
degrade excessively as the operating temperature
v a r i e s .
larger nominal value (for example, 2 times larger).
The effective series resistance (ESR) of the capaci-
t o r s m a y v a r y o v e r t e m p e r a t u r e a n d i n c r e a s e
when below 0°C. ESR influences the amount of rip-
ple on V+ and V-, so if low ripple is required over
wide temperature ranges, use larger capacitors or
low-ESR types.
To reduce the output impedance at V+ and V-, use
larger capacitors (up to 10µF). This can be useful
when “stealing” power from V+ or from V-.
Figure 3 shows the MAX214 driver outputs when exiting
shutdown. As they become active, the two driver out-
puts are shown going to opposite RS-232 levels (one
driver input is high, the other is low). Each driver is
loaded with 3kΩ in parallel with 2.5nF.
Decouple V
value as the charge-pump capacitors.
A small amount of power can be drawn from V+ and V-,
although this will reduce noise margins. See the
Output Voltage vs. Load Current graph in the Typical
Operating Characteristics . Increasing the charge-
Driver Outputs when Exiting Shutdown
I f i n d o u b t , u s e c a p a c i t o r s w i t h a
CC
to ground with a capacitor of the same
_______________________________________________________________________________________
V+ and V- as Power Supplies
Power-Supply Bypassing
Programmable DTE/DCE,
+5V RS-232 Transceiver
pump capacitor sizes up to 10µF reduces the imped-
ance of the V+ and V- outputs.
The MAX214 maintains the RS-232 ±5.0V minimum
driver output voltage even at high data rates. The
Typical Operating Characteristics show transmitter out-
put voltage levels driving 3kΩ in parallel with various
capacitive loads at data rates up to 120kbps.
Figure 3. Transmitter Outputs When Exiting Shutdown
+5V
0V
A = TRANSMITTER OUTPUT HIGH, +5V/div
B = TRANSMITTER OUTPUT LOW, +5V/div
C = SHDN INPUT, +5V/div
HORIZONTAL = 200 s
High Data Rates
C
B
+10V
A
+5V
0V
-5V
-10V
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