MAX3243EETJ+T Maxim Integrated, MAX3243EETJ+T Datasheet - Page 10

• Manufacturer Part Number: MAX3243EETJ+T
• Description: RS-232 Interface IC
• Manufacturer: Maxim Integrated
• Series: MAX3221E, MAX3223E, MAX3243Er

Specifications of MAX3243EETJ+T

• Data Rate: 120 Kbps
• Operating Supply Voltage: 3 V to 5.5 V
• Supply Current: 1 mA
• Operating Temperature Range: 0 C to + 70 C
• Function: Transceiver
• Number Of Drivers: 3
• Number Of I/os: 16
• Number Of Receivers: 5
• Propagation Delay Time Ns: 0.3 us
• Shutdown: Yes

Table 3. R
3.0V to 5.5V, 1.25Gbps/2.5Gbps
LAN Laser Drivers
TEMPCO
impedance). This ensures that the PNP or NPN transistor
is turned off, removing the laser-bias current. (See the
Applications Information section.)
The REF pin provides a controlled reference voltage
dependent upon the voltage at MON. The voltage at REF
is V
at REF determines the laser power when APC is used
with common-cathode lasers. See the Design Procedure
section for information about setting the laser power.
The modulator circuitry consists of an input buffer, current
generator, and high-speed current switch (Figure 4). The
modulator drives up to 30mA of modulation current into
a 25 load.
Many of the modulator performance specifications
depend on the total modulator current (I
To ensure good driver performance, the voltage at
OUT+ and OUT- must not be less than V
The amplitude of the modulation current is set with
resistors at the MODSET and temperature coefficient (TC)
pins. The resistor at MODSET (R
temperature-stable portion of modulation current, while
the resistor at TC (R
increasing portion of the modulation current. Figure 5
shows modulation current as a function of temperature
for two extremes: R
has zero temperature coefficient) and R
(the modulation temperature coefficient is 4000ppm).
Intermediate tempco values of modulation current can
be obtained as described in the Design Procedure sec-
tion. Table 3 is the R
The laser driver can be used with two popular safety
systems. APC maintains laser safety using local feed-
back. Safety features monitor laser driver operation and
(ppm/°C)
10
3500
3000
2500
2000
1500
1000
500
REF
______________________________________________________________________________________
= 2.65 - 2.25(V
R
I
26.7
9.53
5.76
4.12
3.24
2.67
2.26
MOD
(k )
MOD
TC
= 30mA
and R
(k )
1.69
2.49
3.16
4.32
6.49
13.3
R
2.0
TC
TC
TC
TC
CC
is open (the modulation current
and R
MOD
R
) programs the temperature-
I
(k )
53.6
18.7
11.3
8.06
6.19
5.11
4.22
- V
MOD
MOD
MON
Modulation Circuitry
MOD
= 15mA
Selection Table
). A resistor connected
(k )
R
3.65
4.32
5.23
6.49
8.87
13.3
26.7
selection table.
TC
MOD
Safety Circuitry
OUT
) programs the
CC
R
(k )
57.6
34.8
24.9
19.1
15.8
13.3
162
I
MOD
MOD
MOD
) (Figure 1a).
- 1V.
= 5mA
is open
(k )
11.5
13.3
16.2
20.0
26.7
40.2
80.6
R
TC
Figure 3. Bias Generator Circuitry
Figure 4. Laser Modulator Circuitry
IN+
IN-
POL
POL
MD
REF
ENABLE
2.95V
POLARITY_FAULT
MODULATION CURRENT
R
MAX3286
MAX3296
TC
TC
400
400
CONTROLLED REFERENCE VOLTAGE
V
SMOOTH-
CC
GENERATOR
V
0.8V
START
REF
- 0.3V
REF_FAULT
= 2.65 - 2.25 (V
BUFFER
INPUT
4000ppm/ C
REFERENCE
AMPLIFIER
CONTROL
+1.53V
GLITCH
REJECT
+1.97V
POWER-
MODSET
TC_FAULT
MONITOR_FAULT
+1.7V
CC
- V
ENABLE
MON
CURRENT
SWITCH
)
R
MOD
CURRENT AMPLIFIER
COMPARATOR
0.8V
ENABLE
WINDOW
50
V
CC
V
REFERENCE
CC
MOD_FAULT
1.2V
- 540mV
50
MD
FAULT
BIASDRV
MON
OUT+
OUT-