±1 5 k V ES D-P ro t e c t e d , 1 µA, 1 Mb p s , 3 .0 V t o 5 .5 V,
RS -2 3 2 Tra n s c e ive rs w it h Au t o S h u t d o w n P lu s
–7E/MAX3245
______________________________________________________________P in De s c rip t io n
PIN
NAME
FUNCTION
MAX3224E MAX3226E MAX3244E
MAX3225E MAX3227E MAX3245E
Ready to Transmit Output, active-high. READY is enabled high when
V- goes below -4V and the device is ready to transmit.
1
1
—
READY
2
2
3
28
27
C1+
V+
Positive Terminal of Voltage-Doubler Charge-Pump Capacitor
+5.5V generated by the charge pump
3
4
5
4
24
C1-
Negative Terminal of Voltage-Doubler Charge-Pump Capacitor
Positive Terminal of Inverting Charge-Pump Capacitor
Negative Terminal of Inverting Charge-Pump Capacitor
-5.5V generated by the charge pump
5
1
C2+
6
6
2
C2-
7
7
3
V-
8, 17
9, 16
10, 15
13
8
9–11
4–8
15–19
T_OUT
R_IN
R_OUT
RS-232 Transmitter Outputs
RS-232 Receiver Inputs
9
TTL/CMOS Receiver Outputs
Valid Signal Detector Output, active low. A logic high indicates that a valid
RS-232 level is present on a receiver input.
11
12, 13
14
10
11
12
21
12–14
23
INVALID
T_IN
TTL/CMOS Transmitter Inputs
Force-On Input, active high. Drive high to override AutoShutdown Plus,
keeping transmitters and receivers on (FORCEOFF must be high) (Table 1).
FORCEON
GND
18
19
14
15
25
26
Ground
V
CC
+3.0V to +5.5V Single Supply Voltage
Force-Off Input, active low. Drive low to shut down transmitters, receivers
(except R2OUTB), and charge pump. This overrides AutoShutdown Plus
and FORCEON (Table 1).
20
—
16
—
22
20
FORCEOFF
R2OUTB
TTL/CMOS Noninverting Complementary Receiver Outputs. Always active.
The READY outp ut (MAX3224E–MAX3227E) is low
_______________De t a ile d De s c rip t io n
whe n the c ha rg e p ump s a re d is a b le d in s hutd own
mode. The READY signal asserts high when V- goes
below -4V.
Du a l Ch a rg e -P u m p Vo lt a g e Co n ve rt e r
The MAX3224E–MAX3227E/MAX3244E/MAX3245E’s
inte rna l p owe r s up p ly c ons is ts of a re g ula te d d ua l
charge pump that provides output voltages of +5.5V
(doubling charge pump) and -5.5V (inverting charge
pump), over the +3.0V to +5.5V range. The charge
pump operates in discontinuous mode: if the output
volta g e s a re le s s tha n 5.5V, the c ha rg e p ump is
e na b le d ; if the outp ut volta g e s e xc e e d 5.5V, the
charge-pump is disabled. Each charge pump requires
a flying capacitor (C1, C2) and a reservoir capacitor
(C3, C4) to generate the V+ and V- supplies.
E
RS -2 3 2 Tra n s m it t e rs
The tra ns mitte rs a re inve rting le ve l tra ns la tors tha t
convert CMOS-logic levels to 5.0V EIA/TIA-232 levels.
The MAX3224E/MAX3226E/MAX3244E g ua ra nte e a
250kb p s
M A X 3
d a ta
ra te
(1Mb p s ,
M A X 3
for
2
the
7 E /
2
2
5
E
/
2
MAX3245E) with worst-case loads of 3kΩ in parallel with
1000pF, providing compatibility with PC-to-PC com-
LapLink is a trademark of Traveling Software.
_______________________________________________________________________________________
7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
