Datasheet

MAX221
+5V, 1µA, Single RS-232 Transceiver
with AutoShutdown
4 _______________________________________________________________________________________
Typical Operating Characteristics
(V
CC
= +5V, 250kbps data rate, 0.1µF capacitors, transmitter loaded with 3kΩ and C
L
, T
A
= +25°C, unless otherwise noted.)
-10
-6
-8
-2
-4
2
0
4
8
6
10
0
1000
2000
3000
4000
5000
TRANSMITTER OUTPUT
VOLTAGE vs. LOAD CAPACITANCE
MAX221-01
LOAD CAPACITANCE (pF)
TRANSMITTER OUTPUT VOLTAGE (V)
250kbps
250kbps
120kbps
20kbps
20kbps
120kbps
0
10
20
30
40
50
0
1000
2000
3000
4000
5000
SLEW RATE vs.
LOAD CAPACITANCE
MAX221-02
LOAD CAPACITANCE (pF)
SLEW RATE (V/µs)
+SLEW
-SLEW
0
10
20
30
40
50
0
1000
2000
3000
4000
5000
OPERATING SUPPLY
CURRENT vs. LOAD CAPACITANCE
MAX221-03
LOAD CAPACITANCE (pF)
SUPPLY CURRENT (mA)
250kbps
20kbps
120kbps
FUNCTIONPIN NAME
1
EN
Receiver Enable Control. Drive low for normal operation. Drive high to force the receiver output
(ROUT) into a high-impedance state.
2 C1+ Positive Terminal of the Voltage Doubler Charge-Pump Capacitor
3 V+ Positive Voltage Generated by the Charge Pump
7 V- Negative Voltage Generated by the Charge Pump
6 C2- Negative Terminal of the Inverting Charge-Pump Capacitor
5 C2+ Positive Terminal of the Inverting Charge-Pump Capacitor
4 C1- Negative Terminal of the Voltage Doubler Charge-Pump Capacitor
12 FORCEON
Drive high to override automatic circuitry, keeping transmitter and charge pump on.
FORCEOFF must be high (Table 1).
11 TIN TTL/CMOS Transmitter Input
10
INVALID
Output of the Invalid Signal Detector. INVALID is pulled low if no valid RS-232 level is present on
the receiver input.
9 ROUT TTL/CMOS Receiver Output
8 RIN RS-232 Receiver Input
Pin Description
16
FORCEOFF
Force-Off Input, active low. Drive low to shut down transmitter, receiver, and on-board charge
pump. This overrides all automatic circuitry and FORCEON (Table 1).
15 V
CC
+4.5V to +5.5V Supply Voltage
14 GND Ground
13 TOUT RS-232 Transmitter Output