Datasheet
9
Detailed Description
The HIN2XXE family of high-speed RS-232
transmitters/receivers are powered by a single +5V power
supply, feature low power consumption, and meet all ElA
RS232C and V.28 specifications. The circuit is divided into
three sections: the charge pump, transmitter, and receiver.
Charge Pump
An equivalent circuit of the charge pump is illustrated in
Figure 3. The charge pump contains two sections: the
voltage doubler and the voltage inverter. Each section is
driven by a two phase, internally generated clock to
generate +10V and -10V. The nominal clock frequency is
125kHz. During phase one of the clock, capacitor C1 is
charged to V
CC
. During phase two, the voltage on C1 is
added to V
CC
, producing a signal across C3 equal to twice
V
CC
. During phase two, C2 is also charged to 2V
CC
, and
then during phase one, it is inverted with respect to ground
to produce a signal across C4 equal to -2V
CC
. The charge
pump accepts input voltages up to 5.5V. The output
impedance of the voltage doubler section (V+) is
approximately 200Ω, and the output impedance of the
voltage inverter section (V-) is approximately 450Ω. A typical
application uses 0.1µF capacitors for C1-C4, however, the
value is not critical. Increasing the values of C1 and C2 will
lower the output impedance of the voltage doubler and
inverter, increasing the values of the reservoir capacitors, C3
and C4, lowers the ripple on the V+ and V- supplies.
During shutdown mode (HIN206E, HIN211E and HIN213E)
the charge pump is turned off, V+ is pulled down to V
CC
, V-
is pulled up to GND, and the supply current is reduced to
less than 10µA. The transmitter outputs are disabled and the
receiver outputs (except for HIN213E, R4 and R5) are
placed in the high impedance state.
Transmitters
The transmitters are TTL/CMOS compatible inverters which
translate the inputs to RS-232 outputs. The input logic
threshold is about 26% of V
CC
, or 1.3V for V
CC
= 5V. A logic
1 at the input results in a voltage of between -5V and V- at
Test Circuits (HIN232E)
FIGURE 1. GENERAL TEST CIRCUIT FIGURE 2. POWER-OFF SOURCE RESISTANCE
CONFIGURATION
14
15
16
9
13
12
11
10
1
2
3
4
5
7
6
8
C1+
V+
C1-
C2+
C2-
V-
R2
IN
T2
OUT
V
CC
T1
OUT
R1
IN
R1
OUT
T1
IN
T2
IN
R2
OUT
GND
+4.5V TO
+5.5V INPUT
3kΩ
T1 OUTPUT
RS-232 ±30V INPUT
TTL/CMOS OUTPUT
TTL/CMOS INPUT
TTL/CMOS INPUT
TTL/CMOS OUTPUT
+
-
0.1µF
C3
+
-
0.1µF
C1
+
-
0.1µF
C2
+
-
0.1µF C4
3kΩ
OUTPUT
RS-232
±30V INPUT
T2
14
15
16
9
13
12
11
10
1
2
3
4
5
7
6
8
C1+
V+
C1-
C2+
C2-
V-
R2
IN
T2
OUT
V
CC
T1
OUT
R1
IN
R1
OUT
T1
IN
T2
IN
R2
OUT
GND
T2
OUT
T1
OUT
V
IN
= ±2V
A
R
OUT
= V
IN
/I
+
-
C1
+
-
C3
+
-
C2
+
-
C4
S1
S2
S5
S6
S3
S4
S7
S8
V
CC
GND
RC
OSCILLATOR
V
CC
GND
V+ = 2V
CC
GND
V
- = - (V+)
C1+
C1
-
C2-
C2+
VOLTAGE INVERTER
VOLTAGE DOUBLER
FIGURE 3. CHARGE PUMP
HIN202E, HIN206E, HIN207E, HIN208E, HIN211E, HIN213E, HIN232E