11
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 specications. 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
VCC . During phase two, the voltage on C1 is added to VCC,
producing a signal across C3 equal to twice VCC. During
phase two, C2 is also charged to 2VCC, and then during
phase one, it is inverted with respect to ground to produce a
signal across C4 equal to -2VCC. The charge pump accepts
input voltages up to 5.5V. The output impedance of the
voltage doubler section (V+) is approximately 200
, and the
output impedance of the voltage inverter section (V-) is
approximately 450
. A typical application uses 0.1F
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, HIN213E,
HIN236E and HIN241E) the charge pump is turned off, V+ is
pulled down to VCC, V- is pulled up to GND, and the supply
current is reduced to less than 10
A. 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 VCC, or 1.3V for VCC = 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-
R2IN
T2OUT
VCC
T1OUT
R1IN
R1OUT
T1IN
T2IN
R2OUT
GND
+4.5V TO
+5.5V INPUT
3k
T1 OUTPUT
RS-232
±30V INPUT
TTL/CMOS OUTPUT
TTL/CMOS INPUT
TTL/CMOS OUTPUT
+
-
0.1
F
C3
+
-
0.1
F
C1
+
-
0.1
F
C2
+
-
0.1
F C4
3k
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-
R2IN
T2OUT
VCC
T1OUT
R1IN
R1OUT
T1IN
T2IN
R2OUT
GND
T2OUT
T1OUT
VIN = ±2V
A
ROUT = VIN/I
+
-
C1
+
-
C3
+
-
C2
+
-
C4
S1
S2
S5
S6
S3
S4
S7
S8
VCC
GND
RC
OSCILLATOR
VCC
GND
V+ = 2VCC
GND
V
- = - (V+)
C1+
C1
-
C2
-
C2+
VOLTAGE INVERTER
VOLTAGE DOUBLER
FIGURE 3. CHARGE PUMP
HIN202E thru HIN241E