HIN232A_06 Datasheet, PDF (4/10 Pages) Intersil Corporation – High Speed +5V Powered RS-232 Transmitters/Receivers

HIN232A
Test Circuits (HIN232A)
0.1µF ^-
C3 ₊
0.1µF ⁺
C1 -
1 C1+
2 V+
3 C1-
V_CC 16
GND 15
T1_OUT 14
0.1µF ⁺
C2 _-
4 C2+
5 C2-
R1_IN 13
R1_OUT 12
6 V-
T1_IN 11
3kΩ ^{0.1µF C4 7 T2}OUT ^T2IN ¹⁰
T2
OUTPUT
8 R2_IN R2_OUT 9
RS-232
±30V INPUT
+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
1 C1+
2 V+
V_CC 16
GND 15
3 C1-
4 C2+
T1_OUT 14
R1_IN 13
5 C2- R1_OUT 12
6 V-
T1_IN 11
7 ^T2OUT T2_IN 10
8 R2_IN R2_OUT 9
R_OUT = V_IN/I T2_OUT
V_IN = ±2V
T1_OUT
A
FIGURE 1. GENERAL TEST CIRCUIT
FIGURE 2. POWER-OFF SOURCE RESISTANCE
CONFIGURATION
V_CC
GND
VOLTAGE DOUBLER
S1
C1+
S2
+
C1
-
S3
C1-
S4
RC
OSCILLATOR
VOLTAGE INVERTER
V+ = 2V_CC ^S5
C2+
S6
+
C3
-
V_CC
GND
S7
+
C2
-
C2-
S8
+
C4
-
GND
V- = - (V+)
FIGURE 3. CHARGE PUMP
Detailed Description
The HIN232A is a high-speed RS-232 transmitter/receiver
that is powered by a single +5V power supply, features low
power consumption, and meets 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.
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 the output,
and a logic 0 results in a voltage between +5V and (V+ -0.6V).
Each transmitter input has an internal 400kΩ pullup resistor so
any unused input can be left unconnected and its output
remains in its low state. The output voltage swing meets the
RS-232C specifications of ±5V minimum with the worst case
conditions of: all transmitters driving 3kΩ minimum load
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