HIN201 thru HIN213
Receivers
Detailed Description
The receiver inputs accept up to ±30V while presenting the
required 3kΩ to 7kΩ input impedance even if the power is off
(V = 0V). The receivers have a typical input threshold of
1.3V which is within the ±3V limits, known as the transition
region, of the RS-232 specifications. The receiver output is
The HIN201 thru HIN213 family of RS-232
transmitters/receivers are powered by a single +5V power
supply (except HIN201), 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.
CC
0V to V . The output will be low whenever the input is
CC
greater than 2.4V and high whenever the input is floating or
driven between +0.8V and -30V. The receivers feature 0.5V
hysteresis (except during shutdown) to improve noise
rejection. The receiver Enable line (EN, on HIN205, HIN206
and HIN211, EN on HIN213) when unasserted, disables the
receiver outputs, placing them in the high impedance mode.
The receiver outputs are also placed in the high impedance
state when in shutdown mode (except HIN213 R4 and R5).
Charge Pump
An equivalent circuit of the charge pump is illustrated in
Figure 1. 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
. During phase two, the voltage on C1 is added to V
,
CC
CC
V+
producing a signal across C3 equal to twice V . During
CC
phase two, C2 is also charged to 2V , and then during
CC
V
CC
phase one, it is inverted with respect to ground to produce a
400kΩ
300Ω
signal across C4 equal to -2V . The charge pump accepts
T
XIN
CC
T
OUT
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.
GND < T
< V
CC
XIN
V-
V- < V
TOUT
< V+
FIGURE 2. TRANSMITTER
V
CC
R
XIN
R
OUT
-30V < R
< +30V
XIN
GND < V
ROUT
< V
CC
5kΩ
During shutdown mode (HIN205, HIN206 and HIN211,
GND
SD = V , HIN213, SD = 0V) the charge pump is turned off,
CC
FIGURE 3. RECEIVER
V+ is pulled down to V , V- is pulled up to GND, and the
CC
supply current is reduced to less than 10µA. The transmitter
outputs are disabled and the receiver outputs (except for
HIN213, R4 and R5) are placed in the high impedance state.
T
OR
R
IN
IN
Transmitters
T
OUT
OR
V
OL
The transmitters are TTL/CMOS compatible inverters which
translate the inputs to RS-232 outputs. The input logic
V
OL
R
OUT
t
t
PLH
PHL
threshold is about 26% of V , or 1.3V for V
= 5V. A logic
CC
CC
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
t
t
PHL + PLH
2
AVERAGE PROPAGATION DELAY =
FIGURE 4. PROPAGATION DELAY DEFINITION
HIN213 Operation in Shutdown
The HIN213 features two receivers, R4 and R5, which
remain active in shutdown mode. During normal operation
the receivers propagation delay is typically 0.5µs. This
propagation delay may increase slightly during shutdown.
When entering shut down mode, receivers R4 and R5 are
transmitters driving 3kΩ minimum load impedance, V
=
CC
4.5V, and maximum allowable operating temperature. The
transmitters have an internally limited output slew rate which
is less than 30V/µs. The outputs are short circuit protected
and can be shorted to ground indefinitely. The powered
down output impedance is a minimum of 300Ω with ±2V
not valid for 80µs after SD = V . When exiting shutdown
IL
mode, all receiver outputs will be invalid until the charge
pump circuitry reaches normal operating voltage. This is
typically less than 2ms when using 0.1µF capacitors.
applied to the outputs and V
= 0V.
CC
3-10