8-13

Detailed Description

The HIN200 thru HIN213 family of RS-232 transmitters/receiv-

ers are powered by a single +5V power supply (except HIN201

and HIN209), 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 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 gener-

ate +10V and -10V. The nominal clock frequency is

125kHz. During phase one of the clock, capacitor C1 is

then during phase one, it is inverted with respect to ground

pump accepts input voltages up to 5.5V. The output

impedance of the voltage doubler section (V+) is approxi-

mately 200

Ω, and the output impedance of the voltage

inverter section (V-) is approximately 450

Ω. A typical

application uses 0.1

µF 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 (HIN200, HIN206 and HIN211,

supply current is reduced to less than 10

µA. The transmitter

outputs are disabled and the receiver outputs (except for

HIN213, 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 thresh-

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 400k

Ω 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 3k

Ω minimum load

temperature. The transmitters have an internally limited output

slew rate which is less than 30V/

µs. The outputs are short cir-

cuit protected and can be shorted to ground indefinitely. The

powered down output impedance is a minimum of 300

Ω with

Receivers

The receiver inputs accept up to

±30V while presenting the

required 3k

Ω to 7kΩ input impedance even if the power is off

1.3V which is within the

±3V limits, known as the transition

region, of the RS-232 specifications. The receiver output is

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 rejec-

tion. The receiver Enable line (EN, on HIN206, HIN209, 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).

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 0.5

µs. This prop-

agation delay may increase slightly during shutdown. When

entering shut down mode, receivers R4 and R5 are not valid

for 80

receiver outputs will be invalid until the charge pump circuitry

reaches normal operating voltage. This is typically less than

2ms when using 0.1

µF capacitors.

300

Ω

400k

Ω

V-

V+

FIGURE 2. TRANSMITTER

5k

Ω

GND

FIGURE 3. RECEIVER

AVERAGE PROPAGATION DELAY =

2

OR

OR

FIGURE 4. PROPAGATION DELAY DEFINITION

HIN200 thru HIN213