HIN201 Просмотр технического описания (PDF) - Intersil

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HIN201

+5V Powered RS-232 Transmitters/Receivers with 0.1Microfarad External Capacitors

Intersil 

HIN201 thru HIN213

Detailed Description

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.

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

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 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 (HIN205, HIN206 and HIN211,

SD = VCC, HIN213, SD = 0V) 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 10µA. 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

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

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 impedance, VCC =

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

applied to the outputs and VCC = 0V.

Receivers

The receiver inputs accept up to ±30V while presenting the

required 3kΩ to 7kΩ input impedance even if the power is off

(VCC = 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

0V to VCC. The output will be low whenever the input 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

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).

V+

VCC

400kΩ

TXIN

GND < TXIN < VCC

V-

300Ω

TOUT

V- < VTOUT < V+

FIGURE 2. TRANSMITTER

VCC

RXIN

-30V < RXIN < +30V

5kΩ

GND

ROUT

GND < VROUT < VCC

FIGURE 3. RECEIVER

TIN

OR

RIN

TOUT

OR

ROUT

tPHL

tPLH

VOL

VOL

AVERAGE

PROPAGATION

DELAY

=

tPHL

+

2

tPLH

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

not valid for 80µs after SD = VIL. When exiting shutdown

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.

3-10

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