HI-8596

HOLT INTEGRATED CIRCUITS

4

FUNCTIONAL DESCRIPTION

Figure 1 is a block diagram of the line driver. The HI-8596

requires only a single +3.3V power supply. An integrated

inverting / non-inverting voltage doubler generates the

rail voltages (±6.6V) which are then used to produce the

±5V ARINC-429 output levels.

The internal dual polarity charge pump circuit requires

four external capacitors, two for each polarity gener-

ated by the doubler. CP+ and CP- connect the exter-

nal charge transfer or “fly” capacitor, C

portion of the doubler, resulting in twice V

pin. An output “hold” capacitor, C

V

The inverting or negative portion of the converter works

in a similar fashion, with C

CN+ / CN- and V

Currents for slope control are set by on-chip resistors.

The TX0IN and TX1IN inputs receive logic signals

from a control transmitter chip such as the HI-3584.

TXAOUT and TXBOUT hold each side of the ARINC bus

at Ground until one of the inputs becomes a One. If for

example TX1IN goes high, a charging path is enabled to

5V on an “A” side internal capacitor while the “B” side is

enabled to -5V. The charging current is selected by the

SLP pin. If the SLP pin is high, the capacitor is nominally

charged from 10% to 90% in 1.5μs. If SLP is low, the

rise and fall times are 10μs.

A unity gain buffer receives the internally generated

slopes and differentially drives the ARINC line. Cur-

rent is limited by the series output resistors at each pin.

There are no fuses at the outputs of the HI-8596.

The HI-8596 has 37.5 ohms in series with each TXOUT

output and 5 ohms in series with each AMP output. The

AMP outputs are for applications where external series

resistance is required, typically for lightning protection

devices. Holt Application Note AN-300 describes suit-

able lightning protection schemes.

Tri-stateable outputs allow multiple line drivers to be

connected to the same ARINC 429 bus. Setting TX1IN

and TX0IN both to a logic “1” puts the outputs in the

high-impedance state.

ABSOLUTE MAXIMUM RATINGS

Supply Voltages

V

Power Dissipation at 25

plastic SOIC ........... 1.0W, derate 10mW/

ceramic DIP ......... 0.5W, derate 7mW/

Solder Temperature ......................... 275

Storage Temperature ....................... -65

Note: HEAT SINK on QFN PACKAGE

The HI-8596 driver is available in a small-footprint, thermally

enhanced QFN (chip-scale) package. This package includes

an electrically isolated metal heat sink located on the bottom

surface of the device. This heat sink should be soldered down

to the printed circuit board for optimum thermal dissipation.

RECOMMENDED OPERATING

CONDITIONS

Supply Voltages

V

Temperature Range

Industrial Screening .............. -40

Hi-Temp Screening .............. -55

NOTE: Stresses above absolute maximum ratings or outside recom-

mended operating conditions may cause permanent damage to the

device. These are stress ratings only. Operation at the limits is not

recommended.