ETL9345 datasheet(13/27 Pages) STMICROELECTRONICS

13 / 27 page

segment blanking for a multiplexed display. Avai-

lable on L outputs only.

g. TRI-STATE® Push-Pull - an enhancement-

mode device to ground and VCC. These outputs

are TRI-STATE outputs, allowing for connection

of these outputs to a data bus shared by other

bus drivers. Available on L outputs only.

ETL9444, L9445 inputs have the following optio-

nal configurations :

h. An on-chip depletion load device to VCC.

i. A Hi-Z input which must be driven to a ”1” or ”0”

by external components.

The above input and output configurations share

common enhancement-mode and depletion-mode

devices. Specifically, all configurations use one or

more of six devices (numbered 1-6, respectively).

Minimum and maximum current (IOUT and VOUT

curves are given in figure 6 for each of these devices

to allow the designer to effectively use these I/O

configurations in designing a system.

The SO, SK outputs can be configured as shown in

a., b., or c. The D and G outputs can be configured

as shown in a. or b. Note that when inputting data

to the G ports, the G outputs should be set to ”1”.

The L outputs can be configured as in d., e., f.or g.

An important point to remember if using configura-

tion d.or f. with the L drivers is that even when the

L drivers are disabled, the depletion load device will

source a small amount of current (see figure 6, de-

vice 2) ; however, when the L-lines are used as in-

puts, the disabled depletion device can not be relied

on to source sufficient current to pull an input to logic

”1”.

RAM KEEP-ALIVE OPTION

Selecting CKO as the RAM power supply (VR) al-

lows the user to shut off the chip power supply (VCC)

and maintain data in the RAM.

To insure that RAM data integrity is maintained, the

following conditions must be met :

1. RESET must go low before VCC goes low during

power off ; VCC must go high before RESET goes

high on power-up.

2. VR must be within the operating range of the

chip, and equal to VCC

± 1V during normal ope-

ration.

3. VR must be

≥ 3.3V with VCC off.

ETL9445

If the ETL9444 ls bonded as a 24-pin device, it be-

comes the ETL9445, illustrated in figure 2, ETL9444

Connection Diagrams. Note that the ETL9445 does

not contain the four general purpose IN inputs (IN3-

IN0). Use of this option precludes, of course, use of

the IN options and the interrupt feature, which uses

IN1. All other options are available for the ETL9445.

ETL9444/9445–ETL9344/9345

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