ST7293 datasheet(52/69 Pages) STMICROELECTRONICS

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ST72E94 - ST72T94

1.4 OPTION BYTE

An additional mode is used to configure the part

for programming of the EPROM. This is set by a

+12.5 voltage applied to the INT/V

PP.

The EPROM memory may be programmed by us-

ing the EPROM Programming Boards (EPB) avail-

able from SGS-THOMSON.

The ROM devices of the ST72 family can be con-

figured through mask options. In EPROM devices,

most mask options are replaced by EPROM bits

grouped in the Option Byte. The configuration of

the device is made by programming the Option

Byte.

The Option Byte is not in the user memory space.

The Option Byte is accessed only if the device is in

programming mode and location 0200h is ad-

dressed. The EPB provides all the functionality to

select and program the Option Byte.

b7 = WIW:

Watchdog in Wait.

1 : Watchdog suspended during Wait

0 : Watchdog active during Wait

b6 = WDMS:

Watchdog Enable Mode.

1 : Watchdog in Software Select Mode

0 : Watchdog in auto-enable Mode

b5 = PBIP:

Port B Input Pull-up.

1 : Pull-up enabled or Port B (when Input)

0 : No Pull-up on Port B

b4 = PCWS:

Port C Wake-up Select.

1 : Port C I/O functions enabled

0 : Port C Interrupt Wake-up Inputs enabled

b3 = PC1S:

PC1 Select.

1 : Timer OCMP1 connected to pin 17

0 : PC1 I/O function connected to pin 17

WIW

WDMS

PBIP

PCWS

PC1S

PC0S

PA0S

PAIP

b2 = PC0S:

PC0 Select.

1 : Timer ICAP connected to pin 18

0 : PC0 I/O function connected to pin 18

b1 = PA0S:

Port A Output Select.

1 : Port A Output is Push-pull

0 : Port A Output is Open-drain

b0 = PAIP:

Port A Input Pull-up.

1 : Pull-up enabled on Port A (when Input)

0 : No Pull-up on Port A

1.5 EPROM ERASURE (ST72E94 ONLY)

The ST72E94 is erased by exposure to high inten-

sity UV light through the transparent window. This

exposure discharges the floating gate to its initial

state through induced photo current.

It is recommended that the ST72E94 be kept out

of direct sunlight because the UV content of sun-

light can cause temporary functional failure. Ex-

tended exposure to room level fluorescent lighting

will also cause erasure. An opaque coating (paint,

tape, label, etc...) should be placed over the pack-

age window if the product is to be operated under

these lighting conditions. Covering the window

also reduces IDD in stop mode due to photo diode

currents.

An Ultraviolet source of wave length 2537 Å yield-

ing a total integrated dosage of 15 Watt-sec/cm is

required to erase the ST72E94. This device will be

erased in 15 to 20 minutes if an UV lamp with a

12mW/cm power rating is placed 1 inch from the

lamp without filters.

1.6 VOLTAGE RANGE

The ST72E94 and ST72T94 operate with a mini-

mum supply voltage of 3.0V when the ST7294 op-

erates from 2.5V.

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