ADUC836 datasheet(29/80 Pages) AD

29 / 80 page

REV. A

ADuC834

–29–

Like EEPROM, Flash memory can be programmed in-system at

a byte level, although it must first be erased; the erase being

performed in page blocks. Thus, Flash memory is often and

more correctly referred to as Flash/EE memory.

FLASH/EE MEMORY

TECHNOLOGY

SPACE EFFICIENT/

DENSITY

IN-CIRCUIT

REPROGRAMMABLE

EPROM

TECHNOLOGY

EEPROM

TECHNOLOGY

Figure 15. Flash/EE Memory Development

Overall, Flash/EE memory represents a step closer to the ideal

memory device that includes nonvolatility, in-circuit program-

mability, high density, and low cost. Incorporated in the

ADuC834, Flash/EE memory technology allows the user to

update program code space in-circuit, without the need to replace

onetime programmable (OTP) devices at remote operating nodes.

Flash/EE Memory and the ADuC834

The ADuC834 provides two arrays of Flash/EE memory for

user applications. 62 Kbytes of Flash/EE Program space are

provided on-chip to facilitate code execution without any exter-

nal discrete ROM device requirements. The program memory

can be programmed in-circuit, using the serial download mode

provided, using conventional third party memory programmers,

or via any user defined protocol in User Download (ULOAD) Mode.

A 4 Kbyte Flash/EE Data Memory space is also provided on-chip.

This may be used as a general-purpose, nonvolatile scratchpad

area. User access to this area is via a group of seven SFRs. This

space can be programmed at a byte level, although it must first

be erased in 4-byte pages.

ADuC834 Flash/EE Memory Reliability

The Flash/EE Program and Data Memory arrays on the ADuC834

are fully qualified for two key Flash/EE memory characteristics,

namely Flash/EE Memory Cycling Endurance and Flash/EE

Memory Data Retention.

Endurance quantifies the ability of the Flash/EE memory to be

cycled through many Program, Read, and Erase cycles. In real

terms, a single endurance cycle is composed of four independent,

sequential events. These events are defined as:

a. initial page erase sequence

b. read/verify sequence

c. byte program sequence

d. second read/verify sequence

In reliability qualification, every byte in both the program and

data Flash/EE memory is cycled from 00H to FFH until a first

fail is recorded, signifying the endurance limit of the on-chip

Flash/EE memory.

As indicated in the specification pages of this data sheet, the

ADuC834 Flash/EE memory endurance qualification has been

carried out in accordance with JEDEC Specification A117 over

the industrial temperature range of –40

°C, +25°C, +85°C, and

+125

°C. The results allow the specification of a minimum

endurance figure over supply and temperature of 100,000

cycles, with an endurance figure of 700,000 cycles being typical

of operation at 25

°C.

Retention quantifies the ability of the Flash/EE memory to retain

its programmed data over time. Again, the ADuC834 has been

qualified in accordance with the formal JEDEC Retention Life-

time Specification (A117) at a specific junction temperature

(TJ = 55

°C). As part of this qualification procedure, the

Flash/EE memory is cycled to its specified endurance limit

described above, before data retention is characterized. This

means that the Flash/EE memory is guaranteed to retain its data

for its full specified retention lifetime every time the Flash/EE

memory is reprogrammed. It should also be noted that retention

lifetime, based on an activation energy of 0.6 eV, will derate

with TJ as shown in Figure 16.

TJ JUNCTION TEMPERATURE – C

250

200

150

100

110

300

100

ADI SPECIFICATION

100 YEARS MIN.

AT T

J = 55 C

Figure 16. Flash/EE Memory Data Retention

A single Flash/EE

Memory Endurance

Cycle

ADUC836 Datasheet(PDF) 29 Page - Analog Devices

ADUC836 Datasheet(HTML) 29 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80

Datasheet Download

Link URL