ST7262 datasheet(135/139 Pages) STMICROELECTRONICS

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15 IMPORTANT NOTES

Refer to Table 32 which provides a list of the trace

codes for each of the recent silicon revisions.

Silicon revisions are identifiable:

– on the device package, by the last letter of the

Trace Code marked on the device package.

– on the box, by the last 3 digits of the Internal

Sales Type printed in the box label.

See also Figure 92. on page 137

Table 32. Device Identification

15.1 A/ D CONVERTER ACCURACY FOR FIRST

CONVERSION

Description

When the ADC is enabled after being powered

down (for example when waking up from HALT,

ACTIVE-HALT or setting the ADON bit in the AD-

CCSR register), the first conversion (8-bit or 10-

bit) accuracy does not meet the accuracy specified

in the datasheet.

Workaround

In order to have the accuracy specified in the da-

tasheet, the first conversion after a ADC switch-on

has to be ignored.

Note:

This limitation does not apply to Flash silicon rev.

G devices (see Table 32).

15.2 A/D CONVERTER CONVERSION SPEED

Description

Following a change in the fabrication location, the

typical ADC conversion speed value for Flash de-

vices has improved from a previous value of 28µs

to 4µs.

When migrating software from Rev X to Rev G de-

vices (refer to Table 32) care should be taken

when using ADC interrupts.

Workaround

Firstly, on Rev G devices, only the use of One-

Shot conversion mode is recommended in con-

nection with ADC interrupts.

In Continuous Conversion mode, to avoid getting

trapped in a continuous interrupt, the ADC inter-

rupt routine must always have sufficient time to ex-

ecute completely before the next ADC conversion

interrupt, especially if the ADC interrupt is disabled

outside of this routine. With the shorter conversion

speed value, the interrupt may not be serviced fast

enough. For this reason, on Rev G devices, the

Continuous Conversion mode is not recommend-

ed in connection with ADC interrupts.

Secondly, in the interests of keeping code portable

between all Flash/ROM versions, using the ADC

as a source of a delayed trigger event is not ad-

vised. However, in such a scenario, a delay loop

should be inserted for Rev G Flash devices to en-

sure that the timing remains the same for any such

ADC delayed trigger events.

Device Type

(Silicon Rev.)

Trace Code marked on device/

Internal Sales Type on box

label

Flash Devices (Rev G)

(Latest Flash silicon)

“xxxxxxxxxG” / 72F62xxxxx$x4

Flash Devices (Rev X)

(Previous Flash silicon)

“xxxxxxxxxX” / 72F62xxxxx$x8

“xxxxxxxxxX” / 72F62xxxxx$x9

ROM Devices (Rev Z)

“xxxxxxxxxZ” / 7262xxxxx$x2

“xxxxxxxxxZ” / 7262xxxxx$x3

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