Texas Instruments TMS320 - Manual (Page 54)

TMS320 SECOND GENERATION
DEVICES
SPRS010B — MAY 1987 — REVISED NOVEMBER 1990
POST OFFICE BOX 1443

HOUSTON, TEXAS 77001 54
TYPICAL SUPPLY CURRENT CHARACTERISTICS FOR TMS320C25
170
160
150
140
130
120
110
100
90
80
70
60
50
40
30
10
20
4 8 12 16 20 24 28 32 36 40 44 48 52
T
A
= 25  C
I
CC
vs f
(CLKIN)
and V
CC
Normal Operating Mode
f
(CLKIN)
, MHz
V
CC
= 5.50 V
V
CC
= 5.25 V
V
CC
= 5.00 V
V
CC
= 4.75 V
V
CC
= 4.50 V
Im
A
CC,
0
80
70
60
50
40
30
10
20
4 8 12 16 20 24 28 32 36 40 44 48 52
I
CC
vs f
(CLKIN)
and V
CC
Powerdown Mode
f
(CLKIN)
, MHz
Im
A
CC,
V
CC
= 5.50 V
V
CC
= 5.25 V
V
CC
= 5.00 V
V
CC
= 4.75 V
V
CC
= 4.50 V
TMS320C25FNL (PLCC) reflow soldering precautions
Recent tests have identified an industry-wide problem experienced by surface mounted devices exposed to
reflow soldering temperatures. This problem involves a package cracking phenomenon sometimes
experienced by large (e.g., 68-lead) plastic leaded chip carrier (PLCC) packages during surface mount
manufacturing. This phenomenon occur if the TMS320C25FNL is exposed to uncontrolled levels of humidity
prior to reflow solder. This moisture can flash to steam during solder reflow, causing sufficient stress to crack
the package and compromise device integrity. If the TMS320C25FNL is being socketed, no special handling
precautions are required. In addition, once the device is soldered into the board, no special handling precautions
are required.
In order to minimize moisture absorption, TI ships the TMS320C25FNL in “dry pack” shipping bags with a RH
indicator card and moisture-absorbing desiccant. These moisture-barrier shipping bags will adequately block
moisture transmission to allow shelf storage for 12 months from date of seal when stored at less than 60%
relative humidity (RH) and less than 30C. Devices may be stored outside the sealed bags indefinitely if stored
at less than 25% RH and 30C.
Once the bag seal is broken, the devices should be stored at less than 60% RH and 30C as well as reflow
soldered within two days of removal. In the event that either of the above conditions is not met, TI recommends
these devices be baked in a clean oven at 125C and 10% maximum RH for 24 hours. This restores the devices
to their “dry packed” moisture level.
NOTE
Shipping tubes will not withstand the 125
C
baking process. Devices should be transferred to a metal tray or tube be-
fore baking. Standard ESD precautions should be followed.
In addition, TI recommends that the reflow process not exceed two solder cycles and the temperature not
exceed 220C.
If you have any additional questions or concerns, please contact your local TI representative.
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ION