EL1056AC EL1056C
Monolithic High-Speed Pin Driver
Power Down Contd
Supply and Input Bypassing
The Va Ba Vb and Bb leads should be by-
passed very closely with 0 1 mF capacitors pref-
erably chip type There should be a wide ground
plane between bypasses and this can be the heat-
sink copper It is wise to also have a 4 7 mF tanta-
lum bypass capacitor within a couple of inches to
the driver
The logic inputs are active device bases and can
oscillate if presented with inductive lines A local
resistor of 1000X or less to ground will suffice in
de-Q’ing any resonance A 100 pF or larger capac-
itor can also serve as a bypass
Thermal Considerations
The package of the EL1056 includes two fused
leads on each side which are connected to the in-
ternal die mounting metal Heat generated in the
die flows through the mounting pad to the fused
leads and then to the circuit-board copper
achieving a thermal resistance to air around
40 W Characterization curves show the thermal
resistance versus airflow rate Consult the
EL1056 Demonstration Board literature for a
suggested board pattern Note that thicker layers
of copper than we used improves the thermal re-
sistance further to a limit of 22 C W for an ‘‘infi-
nite heatsink’’ directly soldered to the fused
leads
As a practical limit the die temperature should
be kept to 125 C rather than the allowable 150 C
to retain optimum timing accuracies
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