e7804 Semtech Corporation, e7804 Datasheet - Page 25

• Manufacturer Part Number: e7804
• Description: 133 Mhz Quad Pin Electronics Driver And Window Comparator
• Manufacturer: Semtech Corporation

junction to air with 400 linear feet per minute (LFPM) of
airflow is specified at 22°C/W. At operating points greater
than or equal to this value, no additional heatsinking is
needed to keep the die temperatures below the maximum
00°C as long as the ambient temperature of the 400
LFPM air does not exceed 35°C.
More information on heatsink system selections can be
read on heatsink vendors’ web sites and in the Semtech
Application Note #ATE-A2 Cooling High Power, High Density
Pin Electronics.
Protection Considerations
The E7804 has ESD protection on its input and outputs.
The E7804 has internal, high voltage, disconnect switches
for VIO and POUT pins. When open, these provide
protection against voltages input into VIO and POUT which
might have damaged drivers, comparators, and other
internal circuits.
Power Supply Sequencing/Latch-Up Protection
In order to avoid the possibility of latch-up when powering
this part up (or down), be careful that the conditions listed
in the Absolute Maximum Ratings are never violated. That
is, the power supplies should never be reverse-polarity with
respect to ground, and the input signals should never go
beyond the power supply rails.
Furthermore, the lower-voltage analog supplies should never
be greater than the higher-voltage supplies
< VCC < VXX). This can easily be implemented by utilizing
the diode circuit depicted in Figure 4 for each PCB that
has E7804 devices on it. The following conditions must be
met at all times during power-up and power-down.
TEST AND MEASUREMENT PRODUCTS
Application Information (continued)
©
2007 Semtech Corp. / Rev. 7, 02/26/07
.
2.
3.
4.
VEE GND VAA VCC VXX
GND VDD VCC
VEE Analog Inputs VCC or VXX
GND Digital Inputs VDD
(VAA
The following sequencing can be used as a guideline when
powering up:
The recommended power-down sequence is the reverse
order of the power-up sequence.
One approach to ensure that the power supply polarities do
not become reversed is to use Schottky diodes, as shown
in Figure 8. One set of these diodes should be used per
board. The optimum type of Schottky will depend on how
much current the power supplies can source.
25
.
2.
3.
4.
Figure 8. Board Level Supply Diodes
VXX
VCC
VAA
VEE
VEE
VXX
VCC
VAA
5.
6.
7.
Schottky's such as 1N5820
Low forward voltage drop
VDD
Digital Inputs
Analog Inputs
VDD
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E7804