EL7457C Elantec Semiconductor, EL7457C Datasheet - Page 10

• Manufacturer Part Number: EL7457C
• Description: 40MHz Non-Inverting Quad CMOS Driver
• Manufacturer: Elantec Semiconductor

EL7457C
40MHz Non-Inverting Quad CMOS Driver
Application Information:
Product Description
The EL7457C is a high performance 40MHz ultra-high
speed quad driver. Each channel of the EL7457C con-
sists of a single P-channel high side driver and a single
N-channel low side driver. These 3
the output (OUT
VH and VL respectively, depending on the input logic
signal (IN
of high and low voltage pins.
A common output enable (OE) pin is available on the
EL7457C. This pin, when pulled low will put all outputs
in to the high impedance state.
The EL7457C is available in both the 16-pin SOIC and
the space saving 16-pin QSOP packages. The relevant
package should be chosen depending on the calculated
power dissipation.
Supply Voltage Range and Input Compatibility
The EL7457C is designed for operation on supplies from
5V to 15V with 10% tolerance (i.e. 4.5V to 16.5V). The
table on page 6 shows the specifications for the relation-
ship between the V
EL7457C does not contain a true analog switch and
therefore VL should always be less than VH.
All input pins are compatible with both 3V and 5V
CMOS signals With a positive supply (V
EL7457C is also compatible with TTL inputs.
Power Supply Bypassing
When using the EL7457C, it is very important to use
adequate power supply bypassing. The high switching
currents developed by the EL7457C necessitate the use
of a bypass capacitor on both the positive and negative
supplies. It is recommended that a 4.7µ F tantalum
capacitor be used in parallel with a 0.1µ F low-induc-
tance ceramic MLC capacitor. These should be placed as
close to the supply pins as possible. It is also recom-
mended that the VH and VL pins have some level of
bypassing, especially if the EL7457C is driving highly
capacitive loads.
X
). It should be noted that there is only one set
X
) to either the high or low voltage, on
S
+, V
S
-, VH, VL and GND pins. The
devices will pull
S
+) of 5V, the
10
Power Dissipation Calculation
When switching at high speeds, or driving heavy loads,
the EL7457C drive capability is limited by the rise in die
temperature brought about by internal power dissipation.
For reliable operation die temperature must be kept
below T
power dissipation for a given application prior to select-
ing the package type.
Power dissipation may be calculated:
where:
• V
• V
• C
• C
• I
• f is frequency
Having obtained the application’s power dissipation, a
maximum package thermal coefficient may be deter-
mined, to maintain the internal die temperature below
T
where:
• T
• T
• PD is the power dissipation calculated above.
Using the value of
tion may be selected.
In applications with a
QSOP may be used. A 16-pin SOIC is suitable for appli-
cations with a
jmax
V
S
out
jmax
max
L
INT
S
S
is the quiescent supply current (3mA max.) and
+ to V
.
is the total power supply to the EL7457C (from
is the load capacitance,
is the swing on the output (VH - VL),
is the maximum operating temperature,
is the internal load capacitance (50pF max.),
PD
is the maximum junction temperature (125°C),
jmax
=
S
-),
(125°C). It is necessary to calculate the
V
S
ja
value greater than 110°C/W. However,
I
S
ja
ja,
+
=
a suitable package for the applica-
4
1
ja
--------------------------------------- -
greater than 158°C/W, a 16-pin
T
C
jmax
INT
PD
V
–
2
S
T
max
f
+
C
L
V
O UT
2
f