EL5462
Pin Descriptions
EL5462
2, 6, 9, 13
PIN NAME
IN-
Inverting input
FUNCTION
EQUIVALENT CIRCUIT
V
S
+
IN+
IN-
V
S
-
Circuit 1
3, 5, 10, 12
11
1, 7, 8, 14
IN+
VS-
OUT
Non-inverting input
Negative supply
Output
(See circuit 1)
V
S
+
OUT
V
S
-
Circuit 2
4
VS+
Positive supply
Applications Information
Product Description
The EL5462 is a low power, current-feedback operational
amplifier that offers a wide -3dB bandwidth of 500MHz and a
low supply current of 1.5mA per amplifier. The EL5462
works with supply voltages ranging from a single 5V to 10V
and they are also capable of swinging to within 1V of either
supply on the output. Because of its current-feedback
topology, the EL5462 does not have the normal gain-
bandwidth product associated with voltage-feedback
operational amplifiers. Instead, its -3dB bandwidth to remain
relatively constant as closed-loop gain is increased. This
combination of high bandwidth and low power, together with
aggressive pricing makes the EL5462 the ideal choice for
many low-power/high-bandwidth applications such as
portable, handheld, or battery-powered equipment.
ground plane construction is used, it should be removed
from the area near the inverting input to minimize any stray
capacitance at that node. Carbon or Metal-Film resistors are
acceptable with the Metal-Film resistors giving slightly less
peaking and bandwidth because of additional series
inductance. Use of sockets, particularly for the SO package,
should be avoided if possible. Sockets add parasitic
inductance and capacitance which will result in additional
peaking and overshoot.
Capacitance at the Inverting Input
Any manufacturer’s high-speed voltage or current-feedback
amplifier can be affected by stray capacitance at the
inverting input. For inverting gains, this parasitic capacitance
has little effect because the inverting input is a virtual
ground, but for non-inverting gains, this capacitance (in
conjunction with the feedback and gain resistors) creates a
pole in the feedback path of the amplifier. This pole, if low
enough in frequency, has the same destabilizing effect as a
zero in the forward open-loop response. The use of large-
value feedback and gain resistors exacerbates the problem
by further lowering the pole frequency (increasing the
possibility of oscillation.)
The EL5462 has been optimized with a 600Ω feedback
resistor. With the high bandwidth of these amplifiers, these
resistor values might cause stability problems when
combined with parasitic capacitance, thus ground plane is
not recommended around the inverting input pin of the
amplifier.
Power Supply Bypassing and Printed Circuit
Board Layout
As with any high frequency device, a good printed circuit
board layout is necessary for optimum performance. Low
impedance ground plane construction is essential. Surface
mount components are recommended, but if leaded
components are used, lead lengths should be as short as
possible. The power supply pins must be well bypassed to
reduce the risk of oscillation. The combination of a 4.7µF
tantalum capacitor in parallel with a 0.01µF capacitor has
been shown to work well when placed at each supply pin.
For good AC performance, parasitic capacitance should be
kept to a minimum, especially at the inverting input. (See the
Capacitance at the Inverting Input section) Even when
6
FN7492.0
February 14, 2005
INTERSIL [ INTERSIL CORPORATION ]
