ISL24021 Datasheet, PDF (9/12 Pages) Intersil Corporation – 1A Rail-to-Rail Input-Output Operational Amplifier

ISL24021
Applications Information
Product Description
The ISL24021 is a high output current, high voltage,
rail-to-rail voltage feedback amplifier. The ISL24021 is
capable of ±1A peak output short circuit current. The
amplifier exhibits beyond the rail input capability, rail-to-rail
output capability and is unity gain stable. Other features
include fast slew rate and settling time which is important in
many applications, such as TFT-LCD panels.
The ISL24021 is available in a 8 Ld 3mmx3mm TDFN
package featuring a standard operational amplifier pinout and
a lead pitch of 0.65mm. The device utilizes a thermally
enhanced package and has a built-in thermal protection
circuit. It is specified for operation over an ambient
temperature range of -40°C to +85°C.
Operating Voltage, Input and Output Capability
The ISL24021 can operate on a single supply or dual supply
configuration. The ISL24021 operating voltage ranges from
a minimum of 4.5V to a maximum of 19V. This range allows
for a standard 5V (or ±2.5V) supply voltage to dip to -10%, or
a standard 18V (or ±9V) to rise by +5.5% without affecting
performance or reliability.
The input common mode voltage range extends 0.5V
beyond the supply rails. For this range, the ISL24021
amplifier is immune to phase reversal. If the common mode
input voltage exceeds the supply voltage by more than 0.5V,
electrostatic protection diodes in the input stage of the
device begin to conduct. It is suggested to not overdrive the
inputs. Figure 23 shows the input voltage driven beyond the
supply rails and the device output swinging between the
supply rails.
The output swings of the ISL24021 typically extend to within
25mV of positive and negative supply rails with load currents
of ±5mA. Decreasing load currents will extend the output
voltage range even closer to the supply rails. Figure 24
shows the input and output waveforms for the device in a
unity-gain configuration. Operation is from ±5V supply with a
1kΩ load connected to GND. The input is a 10V_P-P sinusoid
and the output voltage is approximately 9.95V_P-P.
Refer to the “Electrical Specifications” tables beginning on
page 2 for specific device parameters. Parameter variations
with operating voltage, loading and/or temperature are
shown in the “Typical Performance Curves” on page 5.
V_S = ±2.5V, T_A = +25°C, A_V = 1, V_IN = 6V_P-P
1V
10µs
1V
FIGURE 23. OPERATION WITH BEYOND-THE-RAILS INPUT
.
V_S = ±5V, T_A = +25°C, A_V = 1, V_IN = 10V_P-P
5V
10µs
5V
FIGURE 24. OPERATION WITH RAIL-TO-RAIL INPUT AND
OUTPUT
Output Current Limit
The ISL24021 is capable of ±1A peak output short circuit
current. The device will limit the current to ±1A. Maximum
reliability is maintained if the output continuous current never
exceeds ±300mA. This limit is set by the characteristics of
the internal metal interconnects. See “Power Dissipation” on
page 10 for detailed information about ensuring device
operation with temperature and load conditions.
Driving Capacitive Loads
As load capacitance increases, the -3dB bandwidth will
decrease and peaking can occur. Depending on the
application, it may be necessary to reduce peaking and to
improve device stability. To improve device stability a
snubber circuit or a series resistor may be added to the
output of the ISL24021.
A snubber is a shunt load consisting of a resistor in series
with a capacitor, see Figure 25. An optimized snubber can
improve the phase margin and the stability of the ISL24021.
The advantage of a snubber circuit is that it does not draw
any DC load current or reduce the gain.
Another method to reduce peaking is to add a series output
resistor (typically between 1Ω to 10Ω; see Figure 26).
Depending on the capacitive loading, a small value resistor
may be the most appropriate choice to minimize any
reduction in gain.
9
FN6637.0
June 3, 2009