ALD4704 ALD [Advanced Linear Devices], ALD4704 Datasheet - Page 4

• Manufacturer Part Number: ALD4704
• Description: QUAD RAIL-TO-RAIL CMOS OPERATIONAL AMPLIFIER
• Manufacturer: ALD [Advanced Linear Devices]

Design & Operating Notes:
1. The ALD4704 CMOS operational amplifier uses a 3 gain stage
2. The ALD4704 has complementary p-channel and n-channel input
ALD4704A/ALD4704B
ALD4704
architecture and an improved frequency compensation scheme to
achieve large voltage gain, high output driving capability, and better
frequency stability. The ALD4704 is internally compensated for unity
gain stability using a novel scheme. This design produces a clean
single pole roll off in the gain characteristics while providing for more
than 70 degrees of phase margin at the unity gain frequency. A unity
gain buffer using the ALD4704 will typically drive 400pF of external
load capacitance without stability problems. In the inverting unity gain
configuration, it can drive up to 800pF of load capacitance. Compared
to other CMOS operational amplifiers, the ALD4704 is much more
resistant to parasitic oscillations.
differential stages connected in parallel to accomplish rail to rail input
common mode voltage range. With the common mode input voltage
close to the power supplies, one of the two differential stages is
switched off internally. To maintain compatibility with other opera-
tional amplifiers, this switching point has been selected to be about
1.5V above the negative supply voltage. As offset voltage trimming on
the ALD4704 is made when the input voltage is symmetrical to the
supply voltages, this internal switching does not affect a large variety
of applications such as an inverting amplifier or non-inverting amplifier
with a gain greater than 2.5 (5V operation), where the common mode
voltage does not make excursions below this switching point.
10000
1000
100
1.0
0.1
10
7
6
3
5
4
2
COMMON MODE INPUT VOLTAGE RANGE
-50
2
INPUT BIAS CURRENT AS A FUNCTION
AS A FUNCTION OF SUPPLY VOLTAGE
T
A
-25
= 25 C
OF AMBIENT TEMPERATURE
V
3
S
AMBIENT TEMPERATURE ( C)
= 5.0V
0
SUPPLY VOLTAGE (V)
4
25
50
TYPICAL PERFORMANCE CHARACTERISTICS
5
75
6
100
125
7
Advanced Linear Devices
3. The input bias and offset currents are essentially input protection diode
4. The output stage consists of class AB complementary output drivers,
5. The ALD4704 operational amplifier has been designed with static
reverse bias leakage currents, and are typically less than 1pA at room
temperature. This low input bias current assures that the analog signal
from the source will not be distorted by input bias currents. For
applications where source impedance is very high, it may be neces-
sary to limit noise and hum pickup through proper shielding.
capable of driving a low resistance load. The output voltage swing is
limited by the drain to source on-resistance of the output transistors as
determined by the bias circuitry, and the value of the load resistor
when connected. In the voltage follower configuration, the oscillation
resistant feature, combined with the rail to rail input and output feature,
makes the ALD4704 an effective analog signal buffer for medium to
high source impedance sensors, transducers, and other circuit net-
works.
discharge protection and to minimize latch up. However, care must be
exercised when handling the device to avoid strong static fields. In
using the operational amplifier, the user is advised to power up the
circuit before, or simultaneously with, any input voltages applied and
to limit input voltages to not exceed 0.3V of the power supply voltage
levels. Alternatively, a 100K
terminals will limit input currents to acceptable levels while causing
very small or negligible accuracy effects.
1000
100
10
12
16
14
10
OPEN LOOP VOLTAGE GAIN AS A FUNCTION
1
0
8
6
4
2
OF SUPPLY VOLTAGE AND TEMPERATURE
0
0
INPUTS GROUNDED
OUTPUT UNLOADED
T
SUPPLY CURRENT AS A FUNCTION
A
= -55 C
+125 C
+25 C
+80 C
1
-25 C
OF SUPPLY VOLTAGE
2
SUPPLY VOLTAGE (V)
SUPPLY VOLTAGE (V)
2
3
4
or higher value resistor at the input
4
5
} -55 C
R
R
} +125 C
} +25 C
6
L
L
= 10K
= 5K
6
7
8
4