OPA622AP BURR-BROWN [Burr-Brown Corporation], OPA622AP Datasheet - Page 10

• Manufacturer Part Number: OPA622AP
• Description: Wide-Bandwidth OPERATIONAL AMPLIFIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

FIGURE 2. Simplified Circuit Diagram.
INPUT PROTECTION
The need for protection from static damage has long been
recognized for MOSFET devices, but all semiconductor
devices deserve protection from this potentially damaging
source. The OPA622 incorporates on-chip ESD protection
diodes as shown in Figure 1. These diodes eliminate the
need for external protection diodes, which can add capaci-
tance and degrade AC performance.
FIGURE 1. Internal ESD Protection.
As shown, all input pins of the OPA622 are protected from
ESD internally by a pair of back-to-back reverse-biased
diodes to either power supply. These diodes begin to con-
duct when the input voltage exceeds either power supply by
about 0.7V. This situation can occur when the amplifier
loses its power supplies while a signal source is still present.
The diodes can typically withstand a continuous current of
30mA without destruction. To ensure long-term reliability,
however, the diode current should be limited externally to
approximately 10mA whenever possible.
The internal protection diodes are designed to withstand
2.5kV (using the Human Body Model) and will provide
adequate ESD protection for most normal handling proce-
dures. However, static damage can cause subtle changes in
External
I
Q
Pin
2
Adjust
Circuitry
100
Bias
®
OPA622
12
+In 4
R
12
Q
+V
(ext.)
CC
+V
–V
CC
CC
–V
5
CC
ESD Protection diodes internally
connected to all pins.
OTA
13
Internal
Circuitry
+ BUF –
R
OG
8
FB
10
the amplifier input characteristics without necessarily
destroying the device. In precision amplifiers, such changes
may degrade offset and drift noticeably. For this reason,
static protection is strongly recommended when handling the
OPA622.
DISCUSSION
OF PERFORMANCE
The OPA622 provides full-power bandwidth previously
unattainable in monolithic devices. In addition, the amplifier
operates with reduced quiescent. The flexibility of the
OPA622 design provides the speed advantages of a current-
feedback amplifier or the precision advantages of a voltage-
feedback amplifier. The programmable quiescent current
feature also helps to adapt the amplifier to the particular
design requirements.
Figure 2 shows the simplified circuit diagram of the OPA622.
It contains four major sections: the bias circuitry, the OTA,
the output buffer, and the feedback buffer.
BIAS CIRCUITRY
The bias circuitry controls the quiescent current of the signal
processing stages, allows external quiescent current setting
using the resistor R
amplifier’s transconductance, and, with its temperature
characteristics, maintains a constant transconductance over
temperature. The quiescent current controls the small-signal
bandwidth and AC behavior. The OPA622 is specified with
a quiescent current of 5mA with R
mended range is 3mA to 8mA.
– In
3
10
OTA
Q
connected from Pin 2 to –V
4
OB
Q
= 430 . The recom-
11
6
9
+V
–V
V
CC OUT
CC OUT
OUT
CC
, sets the