Datasheet

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SBOS303C − JUNE 2004 − REVISED AUGUST 2008
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22
INPUT AND ESD PROTECTION
The OPA820 is built using a very high-speed complementary
bipolar process. The internal junction breakdown voltages are
relatively low for these very small geometry devices. These
breakdowns are reflected in the Absolute Maximum Ratings
table. All device pins are protected with internal ESD
protection diodes to the power supplies, as shown in
Figure 13.
External
Pin
+V
CC
−
V
CC
Figure 13. Internal ESD Protection
These diodes provide moderate protection to input overdrive
voltages above the supplies as well. The protection diodes
can typically support 30mA continuous current. Where higher
currents are possible (for example, in systems with ±15V
supply parts driving into the OPA820), current-limiting series
resistors should be added into the two inputs. Keep these
resistor values as low as possible since high values degrade
both noise performance and frequency response. Figure 14
shows an example protection circuit for I/O voltages that may
exceed the supplies.
OPA820
+5V
−
5V
50
Ω
50
Ω
Power−supply
decoupling not shown.
174
Ω
D1 D2
V
1
R
G
301
Ω
50
Ω
R
F
301
Ω
V
O
D1 = D2 IN5911 (or equivalent)
50
Ω
Source
Figure 14. Gain of +2 with Input Protection