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REV A.03 www.3peakic.com.cn
36V Single supply, Precision RRO Op-amps With 7MHz Bandwidth
Pin Functions
-IN: Inverting Input of the Amplifier. Voltage range of this
pin can go from V– to (V+ - 2.0V).
+IN: Non-Inverting Input of Amplifier. This pin has the
same voltage range as –IN.
V+ or +VS: Positive Power Supply. Typically the voltage
is from 2.7V to 36V. Split supplies are possible as long
as the voltage between V+ and V– is between 2.7V and
36V. A bypass capacitor of 0.1μF as close to the part as
possible should be used between power supply pins or
between supply pins and ground.
V– or –VS: Negative Power Supply. It is normally tied to
ground. It can also be tied to a voltage other than
ground as long as the voltage between V+ and V– is from
2.7V to 36V. If it is not connected to ground, bypass it
with a capacitor of 0.1μF as close to the part as
possible.
OUT: Amplifier Output. The voltage range extends to
within milli-volts of each supply rail.
Operation
The TP127X have input signal range from V– to (V+ –
2.0V). The output can extend all the way to the supply
rails. The input stage is comprised of a PMOS
differential amplifier. The Class-AB control buffer and
output bias stage uses a proprietary compensation
technique to take full advantage of the process
technology to drive very high capacitive loads. This is
evident from the transient over shoot measurement
plots in the Typical Performance Characteristics.
Applications Information
EMI Harden
The EMI hardening makes the TP1271/1272/1274 a must for almost all op amp applications. Most applications are
exposed to Radio Frequency (RF) signals such as the signals transmitted by mobile phones or wireless computer
peripherals. The TP1271/1272/1274 will effectively reduce disturbances caused by RF signals to a level that will be
hardly noticeable. This again reduces the need for additional filtering and shielding Using this EMI resistant series of
op amps will thus reduce the number of components and space needed for applications that are affected by EMI, and
will help applications, not yet identified as possible EMI sensitive, to be more robust for EMI.
Wide Supply Voltage
The TP1271/1272/1274 operational amplifiers can operate with power supply voltages from 2.7V to 36V. Each
amplifier draws 0.9mA quiescent current at 36V supply voltage. The TP1271/1272/1274 is optimized for wide
bandwidth low power applications. They have an industry leading high GBW to power ratio and the GBW remains
nearly constant over specified temperature range.
Low Input Bias Current
The TP1271/1272/1274 is a CMOS OPA family and features very low input bias current in 3pA range. The low input
bias current allows the amplifiers to be used in applications with high resistance sources. Care must be taken to
minimize PCB Surface Leakage. See below section on “PCB Surface Leakage” for more details.
PCB Surface Leakage
In applications where low input bias current is critical, Printed Circuit Board (PCB) surface leakage effects need to be
considered. Surface leakage is caused by humidity, dust or other contamination on the board. Under low humidity
conditions, a typical resistance between nearby traces is 1012Ω. A 5V difference would cause 5pA of current to flow,
which is greater than the TP1271/1272/1274 OPA’s input bias current at +27°C (±3pA, typical). It is recommended to
use multi-layer PCB layout and route the OPA’s -IN and +IN signal under the PCB surface.
The effective way to reduce surface leakage is to use a guard ring around sensitive pins (or traces). The guard ring is
biased at the same voltage as the sensitive pin. An example of this type of layout is shown in Figure 2 for Inverting
Gain application.