5

Application Information

Power Supply Decoupling

Although not absolutely necessary, it is recommended that

all power supply lines be decoupled with 0.01

µF ceramic

capacitors to ground. Decoupling capacitors should be

located as near to the amplifier terminals as possible.

Considerations For Prototyping:

The following list of recommendations are suggested for

prototyping.

1. Resolving low level signals requires minimizing leakage

currents caused by external circuitry. Use of quality

insulating materials, thorough cleaning of insulating

surfaces and implementation of moisture barriers when

required is suggested.

2. Error voltages generated by thermocouples formed

between dissimilar metals in the presence of temperature

gradients should be minimized. Isolation of low level

circuity from heat generating components is

recommended.

3. Shielded cable input leads, guard rings and shield drivers

are recommended for the most critical applications.

Large Capacitive Loads

When driving large capacitive loads (>500pF), a small value

resistor (

≈50Ω) should be connected in series with the

output and inside the feedback loop.

Offset Voltage Adjustment (See Figure 3)

A 20k

Ω balance potentiometer is recommended if offset

nulling is required. However, other potentiometer values

such as 10k

Ω, 50kΩ and 100kΩ may be used. The

minimum adjustment range for given values is

to output.

Saturation Recovery

Input and output saturation recovery time is negligible in

most applications. However, care should be exercised to

avoid exceeding the absolute maximum ratings of the

device.

Differential Input Voltages

Inputs are shunted with back-to-back diodes for overvoltage

protection. In applications where differential input voltages in

excess of 1V are applied between the inputs, the use of

limiting resistors at the inputs is recommended.

Typical Applications

The excellent input and gain characteristics of HA-5135 are

well suited for precision integrator applications. Accurate

integration over seven decades of frequency using HA-5135,

virtually nullifies the need for more expensive chopper-type

amplifiers.

and high PSRR make HA-5135 ideally suited for precision

detector applications, such as the zero crossing detector

shown in Figure 5.

2

6

1

7

8

V+

+

4

3

5

20k

Ω

OPTIONAL

CONNECTION

-

FIGURE 3. OFFSET NULLING CONNECTIONS

2

1

7

8

+

4

3

5

C

6

R

OUT

-

FIGURE 4. PRECISION INTEGRATOR

HA-5135