NJM2729 データシートの表示（PDF） - Japan Radio Corporation

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NJM2729

Precision Operational Amplifier

Japan Radio Corporation  

NJM2729

■ Application Information

●Power Supply Bypassing

The NJM2729 is a high precision operational amplifier featuring low offset voltage, high voltage gain, high CMR, high SVR

and so on. To maximize such a high performance with stable operation, the NJM2729 should be operated by clean and low

impedance supply voltage. So, the bypass capacitor should be connected to the NJM2729’s both power supply terminals

(V+ and V-) as shown in Fig.1. The bypass capacitors should be placed as close as possible to IC package

V+

2− 7

NJM2729

6

3+

4

V-

Fig.1 Power Supply Bypassing Circuit

●Thermoelectric Effect

The NJM2729 is a high precision operational amplifier featuring low offset voltage and low offset voltage thermal drift. To

achieve such a high performance, take care about thermoelectric effect possibly occurs on each input terminal of the

NJM2729. Generally, if there are thermal mismatches at the junction of different types of metals, the thermoelectric voltage

(Seebeck effect) occurs at the junction. The thermoelectric voltages possibly occur at the junction of PCB metal patterns

and NJM2729’s each input terminal metal. If there is thermal mismatch in-between NJM2729’s each input terminal metal,

the thermoelectric voltages generated on each input terminal possibly have different voltage each. This voltage difference

causes offset voltage and offset voltage thermal drift of the NJM2729. To minimize this voltage difference, the thermal

mismatch in-between NJM2729’s each input terminal and PCB metal should be minimized.

●Offset Voltage Adjustment

The NJM2729 has offset voltage trim terminals (pin1 and pin8) as shown in below Fig.2. By connecting external

potentiometer in the range of 20Kohm, the offset voltage trim range is ±3mV. This offset voltage trim is effective only for

offset voltage at room temperature, not for offset voltage thermal drift. If offset voltage adjustment is not in use, leave pin1

and pin8 open (un-connected).

Rp=20kΩ V+

1

2

8

−

7

NJM2729

6

3+

4

V-

Fig.2 Offset Voltage Trim Circuit

E1

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