R

F

1kΩ

C

S

1.88nF

NG

1 = 1 + RF/RG = 2

NG

2 = 1 + CS/CF = 10

OPA552

+30V

–30V

V

IN

V

OUT

C

F

208pF

R

G

1kΩ

Time (1µs/div)

OPA552

OPA551, OPA552

SBOS100B – JULY 1999 – REVISED JANUARY 2016

www.ti.com

Typical Application (continued)

Figure 31. Compensation of the OPA552 for G = 1

Figure 32. Small-Signal Step Response for

Figure 31

8.2.2.4 Offset Voltage Error Calculation

The offset voltage (VOS) of the OPA51 and OPA552 is specified with a ±30-V power supply and the common-

mode voltage centered between the supplies (VS / 2 = 0 V). Additional specifications for power-supply rejection

and common-mode rejection are provided to allow the user to easily calculate worst-case excepted offset under

the conditions of a given application.

Power-supply rejection ratio (PSRR) is specified in µV/V. For the OPA55x, worst-case PSRR is 30 µV/V, which

means for each volt of change in total power-supply voltage, the offset may shift by up to 30 µV/V. Common-

mode rejection ratio (CMRR) is specified in dB, which can be converted to µV/V using Equation 1:

CMRR in (V/V) = 10

[(CMRR in dB)/–20]

(1)

For the OPA55x, the worst-case CMRR at ±30-mV supply over the full common-mode range is 96 dB, or

approximately 15.8 µV/V. This result means that for every volt of change in common-mode, the offset may shift

up to 15.8 µV. These numbers can be used to calculate excursions from the specified offset voltage under

different applications conditions. For example, a common application might configure the amplifier with a –48-V

single supply with –6-V common-mode. This configuration represents a 12-V variation in power supply: ±30 V or

60 V in the offset specification versus 48 V in the application. In addition, this configuration has an 18-V variation

in common-mode voltage: VS / 2 = –24 V is the specification for these power supplies, but the common-mode

voltage is –6 V in the application.

Calculation of the worst-case expected offset for this example is calculated by Equation 2 and Equation 3.

Worst-case VOS = maximum specified VOS + (power-supply variation × PSRR) + (common-mode variation × CMRR) (2)

VOSwc = 5 mV + (12 V × 30 µV/V) + (18 V × 15.8 µV/V) = ±5.64 mV

(3)

16

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