TL-SCSI285

FIXED-VOLTAGE REGULATORS

FOR SCSI ACTIVE TERMINATION

SLVS065F – NOVEMBER 1991 – REVISED JULY 1999

5

POST OFFICE BOX 655303

COMPENSATION CAPACITOR SELECTION INFORMATION

The TL-SCSI285 is a low-dropout regulator. This means that the capacitance loading is important to the

performance of the regulator because it is a vital part of the control loop. The capacitor value and the equivalent

series resistance (ESR) both affect the control loop and must be defined for the load range and the temperature

range. Figures 2 and 3 can be used to establish the capacitance value and ESR range for best regulator

performance.

0.02

0.015

0.005

0

0

0.5

1

1.5

2

2.5

3

0.025

0.035

1/ESR

3.5

4

4.5

5

0.01

0.03

2.4

2.2

2

1.8

0

0.1

0.2

0.3

2.6

2.8

3

0.4

0.5

0.04

1.2

1

0.8

0.6

1.4

1.6

0.4

0.2

0

ESR OF OUTPUT CAPACITOR

vs

LOAD CURRENT

STABILITY

vs

ESR

IL – Load Current – A

Applied Load

Current

Load

Voltage

∆ IL

∆ VL

Min ESR

Boundary

CL = 22.0 µF

CI = 0.1 µF

TJ = 25°C

10

µF

100

µF

400

µF

1000

µF

Figure 3

Max ESR Boundary

Not Recommended

Potential Instability

200

µF

Region of

Best Stability

Not Recommended

Potential Instability

Recommended Min ESR

22

µF

Figure 2