TL2217-285

FIXED-VOLTAGE REGULATORS

FOR SCSI ACTIVE TERMINATION

SLVS066F – NOVEMBER 1991 – REVISED JULY 1999

4

POST OFFICE BOX 655303

COMPENSATION-CAPACITOR SELECTION INFORMATION

The TL2217-285 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. Figure 3 and

Figure 4 can be used to establish the capacitance value and ESR range for best regulator performance.

Figure 1

2.4

2.2

2

1.8

0

0.1

0.2

0.3

2.6

2.8

3

0.4

0.5

Not Recommended

Potential Instability

1.2

1

0.8

0.6

1.4

1.6

0.4

0.2

0

ESR (OUTPUT CAPACITOR)

vs

LOAD CURRENT

IL – Load Current – A

Applied Load

Current

Load

Voltage

∆ IL

∆ VL

Max ESR Boundary

Min ESR

Boundary

CL = 22 µF

CI = 0.1 µF

TJ = 25°C

Figure 2

0.02

0.015

0.005

0

0

0.5

1

1.5

2

2.5

3

0.025

0.035

3.5

4

4.5

5

0.01

0.03

0.04

STABILITY

vs

ESR

Not Recommended

Potential Instability

Recommended Min ESR

22

µF

100

µF

200

µF

400

µF

1000

µF

Region of

Best Stability

1/ESR

10

µF