TC2575 datasheet(10/25 Pages) TELCOM

10 / 25 page

TC2575

1.0A Step-Down Switching Regulator

TC2575-1 3/13/00

Procedure (Adjustable Output Version: TC2575-ADJ) (Continued)

Procedure

Example

5. Output Capacitor Selection (COUT )

A. Since the TC2575 is a forward–mode switching regulator

with voltage mode control, its open loop 2–pole–1–zero

frequency characteristic has the dominant pole–pair

determined by the output capacitor and inductor values.

For stable operation, the capacitor must satisfy the

following requirement:

COUT ≥ 7.785

VIN(max)

[

µF]

VOUT x L [µF]

B. Capacitor values between 10

µF and 2000µF will satisfy

the loop requirements for stable operation. To achieve an

acceptable output ripple voltage and transient response,

the output capacitor may need to be several times larger

than the above formula yields.

C. Due to the fact that the higher voltage electrolytic capaci-

tors generally have lower ESR (Equivalent Series

Resistance) numbers, the output capacitor’s voltage

rating should be at least 1.5 times greater than the output

voltage. For a 5.0V regulator, a rating of at least 8.0V is

appropriate, and a 10V or 16V rating is recommended.

5. Output Capacitor Selection (COUT )

COUT ≥ 7.785

= 53

µF

8 x 220

To achieve an acceptable ripple voltage, select

COUT 100µF electrolytic capacitor.

Table 1. Inductor Selection Guide

Inductor Code

Inductor Value

Pulse Eng

Renco

AIE

Tech 39

L100

100

µHPE–92108

RL2444

415–0930

77 308 BV

L150

150

µHPE–53113

RL1954

415–0953

77 358 BV

L220

220

µHPE–52626

RL1953

415–0922

77 408 BV

L330

330

µHPE–52627

RL1952

415–0926

77 458 BV

L470

470

µHPE–53114

RL1951

415–0927

–

L680

680

µHPE–52629

RL1950

415–0928

77 508 BV

H150

150

µH

PE–53115

RL2445

415–0936

77 368 BV

H220

220

µHPE–53116

RL2446

430–0636

77 410 BV

H330

330

µHPE–53117

RL2447

430–0635

77 460 BV

H470

470

µHPE–53118

RL1961

430–0634

–

H680

680

µHPE–53119

RL1960

415–0935

77 510 BV

H1000

1000

µHPE–53120

RL1959

415–0934

77 558 BV

H1500

1500

µHPE–53121

RL1958

415–0933

–

H2200

2200

µHPE–53122

RL2448

415–0945

77 610 BV

Note: *Contact Manufacturer

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