Datasheet

LM1577, LM2577
www.ti.com SNOS658D –JUNE 1999–REVISED APRIL 2013
Table 2. Table of Standardized Inductors and
Manufacturer's Part Numbers
(1)
Inductor Manufacturer's Part Number
Code Schott Pulse Renco
L47 67126980 PE - 53112 RL2442
L68 67126990 PE - 92114 RL2443
L100 67127000 PE - 92108 RL2444
L150 67127010 PE - 53113 RL1954
L220 67127020 PE - 52626 RL1953
L330 67127030 PE - 52627 RL1952
L470 67127040 PE - 53114 RL1951
L680 67127050 PE - 52629 RL1950
H150 67127060 PE - 53115 RL2445
H220 67127070 PE - 53116 RL2446
H330 67127080 PE - 53117 RL2447
H470 67127090 PE - 53118 RL1961
H680 67127100 PE - 53119 RL1960
H1000 67127110 PE - 53120 RL1959
H1500 67127120 PE - 53121 RL1958
H2200 67127130 PE - 53122 RL2448
(1) Schott Corp., [phone]
1000 Parkers Lake Rd., Wayzata, MN 55391
Pulse Engineering, [phone]
P.O. Box 12235, San Diego, CA 92112
Renco Electronics Inc., [phone]
60 Jeffryn Blvd. East, Deer Park, NY 11729
2. Compensation Network (R
C
, C
C
) and Output Capacitor (C
OUT
) Selection
R
C
and C
C
form a pole-zero compensation network that stabilizes the regulator. The values of R
C
and C
C
are
mainly dependant on the regulator voltage gain, I
LOAD(max)
, L and C
OUT
. The following procedure calculates values
for R
C
, C
C
, and C
OUT
that ensure regulator stability. Be aware that this procedure doesn't necessarily result in R
C
and C
C
that provide optimum compensation. In order to ensure optimum compensation, one of the standard
procedures for testing loop stability must be used, such as measuring V
OUT
transient response when pulsing
I
LOAD
(see Figure 39).
A. First, calculate the maximum value for R
C
.
(8)
Select a resistor less than or equal to this value, and it should also be no greater than 3 kΩ.
B. Calculate the minimum value for C
OUT
using the following two equations.
(9)
The larger of these two values is the minimum value that ensures stability.
C. Calculate the minimum value of C
C
.
(10)
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