Datasheet

'M
C
=
40x10
-6
.
R
SL
.
F
S
R
SEN
Amps
second
LM3488
LM3488-Q1
www.ti.com SNVS089M –JULY 2000–REVISED MARCH 2013
Figure 24. Compensation Ramp Avoids Sub-Harmonic Oscillation
The compensation ramp has been added internally in LM3488. The slope of this compensation ramp has been
selected to satisfy most of the applications. The slope of the internal compensation ramp depends on the
frequency. This slope can be calculated using the formula:
M
C
= V
SL
.F
S
Volts/second (3)
In the above equation, V
SL
is the amplitude of the internal compensation ramp. Limits for V
SL
have been specified
in the electrical characteristics.
In order to provide the user additional flexibility, a patented scheme has been implemented inside the IC to
increase the slope of the compensation ramp externally, if the need arises. Adding a single external resistor,
R
SL
(as shown in Figure 25) increases the slope of the compensation ramp, M
C
by :
(4)
In this equation, ΔV
SL
is equal to 40.10
-6
R
SL
. Hence,
(5)
ΔV
SL
versus R
SL
has been plotted in Figure 26 for different frequencies.
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