ꢀ ꢁꢁꢂ ꢃ ꢄ ꢅ ꢆꢇꢈ ꢆꢄ ꢈ ꢆꢂꢈ ꢆꢅ ꢈ ꢆꢉ ꢈꢆ ꢊ ꢆꢋ ꢄ
ꢌ ꢍꢎꢆꢏ ꢍꢎꢐꢑ ꢒꢓ ꢁ ꢔꢍꢕ ꢁꢀ ꢑꢑ ꢐꢖꢗꢆꢔꢍ ꢘ ꢐ ꢏꢎ ꢔ
ꢙ
SGLS245 − MAY 2004
PARAMETER MEASUREMENT INFORMATION
Error Amplifier
Gain/Phase Response
Oscillator
0.2 V
REF
RC
8
4
R
S
Q
R
T
2.5 V
C
T
The UCC2813-0/1/2/3/4/5 oscillator generates
a sawtooth
waveform on RC. The rise time is set by the time constant of RT and
CT. The fall time is set by CT and an internal transistor
on-resistance of approximately 125. During the fall time, the output
is off and the maximum duty cycle is reduced below 50% or 100%
depending on the part number. Larger timing capacitors increase
the discharge time and reduce the maximum duty cycle and
frequency.
Figure 1
Figure 2
UCC2813-0/1/2/4 Oscillator Frequency
UCC2813-3/5 V
vs
REF
vs
R and C
V
T
T
CC
I
= 0.5 mA
LOAD
Figure 3
Figure 4
8
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